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  • Evolution
  • Springer  (246)
  • Frontiers Media SA  (2)
  • Taylor & Francis  (2)
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  • Blackwell Publishing Ltd
  • 2020-2024  (5)
  • 2005-2009
  • 1990-1994  (178)
  • 1980-1984  (67)
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Year
  • 101
    Electronic Resource
    Electronic Resource
    Phenotypic plasticity and nutrition in a phytophagous insect: consequences of colonizing a new host (1994)
    Springer
    Oecologia 100 (1994), S. 379-385 
    Details
    ISSN: 1432-1939
    Keywords: Tephritidae ; Phenotypic plasticity ; Phytophagous insects ; Evolution ; Selection regime
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The European rose-hip fruit fly Rhagoletis alternata (Diptera, Tephritidae) infests hips of Rosa species. This fly includes R. rugosa, an Asian species now cultivated all over Europe, in its host range. Differences in size and biomass of hips between the ancestral host R. canina and the new host translate into better growth, shorter larval development of larvae within hips of R. rugosa and larger body size and fertility of flies which developing in the new host. In turn this causes different interactions with other organisms of the food-web centred on the host plant. The importance of nutrition and phenotypic plasticity is twofold: they generate a considerable part of life-history diversity within a species and reinforce differences in the ecological context of the ancestral and new host.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317858
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  • 102
    Electronic Resource
    Electronic Resource
    Neighbour specificity between Lolium perenne and Trifolium repens from a natural pasture (1992)
    Springer
    Oecologia 91 (1992), S. 404-409 
    Details
    ISSN: 1432-1939
    Keywords: Trifolium repens ; Lolium perenne ; Competition ; Coadaptation ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Five genotypes of Trifolium repens and Lolium perenne were collected as neighbouring pairs along a fertility gradient in a natural pasture. After vegetative multiplication, the 25 possible combinations of Lolium genotype x Trifolium genotype were planted in the greenhouse in order to investigate competition between the genotypes. The comparison of the five combinations whose individual components had been neighbours with the combinations of genotypes that had not coexisted before disclosed no difference in total biomass production over 7 months. However, the yield of Trifolium increased when grown with the Lolium genotype which had been its natural neighbour, while the latter showed a decrease in yield. This neighbour specificity existed even when carryover effects from the sampling site had been eliminated (preconditioning period of 18 months) and when native Rhizobium strains were not present (inoculation with a non-native strain). The complex pattern of neighbour specificity with time indicated the importance of environmental conditions for its outcome. These results are a further confirmation of positive effects on the growth of Trifolium repens when grown together with its natural neighbour. They are discussed in the context of coexistence and coevolution
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317630
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  • 103
    Electronic Resource
    Electronic Resource
    Fisheries as a large-scale experiment on life-history evolution: disentangling phenotypic and genetic effects in changes in maturation and reproduction of North Sea plaice, Pleuronectes platessa L. (1993)
    Springer
    Oecologia 96 (1993), S. 391-401 
    Details
    ISSN: 1432-1939
    Keywords: Plaice ; Life-history ; Evolution ; Maturation ; Reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper attempts to interpret the observed changes in reproductive strategy of female North Sea plaice since 1900 in the light of possible genetical selection exerted by the fisheries. Somatic growth of juvenile plaice increased between the 1950s and the 1980s, probably as a response to an increase in food availability. Adult growth rate was constant, except during a period of increased population abundance when somatic growth decreased. Both length (L mat) and age at first sexual maturity decreased since 1990. No firm evidence was obtained for a change in total reproductive investment, although size-specific fecundity was reduced in the period of increased population abundance, suggesting a trade-off between egg numbers and egg size. Analysis of the phenotypic response of maturation to an increase in juvenile growth suggested that only a part of the decrease in L mat could be ascribed to the observed increase in juvenile growth. The unexplained part of the change in L mat corresponded with the predicted change due to genetical selection by the fisheries. This supported the hypothesis that fishing caused a genetical change in L mat, although an unequivocal interpretation is not possible from a descriptive study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317510
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  • 104
    Electronic Resource
    Electronic Resource
    Modelling the nutritional ecology of ungulate herbivores: evolution of body size and competitive interactions (1992)
    Springer
    Oecologia 89 (1992), S. 428-434 
    Details
    ISSN: 1432-1939
    Keywords: Ruminant ; Hindgut fermenter ; Nutritional ecology ; Evolution ; Body size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A simulation model is used to quantify relationships between diet quality, digestive processes and body weight in ungulate herbivores. Retention time of food in the digestive tract is shown by regression to scale with W0.27, and to be longer in ruminants than in hindgut fermenters. Allometric relationships between whole gut mean retention time (MRT, h) and weight (W) were: MRT=9.4 W0.255 (r 2=0.80) for hindgut fermenters and MRT=15.3 W0.251 (r 2=0.76) in ruminants. Longer retention of ingesta by large-bodied ruminants and hindgut fermenters increases digestive efficiency relative to small animals and permits them to survive on lower-quality foods. Compared with ruminants, hindgut fermenters' faster throughput is an advantage which outweighs their lower digestive efficiency, particularly on poor quality foods, provided that food resources are not limiting. This suggests that the predominance of ruminants in the middle range of body weights results from their more efficient use of scarce resources under conditions of resource depletion. Considering only physical limitations on intake, the model shows that the allometric coefficient which scales energy intake to body mass is 0.88 in ruminants and 0.82 in hindgut fermenters. The advantages of large body size are countered by disadvantages where food quantity is limited, and we suggest that the upper limit to ungulate body size is determined by the ability to extract nutrients from feeding niches during the nadir of the seasonal cycle of resource quality and abundance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317422
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  • 105
    Electronic Resource
    Electronic Resource
    Pollen mitosis in the slipper orchid Cypripedium fasciculatum (1994)
    Springer
    Sexual plant reproduction 7 (1994), S. 87-94 
    Details
    ISSN: 1432-2145
    Keywords: Evolution ; Microtubules ; Polarity Pollen ; Mitosis ; Orchids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pollen mitosis in the slipper orchid Cypripedium fasciculatum was studied using correlated methods of immunofluorescence and transmission electron microscopy. Unlike the more highly evolved orchids, the cypripedioid orchids shed pollen as monosulcate monads. Prior to pollen mitosis, the microspore nucleus migrates to a proximal position opposite the aperture, as is typical of monocotyledons. There is no distinct generative pole microtubule system (GPMS) like that recently reported in development of pollen polarity in the vandoid moth orchid Phalaenopsis. Instead, microtubules in early prophase are concentrated around the nucleus and extend into the cytoplasm toward the future generative pole. Once the nucleus has migrated to the continuous surface opposite the aperture, microtubules surround the nucleus evenly and show no tendency to be more concentrated in the generative domain. The mitotic spindle, which develops from the perinuclear microtubules, is asymmetrically placed in the microspore and is cone-shaped. The generative pole is broad and closely appressed to the continuous spore surface, while the vegetative pole is pointed and located in the interior of the microspore. As the chromosomes move poleward, microtubules proliferate in the interzone and a phragmoplast develops. The phragmoplast expands in a hemispherical path beyond the interzone following an array of microtubules that radiates from the generative nucleus. Data from this study indicate that evolution of pollen in orchids includes a shift in location of the generative cell from proximal to distal and the evolution of a GPMS, in addition in the well-known trend toward increased pollen aggregation and loss of exine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230576
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  • 106
    Electronic Resource
    Electronic Resource
    Sequences of two rbcS cDNA clones of Batophora oerstedii: structural and evolutionary considerations (1991)
    Springer
    Current genetics 20 (1991), S. 173-175 
    Details
    ISSN: 1432-0983
    Keywords: Batophora ; Small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (SSU) ; rbcS cDNA sequence ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two cDNA clones for the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (SSU) of Batophora oerstedii were isolated and sequenced. One clone contains the coding information for the complete SSU precursor protein. As in two other species of Dasycladaceae (Acetabularia mediterranea and A. cliftonii), the rbcS cDNA sequences of B. oerstedii display the codons TAA or TAG, which seem to code for glutamine, in the reading frame. The amino acid substitution rate for the SSU protein was calculated to be 0.35–0.41 amino acids per 109 years per site based on the substitutions observed in the SSU amino acid sequences of Acetabularia and Batophora.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00312782
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  • 107
    Electronic Resource
    Electronic Resource
    Sequence analysis of the glyceraldehyde-3-phosphate dehydrogenase genes from the basidiomycetes Schizophyllum commune, Phanerochaete chrysosporium and Agaricus bisporus (1992)
    Springer
    Current genetics 22 (1992), S. 447-454 
    Details
    ISSN: 1432-0983
    Keywords: Glyceraldehyde-3-phosphate dehydrogenase (GPD) ; Basiodiomycete ; Sequence ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract GPD genes encoding glyceraldehyde-3-phosphate dehydrogenase were isolated from the homobasidiomycetes Schizophyllum commune, Phanerochaete chrysosporium and Agaricus bisporus. All three species contain one transcriptionally active GPD gene, but A. bisporus also contains an inactive GPD gene (tandemly linked to the active gene). These genes contain 5–9 introns located at conserved positions, differing (except in one case) from intron positions in ascomycetous GPD genes. The predicted amino-acid sequences of the proteins encoded by the three active GPD genes are highly homologous. A comparison with protein sequences from filamentous ascomycetes shows a clear distinction, whereas the GPD genes from ascomycetous yeasts are quite distinct from both the filamentous ascomycetes and basidiomycetes. Promoter regions of ascomycetous GPD genes do not correspond to those of the GPD genes of basidiomycetes which may (partly) explain poor expression in basidiomycetes of introduced genes driven by an ascomycete GPD promoter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326409
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  • 108
    Electronic Resource
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    Comparative analysis of a recombining-repeat-sequence family in the mitochondrial genomes of wheat (Triticum aestivum L.) and rye (Secale cereale L.) (1993)
    Springer
    Current genetics 23 (1993), S. 255-264 
    Details
    ISSN: 1432-0983
    Keywords: Triticum aestivum ; Secale cerele ; Ribosomal RNA genes ; Mitochondrial DNA ; Recombining-repeats ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mitochondrial genomes of wheat and rye each contain a three-member family of recombining repeat peat sequences (the “18S/5S repeat”) that encode genes for 18S and 5S rRNAs (rrn18 and rrn5) and tRNAfMet (trnfM). Here we present, for wheat and rye, the sequence and boundaries of the “common sequence unit” (CSU) that is shared between all three repeat copies in each species. The wheat CSU is 4,429 base-pairs long and contains (in addition to trnfM, rrn18 and rrn5) a putative promoter, three tRNA-like elements (“t-elements”), and part of a pseudogene (“ψatpA c”) that is homologous to chloroplast atpA, which encodes the α subunit of chloroplast F1 ATPase. The rye CSU is somewhat smaller (2,855 base pairs) but contains much the same genic and other sequence elements as its wheat counterpart, except that two of the three t-elements as well as ψatpA c are found in only one of the three downstream flanks of the 18S/5S repeat, outside the CSU boundaries. In interpreting the seuuence data in terms of the evolutionary history of the 18S/5S-repeat family of wheat and rye, we conclude that (1) the wheat-rye form of the 18S/5S repeat most likely originated between 3 and 14 million years ago, in a lineage that gave rise to wheat and rye but not to barley, oasts, rice or maize; (2) the close linkage (1-bp apart) between trnfM and rrn18 is similarly limited in its taxonomic distribution to the wheat/rye lineage; (3) the trnfM-rrn18 pair arose via a single mutation that inserted a sequence block containing trnfM immediately upstream of rrn18; and (4) the presence of a putative promoter upstream of rrn18 in all wheat and rye repeats is consistent with all three repeat copies being transcriptionally active. We discuss these conclusions in the light of the possible functional significance of recombining-repeats in plant mitochondrial genomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00351504
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  • 109
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    psbD sequences of Bumilleriopsis filiformis (Heterokontophyta, Xanthophyceae) and Porphyridium purpureum (Rhodophyta, Bangiophycidae): evidence for polyphyletic origins of plastids (1993)
    Springer
    Current genetics 24 (1993), S. 437-442 
    Details
    ISSN: 1432-0983
    Keywords: Evolution ; Algae ; Plastid ; Endocytobiosis ; Molecular clock ; psbD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nucleotide sequences of the plastidal psbD genes of Bumilleriopsis filiformis and Porphyridium purpureum (encoding the D2 protein of photosystem II) are reported in this paper. The Bumilleriopsis sequence clusters together with Porphyridium when a most parsimonious protein tree of D2 sequences is constructed. A composite D1/D2 protein-similarity network reveals that neither the three red algal sequences nor the two heterokontophyte sequences (Bumilleriopsis, xanthophytes and Ectocarpus, phaeophytes) group together. Therefore, the Heterokontophyta and Rhodophyta may be heterogeneous groups. Instead, it emerges that the D1/D2 proteins of Porphyridium and Bumilleriopsis clearly form a tight cluster. D1 and D2 proteins apparently do not provide a reliable molecular clock. These results fit into hypotheses proposing a polyphyletic origin for complex plastids, even among the supposedly “natural” group of heterokontophytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00351854
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  • 110
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    Comparative analysis of the mitochondrial genomes of Chlamydomonas eugametos and Chlamydomonas moewusii (1992)
    Springer
    Current genetics 21 (1992), S. 197-202 
    Details
    ISSN: 1432-0983
    Keywords: Chlamydomonas ; Gene mapping ; Mitochondrial genome ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We report the cloning and physical mapping of the mitochondrial genome of Chlamydomonas eugametos together with a comparison of the overall sequence structure of this DNA with the mitochondrial genome of Chlamydomonas moewusii, its closely related and interfertile relative. The C. eugametos mitochondrial DNA (mtDNA) has a 24 kb circular map and is thus 2 kb larger than the 22 kb circular mitochondrial genome of C. moewusii. Restriction mapping and heterologous fragment hybridization experiments indicate that the C. eugametos and C. moewusii mtDNAs are colinear. Nine cross-hybridizing restriction fragments common to the C. eugametos and C. moewusii mtDNAs, and spanning the entirety of these genomes, show length differences between homologous fragments which vary from 0.1 to 2.3 kb. A 600 bp subfragment of C. moewusii mtDNA, within one of these conserved fragments, showed no hybridization with the C. eugametos mtDNA. Of the 73 restriction sites identified in the C. eugametos and C. moewusii mtDNAs, five are specific to C. moewusii, eight are specific to C. eugametos and 30 are common to both species. Hybridization experiments with gene probes derived from protein-coding and ribosomal RNA-coding regions of wheat and Chlamydomonas reinhardtii mtDNAs support the view that the small and large subunit ribosomal RNA-coding regions of the C. eugametos and C. moewusii mtDNAs are interrupted and interspersed with each other and with protein-coding regions, as are the ribosomal RNA-coding regions of C. reinhardtii mtDNA; however, the specific arrangement of these coding elements in the C. eugametos and C. moewusii mtDNAs appears different from that of C. reinhardtii mtDNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336841
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  • 111
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    Structure and expression of a plastid-encoded groEL homologous heat-shock gene in a thermophilic unicellular red alga (1992)
    Springer
    Current genetics 21 (1992), S. 521-525 
    Details
    ISSN: 1432-0983
    Keywords: Chaperonin ; Evolution ; Heat shock ; Plastid ; Red algae ; Rubisco-subunit binding protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A gene homologous to the E. coli groEL locus was identified on the plastid genome of the unicellular red alga Cyanidium caldarium strain 14-1-1 (synonym: Galdieria sulphuraria). The complete nucleotide sequence was determined and compared to bacterial-and nuclear-encoded counterparts of higher plants. At the amino-acid level the C. caldarium gene shows 70% homology to the corresponding gene of the cyanobacterium Synechococcus and 52% homology to nuclear-encoded counterparts of higher plants, respectively. Northern and Western blot experiments were used to investigate the dependence of the transcript-and protein-level on culture temperature and heat shock.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00351663
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  • 112
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    Nucleotide sequence of the clustered genes for apocytochrome b6 and subunit 4 of the cytochrome b/f complex in the spinach plastid chromosome (1984)
    Springer
    Current genetics 8 (1984), S. 543-549 
    Details
    ISSN: 1432-0983
    Keywords: Plastid DNA ; Cytochrome b6 gene ; Amino acid sequence ; Hydropathy ; Thylakoid membrane ; Transcript modification ; Evolution ; Spinach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A 2.4 kilobase-pair segment of the spinach plastid chromosome carrying the genes for apocytochrome b6 and subunit 4 of the thylakoid membrane cytochrome b/f complex has been analysed by DNA sequencing and Northern blot analysis. The nucleotide sequence reveals two uninterrupted open reading frames of 211 and 139 triplets coding for two hydrophobic proteins of 23.7 kd (cytochrome b6) and 15.2 kd (subunit 4). The genes are located on the same strand and are separated from each other by 1018 untranslated base pairs. They map adjacent to the gene for the P680 chlorophyll α apoprotein of the photosystem II reaction center. The three genes appear to be under common transcriptional control and the transcripts post-transcriptionally modified. The deduced amino acid sequences of cytochrome b6 and subunit 4 both exhibit significant homology with published sequences from mitochondrial b cytochromes (42 kd) suggesting that these functionally equivalent polypeptides in photosynthetic and respiratory electron transport chains arose monophyletically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410442
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  • 113
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    Three unexpected cases of refracting superposition eyes in crustaceans (1990)
    Springer
    Journal of comparative physiology 167 (1990), S. 71-78 
    Details
    ISSN: 1432-1351
    Keywords: Compound eye ; Optics ; Crustacea ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Compound eyes of the decapod shrimp Gennadas, the hermit crab Dardanus, and the syncarid crustacean Anaspides are studied histologically and with optical experiments. The results demonstrate that these three crustaceans all have refracting superposition eyes. The conclusion is based on the following observations: 1. There is a wide clear-zone, which allows for a superposition image to be formed. 2. Dark-adapted eyes display a large eye-glow, and the ommatidia are not optically isolated. 3. The crystalline cones have the shape typical for refracting superposition eyes, and they contain the required lens-cylinder gradient of refractive index. Euphausiids and mysids were previously thought to be the only crustaceans with refracting superposition eyes, whereas the species investigated here were assumed to have reflecting superposition eyes (decapod shrimps) or apposition eyes (hermit crabs and syncarids). The present findings increase more than twofold the number of crustacean groups that are known to have developed refracting superposition optics. It also provides insight into the evolutionary mechanisms that may have led to the development of this type of imaging optics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192407
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  • 114
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    Contribution of abdominal commissures in the bilateral coordination of the hindlegs during stridulation in the grasshopper Chorthippus dorsatus (1991)
    Springer
    Journal of comparative physiology 169 (1991), S. 191-200 
    Details
    ISSN: 1432-1351
    Keywords: Insect ; Behaviour ; Pattern generation ; Grasshopper ; Stridulation ; Bilateral coordination ; Abdominal ganglia ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Stridulation of grasshoppers is controlled by hemisegmental pattern generator subunits which probably are restricted to the metathoracic ganglion complex (TG3-complex). The coordination of left and right pattern generator subunits depends on commissures of the TG3-complex (Ronacher 1989). The coordination of the stridulatory movements was studied in Chorthippus dorsatus males with partial mediosagittal incisions in the TG3-complex. Animals bearing anterior incisions in the TG3-complex, by which all commissures of the metathoracic neuromere and the first abdominal neuromere were transected, were still able to produce bilaterally coordinated species-specific stridulatory movements. Commissures of the T3- and A1-neuromere, thus, are not necessary, and the A2-, A3-commissures are sufficient for this coordination (Figs. 3, 4). Animals with partial posterior incisions, extending until A1, had deficits in their stridulation pattern; the coordination between the hindlegs was impaired though not completely lost (Fig. 6). This is discussed in view of the structure of ‘stridulation interneurons’ identified in a related grasshopper species (Omocestus viridulus). These results indicate an unexpected substantial contribution of the abdominal neuromeres A2 and A3 to the control of stridulatory movements. This constitutes an interesting parallel to the flight control system of locusts where interneurons located in the first 3 abdominal neuromeres also appear to contribute to the flight pattern generator (Robertson et al. 1982).
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    URL: http://dx.doi.org/10.1007/BF00215866
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  • 115
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    Evolutionary relationship of some stalked and budding bacteria (genera Caulobacter, “Hyphobacter”, Hyphomonas and Hyphomicrobium) as studied by the new integral taxonomical method (1990)
    Springer
    Archives of microbiology 153 (1990), S. 123-128 
    Details
    ISSN: 1432-072X
    Keywords: Oligotrophic bacteria ; Caulobacter ; “Hyphobacter” ; Hyphomonas ; Hyphomicrobium ; Antibiotic sensitivity ; Evolution ; Fatty acids ; Lipids ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new approach was developed for the determination of taxonomic and evolutional relationships among four genera of oligotrophic bacteria. The main idea of this approach is the algorithmized integrative analysis of the morphological and physiological specificity of these bacteria, their 5S rRNA sequences, fatty acid and lipid composition of their membranes, as well as their sensitivity to a large variety of antibiotics. It was shown that the genera Caulobacter and Hyphomonas are closely related to each other, but they are both distant from Hyphomicrobium species. The new genus, “Hyphobacter”, is placed between Caulobacter and Hyphomonas. Taxonomic heterogeneity was found to exist within the genera Caulobacter and Hyphomicrobium. Evolutional pathways from Caulobacter to Hyphomicrobium are proposed on the basis of the present data. No correlations were found between the cell morphology of the organisms and their geno-and chemotaxonomy.
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    URL: http://dx.doi.org/10.1007/BF00247808
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  • 116
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    Sequence divergence of the murB and rrfB genes from Escherichia coli and Salmonella typhimurium (1994)
    Springer
    Archives of microbiology 161 (1994), S. 501-507 
    Details
    ISSN: 1432-072X
    Keywords: Escherichia coli ; Salmonella typhimurium ; murB ; rrfB ; Repetitive extragenic palindrome ; Evolution ; Mutation rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The murB gene of Salmonella typhimurium was cloned and found to be 75% and 82% identical to the DNA and protein sequences, respectively, of the same gene in Escherichia coli. These identities are among the lowest recorded between the two bacteria. Nevertheless, wild-type S. typhimurium murB complemented the known temperature-sensitive E. coli mutant, and wild-type E. coli murB complemented three temperature-sensitive mutants of S. typhimurium. The 5S rRNA gene, rrfB, and the region between murB and rrfB were also cloned and sequenced. The rrfB gene of S. typhimurium differs from rrfB of E. coli in only 2 of 120 nt, but the region between murB and rrfB has diverged greatly and includes a sequence that elosely resembles a repetitive extragenic palindrome of the type normally associated with E. coli. Previous comparisons of gene divergence have suggested that the chromosomal mutation rate is lower in the vicinity of the origin of replication. However, the S. typhimurium murB gene, located 6 map minutes from the origin of replication, is highly substituted at synonymous sites and the sequence between murB and rrfB is significantly modified as well. Thus, murB is an exception to the general observation that genes near the origin of replication show less divergence than do genes elsewhere in the bacterial chromosome.
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    URL: http://dx.doi.org/10.1007/BF00307771
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  • 117
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    Glycogen in thermoacidophilic archaebacteria of the genera Sulfolobus, Thermoproteus, Desulfurococcus and Thermococcus (1982)
    Springer
    Archives of microbiology 132 (1982), S. 297-303 
    Details
    ISSN: 1432-072X
    Keywords: Glycogen ; Archaebacteria ; Thermoacidophiles ; Sulfolobus ; Thermoproteales ; Glucosyl transferase ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glycogen has been found in thermoacidophilic archaebacteria of the genera Sulfolobus, Thermoproteus, Desulfurococcus and Thermococcus. Thermoplasma acidophilum yielded a related, though less defined compound. Glycogen was identified by elementary analysis, infrared spectroscopy, the nature of the hydrolysis products, the iodine reaction, and the nature of the products of periodate oxydation and reduction. The average chain length was 7. From crude extracts of Sulfolobus and Thermoproteus complexes of glycogen with 4 respectively 2 proteins have been isolated by CsCl density gradient centrifugation. In either case, one of the proteins was identified as glucosyl transferase. The glucosyl transferase of Sulfolobus acidocaldarius strain B 12 utilizes UDP-glucose as well as ADP-glucose as substrates, with K m values of 0.42 and 0.2 mM respectively and turnover numbers of 4.6 and 5.2 per second respectively. In electron micrographs the isolated glycogen protein complex appears as scale like aggregates, whereas in cell sections amorphous bodies fill large portions of the cells.
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    URL: http://dx.doi.org/10.1007/BF00413378
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  • 118
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    Evolutionary relationships of superoxide dismutases and glutamine synthetases from marine species of Alteromonas, Oceanospirillum, Pseudomonas and Deleya (1984)
    Springer
    Archives of microbiology 138 (1984), S. 170-178 
    Details
    ISSN: 1432-072X
    Keywords: Superoxide dismutase ; Glutamine synthetase ; Evolution ; Marine bacteria ; Alcaligenes ; Alteromonas ; Deleya ; Oceanospirillum ; Pseudomonas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Evolutionary relationships among marine species assigned to the genera Alteromonas, Oceanospirillum, Pseudomonas, and Alcaligenes were determined by an immunological study of their Fe-containing superoxide dismutases (FeSOD) and glutamine synthetases (GS), two enzymes with differentially conserved amino acid sequences which are useful for determining intermediate and distant relationships, respectively. Five reference antisera were prepared against the FeSODs from Alteromonas macleodii, A. haloplanktis, Oceanospirillum commune, Pseudomonas stanieri, and Deleya pacifica. For GS, a previously prepared antiserum to the enzyme from Escherichia coli was employed. Amino acid sequence similarities for both enzymes were determined by the quantitative microcomplement fixation technique and the Ouchterlony double diffusion procedure. Six evolutionary groups were detected by FeSOD sequence similarities: three subgroups within the genus Alteromonas, the genera Oceanospirillum and Pseudomonas, and a new genus, Deleya (to accommodate marine Alcaligenes). Only four groupings were delineated by the GS data: the latter three genera and one group composed of all the species of Alteromonas. Evidence that all of these subgroups are derived from the evolutionary lineage defined by the purple sulfur photosynthetic bacteria is presented.
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    URL: http://dx.doi.org/10.1007/BF00413018
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    Evolutionary relationships in Vibrio and Photobacterium as determined by immunological studies of superoxide dismutase (1981)
    Springer
    Archives of microbiology 130 (1981), S. 111-120 
    Details
    ISSN: 1432-072X
    Keywords: Evolution ; Vibrio ; Photobacterium ; Alteromonas ; Aeromonas ; Marine bacteria ; Superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The amino acid sequence divergence of superoxide dismutases (SODs) from 22 species and five groups of Vibrio, Photobacterium, and a number of related organisms was determined by means of the microcomplement fixation technique and the Ouchterlony double diffusion procedure. Five reference antisera were used which had been prepared against the purified SODs from V. alginolyticus, V. splendidus II, V. fischeri, V. cholerae, and P. leiognathi. With a few exceptions the results were in agreement with past studies of other informational molecules and provided a comprehensive overview of evolutionary relationships in Vibrio and Photobacterium. The genus Vibrio was found to consist of a major group of primarily marine species which included V. fischeri, V. logei, V. splendidus, V. pelagius, V. nereis, V. campbellii, V. harveyi, V. natriegens, V. alginolyticus, V. parahaemolyticus, V. proteolyticus, V. fluvialis, V. vulnificus, V. nigripulchritudo, and V. anguillarum. On the outskirts of this large and relatively heterogeneous group were the fresh water and estuarine species V. cholerae and V. metschnikovii as well as the marine species V. gazogenes. A considerable distance from Vibrio were the related species of Photobacterium: P. phosphoreum, P. leiognathi, and P. angustum. Both genera were distant from species of Aeromonas as well as from Plesiomonas shigelloides, Escherichia coli, and Alteromonas hanedai, a luminous strict aerobe. The agreement between these and previous studies of evolution of informational molecules in Vibrio and Photobacterium is best explained by vertical evolution (involving no genetic exchange between species) rather than by its opposite — horizontal evolution.
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    URL: http://dx.doi.org/10.1007/BF00411061
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    Fervidobacterium islandicum sp. nov., a new extremely thermophilic eubacterium belonging to the “Thermotogales” (1990)
    Springer
    Archives of microbiology 154 (1990), S. 105-111 
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    ISSN: 1432-072X
    Keywords: Eubacterium ; Thermophile ; Evolution ; Fervidobacterium ; Lipids ; Thermotoga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An extremely thermophilic anaerobic fermentative eubacterium growing at temperatures between 50 and 80°C (opt.: 65°C) was isolated from an Icelandic hot spring. The cells were Gram-negative motile rods, about 1.8 μm in length, and 0.6 μm in width occurring singly and in pairs. About 50% of the cells formed large spheroids at one end similar to Fervidobacterium nodosum. The new isolate H 21 differed from Fervidobacterium nodosum by a 6 mol % higher GC-content of its DNA (41 mol %), its ability to grow on cellulose, and insignificant DNA homology. The lipids of isolate H 21 were similar to that of members of “Thermotogales”. 16S rRNA sequencing of isolate H 21 and Fervidobacterium nodosum indicated (a) that isolate H 21 represents a new species of the genus Fervidobacterium which we name Fervidobacterium islandicum and (b) that the genus Fervidobacterium belongs to the “Thermotogales” branch.
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    URL: http://dx.doi.org/10.1007/BF00423318
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    Primary structure of hemoglobin from cobraNaja naja naja (1994)
    Springer
    The protein journal 13 (1994), S. 669-679 
    Details
    ISSN: 1573-4943
    Keywords: Evolution ; hemoglobin ; primary structure ; snake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cobra snakeNaja naja naja hemoglobin shows four bands on Triton electrophoresis. We present the primary structure of oneα and oneβ chain. The separation of polypeptide chains was achieved by ion exchange chromatography on carboxymethyl cellulose column. The amino acid sequence was established by automatic Edman degradation of the native chains and tryptic and hydrolytic peptides in a gas-phase sequencer. The structural data are compared with those of human and other reptile hemoglobins and reveal not only large variations from human but within reptiles. The amino acid exchanges involve several subunit contacts and heme binding sites. This is the first study on the hemoglobin of a land snake. There are only two amino acid sequences of sea snake hemoglobin (Microcephalophis gracilis gracilis andLiophis miliaris) reported in the literature.
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    URL: http://dx.doi.org/10.1007/BF01886951
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    Technological change and institutional inertia: a game-theoretic approach (1993)
    Springer
    Journal of evolutionary economics 3 (1993), S. 199-224 
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    ISSN: 1432-1386
    Keywords: Technological change ; Institutions ; Evolution ; Games ; C71 ; 017 ; 031
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract In this paper, we study a co-evolutionary model of economic change at two hierarchical levels. At the lower level, “institutions” are given and the focus is on how resources are allocated and innovation produced in response to the pay-off structure induced by prevailing institutions. At the higher level, it is the institutions themselves that change as the outcome of a process of social bargaining. The main objective of the paper is to study the interaction between these two levels of change, attempting to provide some insight on issues like technological/institutional divergence, technological dead-end, institutional inertia, etc.
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    URL: http://dx.doi.org/10.1007/BF01200868
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    Polymorphism with selection and genotype-dependent migration (1981)
    Springer
    Journal of mathematical biology 11 (1981), S. 245-267 
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    ISSN: 1432-1416
    Keywords: Population genetics ; Evolution ; Migration ; Geographical variation ; Habitat choice ; Polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract For a single autosomal locus with multiple alleles both an island and a multiple-niche model with discrete nonoverlapping generations are formulated for the maintenance of genetic variability. Both models incorporate viability selection in an arbitrary way and allow for genotypic differences in the pertinent migration structure. Random drift is ignored, and mating is at random. A global analysis is given for the island model in the neutral case. For a subdivided population, conditions are derived for the existence of a protected polymorphism, and the model is examined in some special two-niche cases. Of particular consideration is the loss of neutral alleles due solely to population regulation and genotype-dependent migration, and the possible existence of equilibrium clines without selection.
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    URL: http://dx.doi.org/10.1007/BF00276896
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    A mathematical model of biological evolution (1982)
    Springer
    Journal of mathematical biology 14 (1982), S. 327-353 
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    ISSN: 1432-1416
    Keywords: Evolution ; Molecular evolution ; Dynamical system ; Neo-Darwinian evolution ; Non-Darwinian evolution ; Neutral theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract In order to understand generally how the biological evolution rate depends on relevant parameters such as mutation rate, intensity of selection pressure and its persistence time, the following mathematical model is proposed: dN n (t)/dt=(m n (t-μ)N n (t)+μN n-1(t) (n=0,1,2,3...), where N n (t) and m n (t) are respectively the number and Malthusian parameter of replicons with step number n in a population at time t and μ is the mutation rate, assumed to be a positive constant. The step number of each replicon is defined as either equal to or larger by one than that of its parent, the latter case occurring when and only when mutation has taken place. The average evolution rate defined by $$\upsilon _\infty \equiv {\text{ lim}}_{t \to \infty } \sum _{n = 0}^\infty nN_n (t)/t\sum _{n = 0}^\infty N_n (t)$$ is rigorously obtained for the case (i) m n (t)=m n is independent of t (constant fitness model), where m n is essentially periodic with respect to n, and for the case (ii) $$m_n (t) = {\text{ }}s( - 1)^{n + [1/\tau ]} $$ (periodic fitness model), together with the long time average m ∞ of the average Malthusian parameter $$\bar m \equiv \sum _{n = 0}^\infty m_n (t)N_n (t)/\sum _{n = 0}^\infty N_n (t)$$ . The biological meaning of the results is discussed, comparing them with the features of actual molecular evolution and with some results of computer simulation of the model for finite populations.
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    URL: http://dx.doi.org/10.1007/BF00275397
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    Evolutionary stable strategies and game dynamics for n-person games (1984)
    Springer
    Journal of mathematical biology 19 (1984), S. 329-334 
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    ISSN: 1432-1416
    Keywords: Evolution ; ESS ; games ; game dynamics ; n-person games ; strategies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract This note contains a generalization of the definition of an evolutionary stable strategy and of the corresponding game dynamics from 2-person to n-person games. This broader framework also allows modelling of several interacting populations or of populations containing different “types” of individuals, for example males and females.
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    URL: http://dx.doi.org/10.1007/BF00277103
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    A model of evolutionary appearance of dissipative structure in ecosystems (1983)
    Springer
    Journal of mathematical biology 18 (1983), S. 13-23 
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    ISSN: 1432-1416
    Keywords: Ecosystem ; Evolution ; Autonomous oscillations ; issipative structure ; Bifurcation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract The interrelation between autonomous oscillations in local systems and stable dissipative structures in spatially distributed systems is analyzed. Darwinian evolution in populations comprising the ecosystem is shown to be able to cause the qualitative rearrangements of dynamic modes and smooth appearance of oscillations in local systems. The same evolutionary mechanisms analyzed within bilocal systems, may lead to appearance of dissipative structures (both smooth and sharp).
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    On the eigenvalue distribution of genetic and phenotypic dispersion matrices: Evidence for a nonrandom organization of quantitative character variation (1984)
    Springer
    Journal of mathematical biology 21 (1984), S. 77-95 
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    ISSN: 1432-1416
    Keywords: Evolution ; quantitative inheritance ; random matrix theory ; morphological integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A quantitative genetic model of “random pleiotropy” is introduced as reference model for detecting the kind and degree of organization in quantitative genetic variation. In this model the genetic dispersion matrix takes the form of G = BB T, where B is a general, real, Gaussian random matrix. The eigenvalue density of the corresponding ensemble of random matrices (ℰG) is considered. The first two moments are derived for variance-covariance matrices G as well as for correlation matrices R, and an approximate expression of the density function is given. The eigenvalue distribution of all empirical correlation matrices deviates from that of a random pleiotropy model by a very large leading eigenvalue associated with a “size factor”. However the frequency-distribution of the remaining eigenvalues shows only minor deviations in mammalian skeletal data. A prevalence of intermediate eigenvalues in insect data may be caused by the inclusion of many functionally unrelated characters. Hence two kinds of deviations from random organization have been found: a “mammal like” and an “insect like” organization. It is concluded that functionally related characters are on the average more tightly correlated than by chance (= “mammal like” organization), while functionally unrelated characters appear to be less correlated than by random pleiotropy (“insect like” organization).
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    Evolutionary optimization and neural network models of behavior (1990)
    Springer
    Journal of mathematical biology 28 (1990), S. 237-256 
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    ISSN: 1432-1416
    Keywords: Behavior ; Evolution ; Neural network ; Dynamic optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract One of the main challenges to the adaptionist program in general and the use of optimization models in behavioral and evolutionary ecology, in particular, is that organisms are so constrained' by ontogeny and phylogeny that they may not be able to attain optimal solutions, however those are defined. This paper responds to the challenge through the comparison of optimality and neural network models for the behavior of an individual polychaete worm. The evolutionary optimization model is used to compute behaviors (movement in and out of a tube) that maximize a measure of Darwinian fitness based on individual survival and reproduction. The neural network involves motor, sensory, energetic reserve and clock neuronal groups. Ontogeny of the neural network is the change of connections of a single individual in response to its experiences in the environment. Evolution of the neural network is the natural selection of initial values of connections between groups and learning rules for changing connections. Taken together, these can be viewed as “design parameters”. The best neural networks have fitnesses between 85% and 99% of the fitness of the evolutionary optimization model. More complicated models for polychaete worms are discussed. Formulation of a neural network model for host acceptance decisions by tephritid fruit flies leads to predictions about the neurobiology of the flies. The general conclusion is that neural networks appear to be sufficiently rich and plastic that even weak evolution of design parameters may be sufficient for organisms to achieve behaviors that give fitnesses close to the evolutionary optimal fitness, particularly if the behaviors are relatively simple.
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    URL: http://dx.doi.org/10.1007/BF00178775
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    Higher selection processes in evolutionary economic change (1992)
    Springer
    Journal of evolutionary economics 2 (1992), S. 1-16 
    Details
    ISSN: 1432-1386
    Keywords: Evolution ; Innovation ; Selection ; Technology ; JEL classification numbers: 036, 112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract Virtually all models of economic change are based on a Darwinian picture of a world where change is gradual, smooth, and where economic survival depends on being more efficient. This paper, drawing from current controversies in evolutionary biology, presents a broader interpretation of evolutionary change in which competitive selection is only one possible reason for economic survival. Economic change is presented as a hierarchical process. At one level, change takes place through the accumulation of small changes based on competitive selection at the margin, as described by standard economic theory. At higher levels, survival depends on processes over which the agent being selected has no control.
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    Firm selection and industry evolution: the post-entry performance of new firms (1994)
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    Journal of evolutionary economics 4 (1994), S. 243-260 
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    ISSN: 1432-1386
    Keywords: Innovation ; Evolution ; Survival and growth ; O ; O3
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract A dynamic framework based on the process of firm selection and industry evolution is used to analyse the post-entry performance of new firms. In particular, it is hypothesized that, based on the stylized fact that virtually all new firms start at a very small scale of output, firm growth and survival are shaped by the need to attain an efficient level of output. The post-entry performance of more than 11,000 U.S. manufacturing firms established in 1976 is tracked throughout the subsequent tenyear period. Firm growth is found to be negatively influenced by firm size but positively related to the extent of scale economies, capital intensity, innovative activity, and market growth. By contrast, the likelihood of survival is identified as being positively influenced by firm size, market growth, and capital intensity, but negatively affected by the degree of scale economies in the industry. When viewed through the dynamic framework of firm selection and industry evolution, the empirical results shed considerable light on several paradoxes in the industrial organization literature, such as the continued persistence over time of an asymmetrical firm-size distribution consisting predominantely of suboptimal scale firms, and the failure of capital intensity and scale economies to substantially deter the entry and start-up of new firms.
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    A branching-process model for the evolution of transposable elements incorporating selection (1991)
    Springer
    Journal of mathematical biology 29 (1991), S. 743-761 
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    ISSN: 1432-1416
    Keywords: Transposable element ; Branching-processes ; Population genetics ; Evolution ; Mobile genetic elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We have formulated a very general mathematical model to analyze the evolution of transposable genetic elements in prokaryotic populations. Transposable genetic elements are DNA sequences able to replicate and insert copies of themselves at new locations in the genome. This work characterizes the equilibrium distribution of copy number under the influence of copy number-dependent selection, transposition and deletion. Our principal results concern the equilibrium distribution of copy number in response to various selective regimes. For particular transposition patterns (e.g. unregulated transposition or copy number-dependent transposition), equilibrium distributions are calculated numerically for a variety of specific selection patterns. Selection is quantified through specification of the expected number of offspring for individuals of each type, which is generally a non-increasing function of copy number, in accord with the usual evolutionary speculations.
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    Discrimination of the sign of frequency differences bySternopygus, an electric fish without a jamming avoidance response (1991)
    Springer
    Journal of comparative physiology 168 (1991), S. 461-467 
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    ISSN: 1432-1351
    Keywords: Electric fish ; Sternopygus ; Jamming avoidance ; Electrolocation conditioning ; Preadaptation ; Temporal filtering ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Several species of weakly electric fish reflexively change their frequency of electric organ discharge (EOD) in response to sensing signals of similar frequency from conspecifics; that is, they exhibit jamming avoidance responses (JAR).Eigenmannia increases its EOD frequency if jammed by a signal of lower frequency and decreases its EOD frequency if jammed by a signal of higher frequency. This discrimination is based on an analysis of the patterns of amplitude modulations and phase differences resulting from signal interference. Fish of the closely related genus,Sternopygus, however, do not exhibit a JAR. Here we show that despite lacking this behavior,Sternopygus shares many sensory processing capacities withEigenmannia: 1. Fish could be conditioned to discriminate the sign of the frequency difference (Df) between an exogenous sinusoidal signal and its own EODs with as few as 300 training trials. 2. Fish can discriminate the sign of Df for jamming signals with an amplitude as low as 2 μV/cm (p-p); which is approximately 40 dB below the amplitude of the fish's EOD, as measured lateral to the operculum. 3. Fish appear to discriminate the sign of Df by evaluating modulations in signal amplitude and differences in the timing of signals received by different areas of the body surface. 4. Sternopygus processes electrosensory information through band-pass modulation filters. Tuning to modulation rates over at least 4–16 Hz exists.
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    Changes in DNA composition in the evolution of Vicia species (1984)
    Springer
    Theoretical and applied genetics 68 (1984), S. 187-192 
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    ISSN: 1432-2242
    Keywords: Vicia ; nuclear DNA ; Evolution ; Base sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The composition of nuclear DNA in 3 Vicia species are compared. The species V. eriocarpa, V. johannis and V. melanops are from three separate subgeneric sections of Vicia and show a fourfold variation in their amounts of nuclear DNA. DNA melting experiments, buoyant density gradient analysis and Cot reassociation experiments show that the quantitiative change in nuclear DNA between the three species is achieved by changes in the amounts of both repetitive and nonrepetitive DNA sequences. It is suggested that while the increase in the repetitive fraction is achieved by the proliferation of repetitive base sequences the increase in the nonrepetitive fraction is due to the steady accretion of highly diverged base sequences resulting from mutations, deletions, insertions and base sequence rearrangements among families of repetitive sequences.
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    Chromosome structure of durum wheat (1990)
    Springer
    Theoretical and applied genetics 79 (1990), S. 397-400 
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    ISSN: 1432-2242
    Keywords: Durum wheat ; C-banding ; Homoeologous pairing ; Chromosome structure ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Meiotic pairing was analyzed at metaphase I in ABRR triticale × rye hybrids to identify the arm homoeology of chromosomes ofTriticum turgidum. Wheat chromosomes were identified using a C-banding technique. Results confirmed that the homoeologous relationships between chromosome arms of the A and B genomes inT. turgidum are the same as inT. aestivum, and that a double translocation involving4AL,5AL, and7BS is present inT. turgidum. It is proposed that a pericentric inversion involving a substantial portion of chromosome4A is present inT. turgidum andT. aestivum.
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    Allozyme variation among the spontaneous species of Sorghum section Sorghum (Poaceae) (1990)
    Springer
    Theoretical and applied genetics 80 (1990), S. 296-304 
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    ISSN: 1432-2242
    Keywords: Sorghum ; Isozyme ; Genetic diversity ; Evolution ; Systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A survey of allozyme variation among the spontaneous taxa of Sorghum section Sorghum was undertaken. Eight plants each of 90 accessions representing the diploid S. bicolor (ssp. arundinaceum and drummondii) and the tetraploids S. almum and S. halepense were analyzed for 17 enzyme systems encoded by 30 loci. Low levels of variation were found within and among accessions, although there was more variation than is typical of inbreeding species. We found an average of 3.2 alleles per locus in ssp. arundinaceum, with a mean expected heterozygosity for the accessions of 0.034 and total panmictic heterozygosity of 0.154. An analysis of the apportionment of genetic variation among accessions of ssp. arundinaceum indicated that 26% of the variation occurs within accessions and 74% among accessions. Cultivated sorghum contains far less allozymic variation than ssp. arundinaceum, its presumed progenitor. This is consistent with the prediction that cultivated sorghum experienced a loss of genetic variation during domestication. For the most part, cultivated sorghum contains a subset of the allozymes found in ssp. arundinaceum. Principal component analysis revealed continuous variation among the accessions and geographic regions, with accessions failing to segregate into discrete clusters. However, accessions of race virgatum of ssp. arundinaceum occupied one end of the continuum and were, in that sense, distinguished from the other accessions. Similarly, most accessions of S. halepense and S. almum occupied the central portion of the continuum. The allozymic data presented here are consistent with the hypothesized origin of S. halepense via autopolyploidy or segmental allopolyploidy.
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    Genome specificity of rDNA spacer fragments from Oryza sativa L. (1992)
    Springer
    Theoretical and applied genetics 83 (1992), S. 864-870 
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    ISSN: 1432-2242
    Keywords: Wild rice ; rDNA spacer ; Genome-specific DNA sequence ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The intergenic spacer derived from a cloned rDNA unit from a cultivated rice was dissected into several subclones, which were used as probes to analyze sequence homologies between rDNA spacers from wild rice belonging to genome types AA, BB, CC, EE, FF, BBCC, and CCDD. This analysis allowed us to detect several regions with different degrees of homology. A series of 250–260 bp repeats is located in the central part of the AA spacer. This sequence cross-hybridizes with the BB, CC, BBCC, and FF genomes, but is absent in the EE and CCDD genomes. Regions proximal to 25S and 18S sequences are well conserved in all genomes. Finally, two adjacent sequences of 61 bp and 94 bp, located downstream from the repeats, have been found to have a narrow genomic specificity, restricted respectively to AA and FF genomes for the first one and to AA for the second. These data provide new information on the evolution of the ribosomal RNA gene spacer within a complex of related species, and add to our knowledge on the relationship between the various rice genomes.
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    Reconstruction of the phylogeny of the genus Triticum from variation in repeated nucleotide sequences (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 419-429 
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    ISSN: 1432-2242
    Keywords: Genome size ; Geographic distribution ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The potential of variation in repeated nucleotide sequences as a tool for phylogenetic studies was examined by investigating the phylogeny of 13 diploid species of the genus Triticum L. sensu Bowden. Low intraspecific variation in repeated nucleotide sequence families in Triticum indicated that restriction fragment profiles of repeated nucleotide sequences in Southern blots are reliable and uniform characteristics of each species. Cloned repeated nucleotide sequences were hybridized with Southern blots of DNAs of the Triticum species and the outgroup, Lophopyrum elongatum (Host) Á. Löve. The presence or absence of bands in the Southern blot autoradiograms was considered to be a character for phylogenetic analysis. A most parsimonious tree was resolved with the PAUP version 3.0L computer package. The tree was consistent with cytotaxonomic and evolutionary data available on the species.
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    URL: http://dx.doi.org/10.1007/BF00229502
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    Ribosomal DNA polymorphisms and the Oriental-Occidental genetic differentiation in cultivated barley (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 682-687 
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    ISSN: 1432-2242
    Keywords: rDNA polymorphism ; Hordeum vulgaressp. vulgare ; Geographical differentiation ; Evolution ; Phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A total of 289 accessions of cultivated barley were assayed for ribosomal DNA (rDNA) polymorphisms. These accessions comprised four independent samples: (1) 79 entries from China, (2) 59 accessions from Ethiopia, (3) 59 entries from Tibet and (4) 92 entries representing 36 barley growing countries of the world (referred to as “world sample”). In all, 17 rDNA phenotypes (genotypes) were observed, which were composed 10 alleles at two rDNA loci, Rrn1 and Rrn2. The world sample contained the largest number of phenotypes and alleles and also demonstrated the highest level of diversity. Ribosomal DNA phenotypes 104, 112 and 107, 112 occurred at high frequencies worldwide. Allele 112 was the predominant allele of Rrn1 in all four samples, and 104 and 107 were the two major alleles of Rrn2 worldwide. The distributions of rDNA genotypes and alleles demonstrated a clear differentiation of two distinct barley groups: an Oriental group represented by the samples from China and Tibet, which is characterized by allele 107 at the Rrn2 locus (rDNA phenotype 107, 112); and an Occidental group, represented by Ethiopian and world samples, which is comprised mostly of allele 104 at the Rrn2 locus (rDNA phenotype 104, 112). The results also raised new questions concerning the phylogeny and evolution of cultivated barley.
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    URL: http://dx.doi.org/10.1007/BF00224168
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    Chloroplast DNA diversity among wild and cultivated members of Cucurbita (Cucurbitaceae) (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 859-865 
    Details
    ISSN: 1432-2242
    Keywords: Cucurbita ; Phylogeny ; cpDNA ; Domestication ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cladistic analysis of 86 chloroplast DNA restriction-site mutations among 30 samples representing 15 species of Cucurbita indicates that annual species of the genus are derived from perennials. The Malabar Gourd, C. ficifolia, is placed as a basal, sister taxon relative to other domesticated species and allied wild-types. The pattern of variation supports three species groups as monophyletic: (1) C. fraterna, C. pepo, and C. texana, (2) C. lundelliana, C. martinezii, C. mixta, C. moschata and C. sororia, and (3) C. foetidissima and C. pedatifolia. Domesticated samples representing subspecies of C. pepo are divided into two concordant groups, one of which is allied to wild-types referable to C. texana and C. fraterna. The data failed to resolve relationships among cultivars of C. moschata and C. mixta and their association to the wild C. sororia. The South American domesticate, C. maxima, and its companion weed, C. andreana, show close affinity and alliance to C. equadorensis.
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    URL: http://dx.doi.org/10.1007/BF00227397
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    Effects of stripe rust on the evolution of genetically diverse wheat populations (1993)
    Springer
    Theoretical and applied genetics 85 (1993), S. 809-821 
    Details
    ISSN: 1432-2242
    Keywords: Evolution ; Frequency-dependence ; Pathogens ; Host diversity ; Equilibrium frequencies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Eighteen populations, composed of four wheat (Triticum aestivum) varieties that were originally mixed together at equal frequencies, were grown for one-to-three generations at two locations. In addition, pure stands of the four varieties were grown in each year. Populations were either exposed to two stripe rust (Puccinia striiformis) races, protected from stripe rust, or exposed to alternating years of diseased and disease-free conditions. Regression of the logit of a variety's frequency versus generation number was used to calculate the relative fitness of each variety in each population. These analyses suggest that the relative fitnesses of the wheat varieties were affected by disease and geographic location and were constant over time. However, frequency-changes of varieties in the mixtures were negatively correlated with their planting frequencies (0.0001 〈 P 〈 0.085 in 14 out of 16 cases), suggesting that fitnesses were frequency-dependent in both the presence and absence of disease. We hypothesize that failure to detect frequency-dependence of fitness in the logit analyses was due to a limited number of generations and a limited range of initial variety frequencies. This is supported by data from longer-term studies in the literature that provide evidence for frequency-dependence of fitness in plant mixtures. Analyses of currently available field data suggest that stable equilibria may be a more likely outcome for mixtures of varieties that are more closely related and/or more uniformly adapted to the environment in which they are grown.
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    URL: http://dx.doi.org/10.1007/BF00225023
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    Development of synthetic Brassica amphidiploids by reciprocal hybridization and comparison to natural amphidiploids (1993)
    Springer
    Theoretical and applied genetics 86 (1993), S. 811-821 
    Details
    ISSN: 1432-2242
    Keywords: Brassica ; Interspecific hybridization ; Amphidiploid ; RFLP ; Evolution ; Nuclear ; cytoplasmic interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a previous study we proposed that cytoplasmic genomes have played an important role in the evolution of Brassica amphidiploid species. Based on this and other studies, we hypothesized that interactions between the maternal cytoplasmic genomes and the paternal nuclear genome may cause alterations in genome structure and/or gene expression of a newly synthesized amphidiploid, which may play an important role in the evolution of natural amphidiploid species. To test this hypothesis, a series of synthetic amphidiploids, including all three analogs of the natural amphidiploids B. napus, B. juncea, and B. Carinata and their reciprocal forms, were developed. These synthetic amphidiploids were characterized for morphological traits, chromosome number, and RFLPs revealed by chloroplast, mitochondrial, and nuclear DNA clones. The maternal transmission of chloroplast and mitochondrial genomes was observed in all of the F1 hybrids examined except one hybrid plant derived from the B. rapa x B. oleracea combination, which showed a biparental transmission of organelles. However, the paternal chloroplast and mitochondrial genomes were not observed in the F2 progeny. Nuclear genomes of synthetic amphidiploids had combined RFLP patterns of their parental species for all of the nuclear DNA clones examined. A variation in fertility was observed among self-pollinated progenies of single amphidiploids that had completely homozygous genome constitutions. Comparisons between natural and synthetic amphidiploids based on restriction fragment length polymorphism (RFLP) patterns indicated that natural amphidiploids are considerably more distant from the progenitor diploid species than the synthetic amphidiploids. The utility of these synthetic amphidiploids for investigating the evolution of amphidiploidy is discussed.
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    URL: http://dx.doi.org/10.1007/BF00212606
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    PCR analysis of genes encoding allelic variants of high-molecular-weight glutenin subunits at the Glu-D1 locus (1994)
    Springer
    Theoretical and applied genetics 88 (1994), S. 175-180 
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    ISSN: 1432-2242
    Keywords: HMW-glutenin genes ; Electrophoresis ; Polymerase chain reaction ; Molecular weight determination ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genes encoding high-molecular-weight (HMW) glutenin subunits, present in bread-wheat lines and cultivars, were studied by RFLP (restriction fragment length polymorphism) and PCR (polymerase chain reaction) analyses. In particular, allelic subunits of the x-or y-type, encoded at the Glu-D1 locus present on the long arm of chromosome 1D, were investigated. The variation in size, observed in different allelic subunits, is mainly due to variation in the length of the central repetitive domain, typical of these proteins. Deletions or duplications, probably caused by unequal crossingover, have given rise to the size heterogeneity currently observed. The possibility of using the PCR technique for a detailed analysis of HMW glutenin genes in order to obtain a more accurate estimation of the molecular weight of their encoded subunits, and the detection of unexpressed genes, is also described.
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    URL: http://dx.doi.org/10.1007/BF00225894
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    Chromosome assortment in Saccharum (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 959-963 
    Details
    ISSN: 1432-2242
    Keywords: Sugarcane ; Polyploidy ; Genetics ; Evolution ; Breeding ; DNA markers ; Arbitrarily primed PCR ; RAPD markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recent work has revealed random chromosome pairing and assortment in Saccharum spontaneum L., the most widely distributed, and morphologically and cytologically variable of the species of Saccharum. This conclusion was based on the analysis of a segregating population from across between S. spontaneum ‘SES 208’ and a spontaneously-doubled haploid of itself, derived from anther culture. To determine whether polysomic inheritance is common in Saccharum and whether it is observed in a typical biparental cross, we studied chromosome pairing and assortment in 44 progeny of a cross between euploid, meiotically regular, 2n=80 forms of Saccharum officinarum ‘LA Purple’ and Saccharum robustum ‘ Mol 5829’. Papuan 2n=80 forms of S. robustum have been suggested as the immediate progenitor species for cultivated sugarcane (S. officinarum). A total of 738 loci in LA Purple and 720 loci in Mol 5829 were amplified and typed in the progeny by arbitrarily primed PCR using 45 primers. Fifty and 33 single-dose polymorphisms were identified in the S. officinarum and S. robustum genomes, respectively (χ 2 at 98%). Linkage analysis of single-dose polymorphisms in both genomes revealed linkages in repulsion and coupling phases. In the S. officinarum genome, a map hypothesis gave 7 linkage groups with 17 linked and 33 unlinked markers. Four of 13 pairwise linkages were in repulsion phase and 9 were in coupling phase. In the S. robustum genome, a map hypothesis gave 5 linkage groups, defined by 12 markers, with 21 markers unlinked, and 2 of 9 pairwise linkages were in repulsion phase. Therefore, complete polysomic inheritance was not observed in either species, suggesting that chromosomal behavior is different from that observed by linkage analysis of over 500 markers in the S. spontaneum map. Implications of this finding for evolution and breeding are discussed.
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    URL: http://dx.doi.org/10.1007/BF00224524
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    Characterization of a family of tandemly repeated DNA sequences in Triticeae (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 217-225 
    Details
    ISSN: 1432-2242
    Keywords: Evolution ; Tandemly repeated DNA sequences ; Phylogenetic relationships ; RFLP ; Poaceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The recombinant plasmid dpTa1 has an insert of relic wheat DNA that represents a family of tandemly organized DNA sequences with a monomeric length of approximately 340 bp. This insert was used to investigate the structural organization of this element in the genomes of 58 species within the tribe Triticeae and in 7 species representing other tribes of the Poaceae. The main characteristic of the genomic organization of dpTa1 is a classical ladder-type pattern which is typical for tandemly organized sequences. The dpTa1 sequence is present in all of the genomes of the Triticeae species examined and in 1 species from a closely related tribe (Bromus inermis, Bromeae). DNA from Hordelymus europaeus (Triticeae) did not hybridize under the standard conditions used in this study. Prolonged exposure was necessary to obtain a weak signal. Our data suggest that the dpTa1 family is quite old in evolutionary terms, probably more ancient than the tribe Triticeae. The dpTa1 sequence is more abundant in the D-genome of wheat than in other genomes in Triticeae. DNA from several species also have bands in addition to the tandem repeats. The dpTa1 sequence contains short direct and inverted subrepeats and is homologous to a tandemly repeated DNA sequence from Hordeum chilense.
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    URL: http://dx.doi.org/10.1007/BF00225145
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    A study of genetic variation and evolution of Phyllostachys (Bambusoideae: Poaceae) using nuclear restriction fragment length polymorphisms (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 265-270 
    Details
    ISSN: 1432-2242
    Keywords: Bamboo ; Phyllostachys ; RFLP ; Variation ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phylogenetic and taxonomic difficulties are common within the woody bamboos, due to their unique life cycle, which severely limits the availability of floral characters. To addresss some of these problems, 20 species of woody bamboos in the genus Phyllostachys were analyzed using nuclear restriction fragment length polymorphisms (RFLPs). The RFLP data were used to generate genetic distances between all pairs of taxa and to examine the degree of genetic variation within and among bamboo species. The genetic distances were also used to create dendrograms of accessions and species. These trees supported the current division of the genus into two sections and provided some information on the thorny taxonomic problems in this group. We show that RFLPs can be used for species identification and the delineation of species limits.
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    URL: http://dx.doi.org/10.1007/BF00225152
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    Chloroplast DNA evolution in potato (Solanum tuberosum L.) (1991)
    Springer
    Theoretical and applied genetics 81 (1991), S. 13-20 
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    ISSN: 1432-2242
    Keywords: Potato ; Chloroplast DNA ; Sequence comparison ; Nucleotide substitution rate ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A deletion specific to chloroplast (ct) DNA of potato (Solanum tuberosum ssp. tuberosum) was determined by comparative sequence analysis. The deletion was 241 bp in size, and was not flanked by direct repeats. Five small, open reading frames were found in the corresponding regions of ctDNAs from wild potato (S. tuberosum ssp. andigena) and tomato (Lycopersicon esculentum). Comparison of the sequences of 1.35-kbp HaeIII ctDNA fragments from potato, tomato, and tobacco (Nicotiana tabacum) revealed the following: the locations of the 5′ ends of both rubisco large subunit (rbcL) and ATPase beta subunit (atpβ) mRNAs were probably the same as those of spinach (Spinacia oleracea); the promoter regions of the two genes were highly conserved among the four species; and the 5′ untranslated regions diverged at high rates. A phylogenetic tree for the three potato cultivars, one tomato cultivar, and one tobacco cultivar has been constructed by the maximum parsimony method from DNA sequence data, demonstrating that the rate of nucleotide substitution in potato ctDNA is much slower than that in tomato ctDNA. This fact might be due to the differences in the method of propagation between the two crops.
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    URL: http://dx.doi.org/10.1007/BF00226106
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    Diversity and origins of endophytic fungal symbionts of the North American grass Festuca arizonica (1992)
    Springer
    Theoretical and applied genetics 85 (1992), S. 366-371 
    Details
    ISSN: 1432-2242
    Keywords: rRNA gene ; Epichloë typhina (Acremonium typhinum) ; Evolution ; Population ; Parsimony analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Acremonium spp. endophytes are mutualistic fungal symbionts of many C3 grasses. They are anamorphs of Epichloë typhina (Clavicipitaceae) that have become strictly seedborne, heritable components of symbiotic units (“symbiota”). In order to test the possibility that endophytes may contribute to the genetic diversity of symbiota, a survey was conducted of plants from nine populations of Festuca arizonica in the southern Rocky Mountains. Sequence analysis of rRNA gene segments distinguished three Acremonium endophyte types. Parsimony analysis indicated at least two distinct evolutionary origins of the Acremonium endophytes from E. typhina. Either or both of these evolutionary lineages may have involved cospeciation with the host.
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    URL: http://dx.doi.org/10.1007/BF00222883
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    Investigations on the relations within the family papilionaceae on the basis of electrophoretic banding patterns (1980)
    Springer
    Theoretical and applied genetics 57 (1980), S. 225-232 
    Details
    ISSN: 1432-2242
    Keywords: Electrophoresis ; Proteins ; Leguminosae ; Taxonomy ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Gel electrophoretic investigations were made on the seed albumins of several members of the family Papilionaceae. Relationships were found with taxa of a lower order i.e. between mutants, varieties and subspecies. More distantly related ones, for example species of the same genus or species of different genera, did not show similarities. Thus, it was concluded that the albumin banding pattern is only suitable for studying phylogenetic and taxonomic problems if the material under investigation is not too distantly related.
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    URL: http://dx.doi.org/10.1007/BF00264675
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    Cross-incompatibility between two sympatric polyploid Solanum species (1981)
    Springer
    Theoretical and applied genetics 60 (1981), S. 65-70 
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    ISSN: 1432-2242
    Keywords: Cross-incompatibility ; Solanum ; Reproductive barriers ; Introgression ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Preliminary results from a large number of reciprocal crosses between the closely related sympatric species S. gourlayi Hawkes (2n=4x=48) and S. oplocense Hawkes (2n=6x=72) indicated that they are difficult to hybridize. Pollen-pistil incompatibility barriers were detected via fluorescent microscopy. The cross incompatibility reaction occurred at three sites in 6x×4x crosses; on the stigma, in the first one-third of the style, and in the first two-thirds of the style. In the reciprocal 4x×6x crosses the incompatibility reaction invariably occurred in the ovary. Backcrosses of interspecific pentaploid hybrids (that were occasionally formed) to both parental populations were fully compatible, partially compatible, and fully incompatible with three sites of cross-incompatibility reaction similar to those observed in 6x×4x crosses, respectively. Both polyploid species were found to be selfcompatible, whereas their F1 hybrids were found to be self-incompatible. An hypothesis based on interactions of dominant cross-incompatibility (CI) genes in pistils and dominant specific complementary genes in pollen grains is postulated to explain these observations. The cross-incompatibility system that appears to be operating in nature between 4x S. gourlayi and 6x S. oplocense provides a way for gene exchange between sympatric populations without threatening the identity of either species.
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    URL: http://dx.doi.org/10.1007/BF00282417
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    Nicotiana chloroplast genome III. Chloroplast DNA evolution (1982)
    Springer
    Theoretical and applied genetics 61 (1982), S. 73-79 
    Details
    ISSN: 1432-2242
    Keywords: Nicotiana ; Chloroplast DNA ; Restriction fragments ; Deletion ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Nicotiana chloroplast genomes exhibit a high degree of diversity and a general similarity as revealed by restriction enzyme analysis. This property can be measured accurately by restriction enzymes which generate over 20 fragments. However, the restriction enzymes which generate a small number (about 10) of fragments are extremely useful not only in constructing the restriction maps but also in establishing the sequence of ct-DNA evolution. By using a single enzyme, Sma I, a elimination and sequential gain of its recognition sites during the course of ct-DNA evolution is clearly demonstrated. Thus, a sequence of ct-DNA evolution for many Nicotiana species is formulated. The observed changes are all clustered in one region to form a “hot spot” in the circular molecule of ct-DNA. The mechanisms involved for such alterations are mostly point mutations but inversion and deficiency are also indicated. Since there is a close correlation between the ct-DNA evolution and speciation in Nicotiana a high degree of cooperation and coordination betwen organellar and nuclear genomes is evident.
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    URL: http://dx.doi.org/10.1007/BF00261515
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    Origin and evolution of cultivated tetraploid potatoes via 2n gametes (1982)
    Springer
    Theoretical and applied genetics 61 (1982), S. 161-169 
    Details
    ISSN: 1432-2242
    Keywords: Cultivated potato ; Evolution ; Parallel spindles ; 2n gametes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A high gene frequency for ps (parallel spindles) is expected in cultivated tetraploid potatoes, S. tuberosum Group Tuberosum, if 2n pollen produced by ancestral diploid plants which were psps was involved in the origin and evolution of the potato. Fifty-six North American cultivars (varieties and advanced selections) were pollinated by diploid clones, either W 5295.7 or W 5337.3 which are homozygous recessive for ps. The segregation ratios in regard to 2n pollen production in derived tetraploid progenies, from 4x×2x crosses, reveal the genotype of ps in the cultivars. Microsporogenesis of 2n pollen producing 4x progeny was observed to avoid an overestimation of the frequency of 2n pollen producing plants due to mechanisms other than parallel spindles. More than 50% of the 56 cultivars are simplex (Pspspsps), since in each of these cultivars about 50% of their progeny produced 2n pollen. The ps gene frequency in the 56 cultivars was estimated as high as 0.69. The high frequency of ps in the tetraploid cultivars clearly supports the hypothesis that 2n pollen produced by plants homozygous recessive for ps have been involved in the origin of cultivated tetraploid potatoes, since a higher frequency of ps in the tetraploid than in the ancestral diploid population can be expected from sexual polyploidization but not from somatic doubling. The importance of meiotic mutants such as ps for the successful evolution of polysomic polyploids is emphasized.
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    URL: http://dx.doi.org/10.1007/BF00273885
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    Utilization of wild relatives in genetic improvement of Arachis hypogaea L. (1982)
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    Theoretical and applied genetics 61 (1982), S. 305-314 
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    ISSN: 1432-2242
    Keywords: Arachis ; Karyomorphology ; D2 analysis and genetic distance ; Evolution ; Crop improvement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The chromosome complements of 12 taxa in section Arachis were karyotypically and meiotically analysed. In taxa with 2n=20 the arm ratio of the respective pair of chromosomes was taken as an independent quantitative character and statistically analysed by Mahalanobis D2. Two clusters were formed, one represented solely by A. batizocoi and the other consisting of the remaining 11 taxa. This grouping was confirmed by canonical analysis. In the larger group of species, A villosa and A. correntina were closely related karyotypically and on D2 distance, while A. cardenasii forms a distinct subgroup. A. cardenasii lacks the short “A” chromosome recorded in other species of this group, and A. batizocoi is no longer the only species to have a pair of chromosomes with a secondary constriction. The taxa with 2n=40, A. monticola and A. hypogaea, are karyotypically very similar, though there is a difference in the number of chromosome pairs with a secondary constriction. On the basis of karyomorphological affinity, especially in relation to marker chromosomes, A. cardenasii is probably one of the ancestors of the tetraploid species studied.
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    Length variation in the internal transcribed spacers of ribosomal DNA in Picea abies and related species (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 969-974 
    Details
    ISSN: 1432-2242
    Keywords: Evolution ; rDNA ; Internal transcribed spacers ; Picea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The structure and variation of nuclear ribosomal DNA (rDNA) units of Picea abies, (L.) Karst. was studied by restriction mapping and Southern hybridization. Conspicuous length variation was found in the internal transcribed spacer (ITS) region of P. abies, although the length of this region is highly conserved both within and among most of the plant species. Two types of ITS variants (A and B), displaying a size difference of 0.5 kb in the ITS2 region, were present within individuals of P. abies from Sweden, Central Europe and Siberia. A preliminary survey of 14 additional Eurasian and North American species of Picea suggested that length variation in the ITS region is widespread in this genus. Alltogether three length variants (A, B and C) were identified. Within individuals of eight Picea species, two length variants were present within the genome (combinations of A and B variants in P. glehnii, P. maximowiczii, P. omorika, P. polita and P. sitchensis and variants B and C in P. jezoensis, P. likiangensis and P. spinulosa). Within individuals from five species, however only one rDNA variant was present in their genome (variant A in P. aurantiaca, P. engelmannii, P. glauca, P. koraiensis and P. koyamai; variant B in P. bicolor). The ITS length variation will be useful as a molecular marker in evolutionary studies of the Picea species complex, whose phylogeny is controversial. The presence of intraindividual variation in, and shared polymorphism of the, ITS length variants raises questions about the occurrence of interspecific hybridization during the evolutionary history of Picea.
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    URL: http://dx.doi.org/10.1007/BF00224526
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    The occurrence and frequency of 2n pollen in three diploid solanums from Northwest Argentina (1980)
    Springer
    Theoretical and applied genetics 56 (1980), S. 11-15 
    Details
    ISSN: 1432-2242
    Keywords: Diploid pollen ; Evolution ; Sexual polyploidization ; Solanum ; Tuberosa ; Diplandroids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A group of wild, tuber-bearing species from Northwest Argentina, belonging to the series Tuberosa, Solarium spegazzini Bitt. (spg, 2n=2x=24), S. gourlayi Hawkes (grl, 2n=2x=24 and 2n=4x=48) and S. oplocense Hawkes (opl, 2n=6x=72), and Cuneolata, S. infundibuliforme Phil (ifd, 2n=2x=24), is being used to investigate the mode of origin of polyploids in the genus Solanum. 2n gametes have been detected in the diploid species ifd and spg and in a diploid race of grl, using cytological and breeding approaches. Twenty-two introductions of spg, 8 of grl and 26 of ifd have been tested for 2n pollen; 59%, 63% and 54% of them, respectively, had at least one 2n pollen producing plant. These introductions comprised 238, 76 and 235 plant respectively, of which 20, 16, and 32 plant produced 5% or more 2n pollen. The mechanism of 2n pollen formation was determined in several plant of 2x spg, 2x grl and 2x ifd. All of them were found to form diplandroids via parallel spindles. This mechanism, which gives meiotic products genetically equivalent to first division restitution gametes, is under control of the Mendelian recessive ps. The results suggest that the allele ps is widely distributed in natural populations of the three diploids, and that its frequency is very high. These species are seen as valuable material for population genetic studies, and for the eventual incorporation into a breeding scheme involving sexual polyploidization via 2n gametes.
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    URL: http://dx.doi.org/10.1007/BF00264421
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    The significance of genic balance to endosperm development in interspecific crosses (1980)
    Springer
    Theoretical and applied genetics 57 (1980), S. 5-9 
    Details
    ISSN: 1432-2242
    Keywords: Endosperm ; Evolution ; Interspecific crosses ; Solanums ; 2n gametes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The endosperm has played a significant role in the evolution of angiosperms because of its physiological and genetic relationships to the embryo. One manifestation of this evolutionary role is its abnormal development in interploidy crosses. It is now established that the endosperm develops abnormally in interploidy-intraspecific crosses when the maternal: paternal genome ratio deviates from 2∶1 in the endosperm itself. We propose an Endosperm Balance Number (EBN) hypothesis to explain endosperm development in both interploidy-intraspecific and interspecific crosses. Each species is assigned an EBN on the basis of its crossing behavior to a standard species. It is the EBN which determines the effective ploidy in the endosperm of each species, and it is the EBNs which must be in a 2∶1, maternal:paternal ratio. The EBN of a species may be determined by a few genes rather than the whole genome. This hypothesis brings most intraspecific-interploidy and interspecific crossing data under a single concept with respect to endosperm function. The implications of this hypothesis to isolating mechanisms, 2n gametes, the evolution of disomic polyploids, and reciprocal differences in seed development are discussed.
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    URL: http://dx.doi.org/10.1007/BF00276002
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    Cytophotometrical measurement of nuclear DNA content in some coniferous and deciduous trees (1980)
    Springer
    Theoretical and applied genetics 58 (1980), S. 187-191 
    Details
    ISSN: 1432-2242
    Keywords: Conifers ; Deciduous tree ; Polyploidy ; Endoploidy ; Evolution ; Cytophotometry ; DNA content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The DNA content of nuclei from meristematic root tip cells of five coniferous and one deciduous tree species and, for comparison, ofVicia faba was cytophotometrically determined. The DNA values of diploid nuclei fromGinkgo biloba are approximately a quarter lower than those fromVicia faba. The nuclear DNA values of the other tree species are merely a third to a ninth part of those ofVicia faba. In three tree species, as well as diploid, we have found nuclei of different polyploid level. The reliability of different cytochemical methods, which are used for determination of the nuclear DNA content, is critically analyzed. The DNA values of the investigated tree species are discussed in connection with the evolution of the DNA content in higher plants.
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    URL: http://dx.doi.org/10.1007/BF00279713
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    “Complement fractionation” in natural diploid orchid species (1982)
    Springer
    Theoretical and applied genetics 61 (1982), S. 91-95 
    Details
    ISSN: 1432-2242
    Keywords: Complement fractionation ; Excess sporads ; Diploid orchid species ; Phaius tribe ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Four out of 10 diploid orchid species showed “complement fractionation” a complex cytological phenomenon, hitherto reported only in polyploid plants. The manifestation of this phenomenon during meiosis is the formation of chromosome subgroups resulting eventually in cells with more than the usual four sporads; five or six being the optimum number in the investigated orchid species. No implications whatsoever can be deduced as to the genetic or genomic constitution of the end products. The presence of the phenomenon in these orchid species could perhaps indicate a polyploid ancestry or concealed hybridity. The operation of “complement fractionation”, however, could be interpreted as an alternative evolutionary pathway opposed to polyploidy.
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    URL: http://dx.doi.org/10.1007/BF00261517
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    Chromosome and nucleotide sequence differentiation in genomes of polyploid Triticum species (1982)
    Springer
    Theoretical and applied genetics 63 (1982), S. 349-360 
    Details
    ISSN: 1432-2242
    Keywords: Chromosomes ; Nucleotides ; Evolution ; Polyploids ; Triticum ; Heterochromatin ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nature of genome change during polyploid evolution was studied by analysing selected species within the tribe Triticeae. The levels of genome changes examined included structural alterations (translocations, inversions), heterochromatinization, and nucleotide sequence change in the rDNA regions. These analyses provided data for evaluating models of genome evolution in polyploids in the genus Triticum, postulated on the basis of chromosome pairing at metaphase I in interspecies hybrids. The significance of structural chromosome alterations with respect to reduced MI chromosome pairing in interspecific hybrids was assayed by determining the incidence of heterozygosity for translocations and paracentric inversions in the A and B genomes of T. timopheevii ssp. araraticum (referred to as T. araraticum) represented by two lines, 1760 and 2541, and T. aestivum cv. Chinese Spring. Line 1760 differed from Chinese Spring by translocations in chromosomes 1A, 3A, 4A, 6A, 7A, 3B, 4B, 7B and possibly 2B. Line 2541 differed from Chinese Spring by translocations in chromosomes 3A, 6A, 6B and possibly 2B. Line 1760 also differed from Chinese Spring by paracentric inversions in arms 1AL and 4AL whereas line 2541 differed by inversions in 1BL and 4AL (not all chromosomes arms were assayed). The incidence of structural changes in the A and B genomes did not coincide with the more extensive differentiation of the B genomes relative to the A genomes as reflected by chromosome pairing studies. To assay changing degrees of heterochromatinization among species of the genus Triticum, all the diploid and polyploid species were C-banded. No general agreement was observed between the amount of heterochromatin and the ability of the respective chromosomes to pair with chromosomes of the ancestral species. Marked changes in the amount of heterochromatin were found to have occurred during the evolution of some of the polyploids. The analysis of the rDNA region provided evidence for rapid “fixation” of new repeated sequences at two levels, namely, among the 130 bp repeated sequences of the spacer and at the level of the repeated arrays of the 9 kb rDNA units. These occurred both within a given rDNA region and between rDNA regions on nonhomologous chromosomes. The levels of change in the rDNA regions provided good precedent for expecting extensive nucleotide sequence changes associated with differentiation of Triticum genomes and these processes are argued to be the principal cause of genome differentiation as revealed by chromosome pairing studies.
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    URL: http://dx.doi.org/10.1007/BF00303906
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    Evolutionary analysis of Pinus densata (Masters), a putative Tertiary hybrid. (1990)
    Springer
    Theoretical and applied genetics 80 (1990), S. 641-647 
    Details
    ISSN: 1432-2242
    Keywords: Pinus ; Species hybridization ; Chloroplast DNA ; Molecular markers ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Restriction fragment analysis and heterologous hybridization of chloroplast (cp) DNA was used to develop species-specific markers for P. tabulaeformis, P. yunnanensis and P. massoniana. Fragment patterns created by the BclI and DraI restriction enzymes and hybridization patterns to the psbC and psbD probes were distinctive among the three species. No intraspecific variation was detected with respect to any of the cpDNA markers developed in this study. The cpDNA markers obtained were subsequently used to examine the parentage of P. densata, a putative Tertiary hybrid between P. tabulaeformis and P. yunnanensis. The analysis demonstrated for the first time that P. densata populations accommodate chloroplast genomes of P. tabulaeformis and P. yunnanensis, which strongly supports earlier suggestions of the hybrid origin of this species. It appears that P. densata represents a stabilized natural hybrid that has become adapted to high mountain environments where neither of the parental species can normally grow.
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    URL: http://dx.doi.org/10.1007/BF00224224
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    Evolutionary analysis of Pinus densata Masters, a putative Tertiary hybrid (1990)
    Springer
    Theoretical and applied genetics 80 (1990), S. 635-640 
    Details
    ISSN: 1432-2242
    Keywords: Pinus ; Species hybridization ; Allozymes ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Allozyme differentiation at 13 loci was studied in populations of Pinus tabulaeformis, P. densata, and P. yunnanensis from China. It was previously suggested that P. densata represents a Tertiary hybrid between P. tabulaeformis and P. yunnanensis. The observed levels of allozyme variation within and among the investigated species were comparable to those of other conifers. P. tabulaeformis differed markedly from P. yunnanensis with respect to allozyme frequencies, while P. densata was intermediate between the two putative parents. There was evidence of homozygote excess in embryos from all investigated species, as compared to Hardy-Weinberg expectations. The observed allozyme composition of P. densata conformed to earlier morphological and molecular evidence indicating hybrid origin of this taxon. It was proposed that fusion of gene pools from P. tabulaeformis and P. yunnanensis has led to adaptive evolution of a new species, P. densata.
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    URL: http://dx.doi.org/10.1007/BF00224223
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    Distribution and organization of a tandemly repeated 352-bp sequence in the oryzae family (1991)
    Springer
    Theoretical and applied genetics 82 (1991), S. 57-64 
    Details
    ISSN: 1432-2242
    Keywords: Cultivated rice ; Wild rice ; RFLP ; Satellite DNA ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A 352-bp EcoRI fragment from rice DNA was cloned and shown to be a member of a tandem repeat. Sequence determination revealed homologies with human alpha satellite DNA and maize knob heterochromatin specific repeat. This 352-bp sequence is highly specific for the AA genome of rice. However, copy number and sequence organization are variable, depending on the accession analyzed. Several examples of amplification were observed in O. rufipogon and O. longistaminata. Use of resolutive polyacrylamide gel electrophoresis and 4-bp cutter enzymes allowed one to distinguish between the Indica and Japonica subtypes of O. sativa. The same method also discriminates between two groups of O. rufipogon, the presumed ancestor of O. sativa, suggesting that the present day Indica and Japonica subtypes originated independently from two O. rufipogon distinct populations.
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    URL: http://dx.doi.org/10.1007/BF00231278
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    Taxonomic and evolutionary implications of the Endosperm Balance Number hypothesis in potatoes (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 180-185 
    Details
    ISSN: 1432-2242
    Keywords: Potato ; Solanum ; Endosperm Balance Number (EBN) ; Taxonomy ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Endosperm Balance Number (EBN) hypothesis can explain to a considerable degree the crossability between tuber-bearing Solanum species. It has been shown to be genetically controlled and is dosage dependent. There is a good correlation between EBN and the postulated evolution and present taxonomy of potatoes. The primitive white stellate-flowered species from Mexico are 1EBN, and this condition is also found in species from South America with flowers of the same colour and shape. The evolution of a rotate corolla seems to be correlated with 2EBN. It is postulated that the 2EBN state arose as a reproductive isolating mechanism in South America. The taxonomic and evolutionary implications of the EBN hypothesis are discussed.
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    URL: http://dx.doi.org/10.1007/BF00223998
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    RFLP-based phylogeny of Musa species in Papua New Guinea (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 579-584 
    Details
    ISSN: 1432-2242
    Keywords: Fe'i bananas ; Taxonomy ; Evolution ; M. acuminata ; M. fehi ; M. banksii ; RFLP ; Papua New Guinea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Random genomic probes were used to detect restriction fragment length polymorphisms (RFLPs) in 26 accessions of Musa representing eight species from Papua New Guinea (PNG), M. textilis, M. jackeyi and one accession of Ensete. Ninety-eight phylogenetically informative characters were scored and analyzed cladistically and phenetically. Results generally agreed with previous morphology-based phylogenetic analyses. However, the closest wild relative of the edible M. fehi (fe'i banana) appears to be M. lolodensis. Musa angustigemma is sister species with M. boman and M. jackeyi and is distinct from M. peekelii, with which it is often united. Musa boman is unambiguously placed in section Australimusa. The diploid parthenocarpic landraces of section Musa unique to PNG are closely related to, but apparently distinct from, M. acuminata ssp. banksii. The evolution of the fe'i bananas and the M. acuminata-derived diploid landraces of PNG are discussed.
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    URL: http://dx.doi.org/10.1007/BF00224155
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    Analysis of a genomic DNA segment carrying the wheat high-molecular-weight (HMW) glutenin Bx17 subunit and its use as an RFLP marker (1993)
    Springer
    Theoretical and applied genetics 85 (1993), S. 616-624 
    Details
    ISSN: 1432-2242
    Keywords: Wheat ; Glutenin ; Dough ; Evolution ; RFLPs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A genomic fragment containing the Bx17 high-molecular-weight (HMW) glutenin gene was isolated from a wheat genomic library. The fragment contains a coding region of 2.82kb with 1.98-kb downstream and 12.8-kb upstream flanking regions. The fragment was sequenced and compared with previously published glutenin genes from chromosomes 1A, 1B and 1D using a computer alignment package. The Bx17 gene shows marked similarity to the Bx7 gene sequence. A phenetic tree derived from the alignments is presented. Also shown are restriction fragment length polymorphisms (RFLPs) at the glutenin loci in a set of Australian and international wheat varieties using different regions of the glutenin clone as probes. The RFLPs correlated well with the protein composition in all cultivars analysed.
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    URL: http://dx.doi.org/10.1007/BF00220921
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    Molecular systematics and genetic differentiation of Pinus sylvestris (L.) and P. densiflora (Sieb. et Zucc.) (1993)
    Springer
    Theoretical and applied genetics 86 (1993), S. 159-165 
    Details
    ISSN: 1432-2242
    Keywords: Allozymes ; Chloroplast DNA ; Introgression ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Allozyme variation was examined in 22 populations of Pinus densiflora (Sieb, et Zucc.) and four geographic varieties of P. sylvestris (L.): var ‘lapponica’ (Fries, Hartman), var ‘armena’ (Komarov), var ‘mongolica’ (Litvinov) and var ‘sylvestriformis’ (Takenouchi). In addition, we developed paternal chloroplast (cp) DNA markers that distinguish P. densiflora from var ‘lapponica’, var ‘armena’ and var ‘mongolica’. UPGMA cluster analysis based on Nei's distances between all pairwise combinations of the 22 populations revealed patterns corresponding strictly to geographic origin and taxonomic status. Analysis of allozyme variation in var ‘lapponica’, var ‘armena’ and var ‘mongolica’ demonstrated a high level of intrapopulational variability but a low level of interpopulational differentiation. It appears that the late Pleistocene blending of genetically diverse populations was responsible for the observed variation patterns. The constructed phylogenetic trees also showed late divergence of these three varieties. The var ‘sylvestri formis’ was genetically distinct from the other three P. sylvestris varieties. The genetic distances separating var ‘sylvestriformis’ from P. densiflora and the other taxa lend support to a separate taxonomic status for var ‘sylvestriformis’ and a close relation with P. densiflora. We found that var ‘sylvestriformis’ harbors admixtures of allozymes and cpDNA from both P. sylvestris and P. densiflora, which suggests an introgressive nature of this variety. Levels of intrapopulational variability were similar in P. sylvestris and P. densiflora, but interpopulational differentiation was much higher in P. densiflora. In the constructed phylogenetic trees, populations of this species were characterized by relatively long internode distances and branch lengths. The present results suggest that P. densiflora has a more advanced evolutionary age than P. sylvestris.
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    URL: http://dx.doi.org/10.1007/BF00222074
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    Phylogenetic relationships between cultivated and wild species of the genusBeta revealed by DNA “fingerprinting” (1993)
    Springer
    Theoretical and applied genetics 86 (1993), S. 449-457 
    Details
    ISSN: 1432-2242
    Keywords: Sugar beet ; Beta species ; DNA “finger-printing” ; Cluster analysis ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Forty-one accessions of the genusBeta representing wild and cultivated species of all sections were analyzed by DNA “fingerprinting”. Four sugar beet minisatellite DNA probes revealed characteristic banding patterns with Southern-hybridizedBeta DNA restricted withHindIII. A total of 111 polymorphic RFLP bands were scored across all accessions. Cluster analysis based on genetic similarity estimates for all 820 combinations of accessions revealed the following results. (1) All accessions could unambiguously be identified by a characteristic RFLP banding pattern. (2) The sugar beet cultivars examined displayed a low level of genetic diversity; they showed high similarity toB. Vulgaris ssp.maritima but low genetic similarity to the other wild species of section I. (3) In most cases, the present taxonomic classification of the genusBeta was confirmed. Species of sections II, III, and IV were clearly distinguishable from those of section I except forB. Macrocarpa, which showed high similarity to wild species of section II. In a second experiment, 108 single-copy RFLP probes from sugar beet were Southern hybridized withB. procumbens DNA. A surprisingly low degree of homology (34%) was found. The results are discussed with regard to the taxonomic classification of the genusBeta.
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    URL: http://dx.doi.org/10.1007/BF00838560
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    Origin, evolution and genome differentiation in Guizotia abyssinica and its wild species (1993)
    Springer
    Theoretical and applied genetics 87 (1993), S. 587-592 
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    ISSN: 1432-2242
    Keywords: Guizotia abyssinica ; Genome ; Interspecific hybridization ; Evolution ; Karyotype
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Guizotia abyssinica, G. schimperi and G. scabra are diploid species (2n=2x=30) characterised by 15 bivalents during prophase-I/metaphase-I of meiosis. The former species is cultivated whereas the latter two are wild. Interspecific hybrids between these three species were generated and the F1 hybrids were analysed to assess cytogenetic relationships and crop evolution within the genus Guizotia. Meiotic chromosome configurations at diakenesis/metaphase-I in the pollen mother cells of hybrids averaged 0.25I + 14.60II + 0.15IV for G. abyssinica x G. schimperi, 0.05I + 13.6II + 0.14III + 0.58IV for G. abyssinica x G. scabra, and 0.8I + 12.7II + 0.08III + 0.88IV for G. schimperi x G. scabra. Based upon the results of our investigations we conclude that the genomes of G. abyssinica and G. schimperi are similar and homologous, whereas the G. scabra genome is only partially homologous to that of G. abyssinica/G. schimperi. Furthermore, the crop species G. abyssinica might have originated from G. schimperi through selection and cultivation; chromosome translocations appear to have played a significant role in the divergence and differentiation of these three species.
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    URL: http://dx.doi.org/10.1007/BF00221882
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    Phylogenetic analysis of chloroplast restriction enzyme site mutations in the Saccharinae Griseb. subtribe of the Andropogoneae Dumort. tribe (1994)
    Springer
    Theoretical and applied genetics 87 (1994), S. 843-853 
    Details
    ISSN: 1432-2242
    Keywords: Sugarcane ; Saccharm ; Evolution ; Cytoplasmic inheritance ; Restriction mapping ; Cladistics ; Parsimony ; Dollo parsimony ; Wagner parsiomony ; Maximum likelihood ; Saccharum complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chloroplast (cp) DNA from 32 genotypes representing eight genera and 19 species from the Andropogoneae tribe was analyzed using 15 restriction enzymes and Southern hybridization with 12 cpDNA probes that span the complete rice chloroplast genome. Six of the genera, Saccharum, Miscanthus, Erianthus, Narenga, Eccoilopus, and Sclerostachya, are part of the Saccharinae subtribe, whereas the other two, Zea and Sorghum, were used as outgroups. Narenga, Miscanthus, Erianthus, and Sclerostachya are presumed to have been involved in the evolution of Saccharum officinarum (“noble” or high sucrose sugarcane) via S. spontaneum and S. robustum. Southern hybridization with the rice cpDNA probes surveyed approximately 3% of the S. officinarum ‘Black Cheribon’ genome and yielded 62 restriction site mutations (18 informative) that were analyzed using cladistic parsimony and maximum likelihood. These site mutations placed the 32 genotypes into nine different chloroplast groups; seven from within the Saccharinae subtribe and the two outgroups (maize and Sorghum). Phylogenetic inferrence under various assumptions showed that the maternal lineages of Narenga, Miscanthus, Sclerostachya, and Saccharum formed a monophyletic group. This group displayed little variation. On the other hand, 5 of 6 Erianthus species and Eccoilopus longisetosus formed a separate group. The ‘Old World’ Erianthus/Eccoilopus chloroplast was very different from that of the rest of the ‘Saccharum complex’ members and was slightly more related to that of Sorghum bicolor. Placement of these Erianthus/Eccoilopus genotypes was, therefore, in conflict with analyses based on morphology. Surprisingly, Erianthus trinii, a New World species, had the same restriction sites as did one Miscanthus sinensis. One Miscanthus sp. from New Guinea that has a very high chromosome number (2n=192) had the same restriction sites as the majority of the Saccharum genus, suggesting that introgression between these genera occurs in the wild. The Saccharum genus was separated into two clades by single site mutation: one containing S. spontaneum, and the other containing all of the remaining Saccharum species and all 8 commerical hybrids (from various regions of the world). A physical map of the chloroplast of Saccharum officinarum ‘Black Cheribon’ was constructed using 5 restriction enzymes.
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    The generation of Mutator transposable element subfamilies in maize (1994)
    Springer
    Theoretical and applied genetics 87 (1994), S. 657-667 
    Details
    ISSN: 1432-2242
    Keywords: Transposable elements ; Mutation ; Evolution ; DNA repair ; Gene conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mobile DNAs of the Mutator system of maize (Zea mays) are exceptional both in structure and diversity. So far, six subfamilies of Mu elements have been discovered; all Mu elements share highly conserved terminal inverted repeats (TIRs), but each sub-family is defined by internal sequences that are apparently unrelated to the internal sequences of any other Mu subfamily. The Mu1/Mu2 subfamily of elements was created by the acquisition of a portion of a standard maize gene (termed MRS-A) within two Mu TIRs. Beside the unusually long (185–359 bp) and diverse TIRs found on all of these elements, other direct and inverted repeats are often found either within the central portion of a Mu element or within a TIR. Our computer analyses have shown that sequence duplications (mostly short direct repeats interrupted by a few base pairs) are common in non-autonomous members of the Mutator, Ac/Ds, and Spm(En) systems. These duplications are often tightly associated with the element-internal end of the TIRs. Comparisons of Mu element sequences have indicated that they share more terminal components than previously reported; all subfamilies have at least the most terminal 215 bp, at one end or the other, of the 359-bp Mu5 TIR. These data suggest that many Mu element subfamilies were generated from a parental element that had termini like those of Mu5. With the Mu5 TIRs as a standard, it was possible to determine that elements like Mu4 could have had their unusual TIRs created through a three-step process involving (1) addition of sequences to interrupt one TIR, (2) formation of a stem-loop structure by one strand of the element, and (3) a subsequent DNA repair/gene conversion event that duplicated the insertion(s) within the other TIR. A similar repair/conversion extending from a TIR stem into loop DNA could explain the additional inverted repeat sequences added to the internal ends of the Mu4 and Mu7 TIRs. This same basic mechanism was found to be capable of generating new Mu element subfamilies. After endonucleolytic attack of the loop within the stem-loop structure, repair/conversion of the gap could occur as an intermolecular event to generate novel internal sequences and, therefore, a new Mu element subfamily. Evidence supporting and expanding this model of new Mu element subfamily creation was identified in the sequence of MRS-A.
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    Polymorphisms in the α-amy1 gene of wild and cultivated barley revealed by the polymerase chain reaction (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 509-513 
    Details
    ISSN: 1432-2242
    Keywords: α-amylase ; Barley ; DNA polymorphism ; Evolution ; Polymerase chain reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract α-Amylases are the key enzymes involved in the hydrolysis of starch in plants. The polymerase chain reaction (PCR) was used to detect polymorphisms in the length of amplified sequences between the annealing sites of two primers derived from published α-amy1 gene sequences in barley. These two primers (Bsw1 and Bsw7), flanking the promoter region and the first exon, amplified two PCR fragments in barley. One of the amplified products, with the expected length of 820 bp, appeared together with another shorter PCR band of around 750 bp. This 750-bp fragment seems to be derived from an α-amylase gene not reported previously. Both of the PCR products could be amplified from the two-rowed barley varieties tested, including cv Himalaya from which the sequence information was obtained. Five of the six-rowed barley varieties also have the two PCR fragments whereas another two have only the long fragment. These two fragments seem to be unique to barley, neither of them could be amplified from other cereals; for example, wheat, rye or sorghum. These two α-amylase fragments were mapped to the long arm of 6H, the location of the α-amy1 genes, using wheat-barley addition lines. Amplification of genomic DNA from wild barley accessions with primers Bsw1 and Bsw7 indicated that both of the fragments could be present, or the long and short fragments could be present alone. The results also demonstrated that the genes specifying these two fragments could be independent from each other in barley. The conserved banding pattern of these two fragments in the two-rowed barley varieties implies that artificial selection from these genes may have played an important role in the evolution of cultivated barley from wild barley.
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    URL: http://dx.doi.org/10.1007/BF00225388
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    The metathoracic wing-hinge chordotonal organ of an atympanate moth, Actias luna (Lepidoptera, Saturniidae): a light- and electron-microscopic study (1992)
    Springer
    Cell & tissue research 267 (1992), S. 455-471 
    Details
    ISSN: 1432-0878
    Keywords: Chordotonal organ ; Scolopidium ; Homology ; Electron microscopy ; Sensilla ; Evolution ; Actias luna (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure of a simple chordotonal organ, the presumed homologue of the noctuoid moth tympanal organ, is described in the atympanate moth, Actias luna. The organ consists of a proximal scolopidial region and a distal strand, which attaches peripherally to the membranous cuticle ventral to the hindwing alula. The strand is composed of elongate, microtubule-rich cells encased in an extracellular connective tissue sheath. The scolopidial region houses three mononematic, monodynal scolopidia, each comprised of a sensory cell, scolopale cell, and attachment cell. The dendritic apex is octagonally shaped in transverse section, its inner membrane lined by a laminated structure reminiscent of the noctuoid tympanal organ ‘collar’. A 9+0-type cilium emerges from the dendritic apex, passes through both the scolopale lumen and cap, and terminates in an extracellular space distal to the latter. Proximal extensions of the attachment cell and distal prolongations of the scolopale cell surrounding the cap are joined by an elaborate desmosome, with which is associated an extensive electron-dense fibrillar plaque. Within the scolopale cell, this plaque constitutes the scolopale ‘rod’ material. The data are discussed in terms of both the organ's potential function, and its significance as the evolutionary proto-type of the noctuoid moth ear.
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    A comparative study of leucokinin-immunoreactive neurons in insects (1994)
    Springer
    Cell & tissue research 276 (1994), S. 69-83 
    Details
    ISSN: 1432-0878
    Keywords: Immunocytochemistry ; Vasopressin ; Diuresis ; Neurohemal organ ; Evolution ; Nauphoeta cinerea ; Aedes aegypti ; Acheta domesticus ; Schistocerca americana (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Antisera were raised against leucokinin IV, a member of the leucokinin peptide family. Immunohistochemical localization of leucokinin immunoreactivity in the brain of the cockroach Nauphoeta cinerea revealed neurosecretory cells in the pars intercerebralis and pars lateralis, several bilateral pairs of interneurons in the protocerebrum, and a group of interneurons in the optic lobe. Several immunoreactive interneurons were found in the thoracic ganglia, while the abdominal ganglia contained prominent immunoreactive neurosecretory cells, which projected to the lateral cardiac nerve. The presence of leucokinins in the abdominal nerve cord was confirmed by HPLC combined with ELISA. Leucokinin-immunoreactive neurosecretory cells were also found in the pars intercerebralis of the cricket Acheta domesticus and the mosquito Aedes aegypti, but not in the locust Schistocerca americana or the honey bee Apis mellifera. However, all these species have leucokinin-immunoreactive neurosecretory cells in the abdominal ganglia. The neurohemal organs innervated by abdominal leucokinin-immunoreactive cells were different in each species.
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    URL: http://dx.doi.org/10.1007/BF00354786
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    Possible multiple evolution of indirect telencephalo-cerebellar pathways in teleosts: studies in Carassius auratus and Pantodon buchholzi (1993)
    Springer
    Cell & tissue research 274 (1993), S. 447-455 
    Details
    ISSN: 1432-0878
    Keywords: Cerebellum ; Evolution ; Brain, vertebrate ; Pons ; Telencephalon ; Carassius auratus, Pantodon buchholzi (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Among vertebrates, telencephalo-pontine systems exist only in birds and mammals. However, three nuclei in the diencephalon and mesencephalon of teleost fishes have been indicated — analogous to the pons — to represent relay stations between telencephalon and cerebellum. Since two of these nuclei (dorsal preglomerular nucleus, dorsal tegmental nucleus) have only been described in the highly derived, electrosensory mormyrids, we investigated telencephalic connections in two nonelectrosensory teleosts, the goldfish Carassius auratus and the freshwater butterflyfish Pantodon buchholzi, and cerebellar connections only in the latter species, since for C. auratus these connections are already established. Horseradish peroxidase tracing reveals that C. auratus has a dorsal tegmental nucleus and a paracommissural nucleus both of which are telencephalo-recipient and project to the cerebellum, and that P. buchholzi has a dorsal preglomerular nucleus with such connections. These results extend our knowlegde of the distribution and, therefore, the phylogeny of telencephalo-cerebellar systems in teleosts. Similar to tetrapods, teleosts appear to have developed telencephalo-cerebellar systems several times independently.
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    Ultrastructural examination of the insemination reaction in Drosophila (1994)
    Springer
    Cell & tissue research 275 (1994), S. 467-479 
    Details
    ISSN: 1432-0878
    Keywords: Vagina ; Insemination reaction ; Postmating behavior ; Evolution ; Sperm competition ; Sexual selection ; Paragonia ; Drosophila (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The insemination reaction is a swelling of the female vagina caused by the male ejaculate. This postmating phenomenon is common among species in the genus Drosophila. It could act as a plug securing male paternity. It is not clear, however, what benefits it provides to the female. The structure formed in the female vagina is expelled in some species and disappears gradually in others suggesting different phenomena. Based on ultrastructural examination of the vaginal contents of five Drosophila species (D. mettleri, D. nigrospiracula, D. melanogaster, D. mojavensis, and D. hexastigma), we propose three terms to describe these vaginal structures: the sperm sac, the mating plug, and the true insemination reaction. Each term describes a distinct structure associated with a specific female postmating behavior. This study questions the concept of the insemination reaction as a single phenomenon and discusses its possible functions from an evolutionary perspective.
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    URL: http://dx.doi.org/10.1007/BF00318816
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    An immunocytochemical study of endocrine pancreas of snakes (1984)
    Springer
    Cell & tissue research 235 (1984), S. 657-661 
    Details
    ISSN: 1432-0878
    Keywords: Evolution ; Endocrine pancreas ; Regulatory peptides ; Snakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pancreas from eleven species of snakes representing both advanced and primitive families has been investigated for the presence of eleven regulatory peptides reported to occur in the mammalian endocrine pancreas. Of the eleven peptides studied, insulin, pancreatic glucagon and somatostatin were present in endocrine cells within the islets of all the species investigated. The neuropeptide, vasoactive intestinal polypeptide, was located within nerve terminals innervating the islets in the Boidinae, Colubrinae, Elaphidae and Crotalidae but absent from the Natricinae investigated. No immunoreactivity was demonstrable with the antisera to substance P, met-enkephalin, C-terminal gastrin, bombesin, glicentin and gastric inhibitory polypeptide. Pancreatic polypeptide-like immunoreactivity was demonstrable only in the boid snakes and exclusively stained by a C-terminal specific antiserum.
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    The parcellation theory and its relation to interspecific variability in brain organization, evolutionary and ontogenetic development, and neuronal plasticity (1980)
    Springer
    Cell & tissue research 213 (1980), S. 179-212 
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    ISSN: 1432-0878
    Keywords: Neocortex ; Evolution ; Development ; Plasticity ; Visual system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Recently discovered neocortical equivalents in anamniotes and certain patterns of interspecific variability in brain organization provide new insights into evolutionary and ontogenetic mechanisms of development. The new data suggest that nervous systems become more complex, not by one system invading another, but by a process of parcellation that involves the selective loss of connections of the newly formed daughter aggregates and subsystems. The parcellation process is reflected in the normal ontogenetic development of the CNS in a given species and can be manipulated, to a certain extent, by deprivation or surgically induced sprouting. The parcellation theory allows certain predictions about the range of variation of a given system at all levels of analysis including the cellular and aggregate levels. For example, the interspecific variability in organization of cortical columns, thalamic nuclei, cortical areas and tectal layers can be explained. The findings, summarized here, suggest that diffuse, undifferentiated systems existed in the beginning of vertebrate evolution and that during the evolution of complex behaviors, and analytical capacities related to these behaviors, a range of patterns of neural systems evolved that relate to these functions. One principle underlying the growth, differentiation and multiplication of neural systems appears to be the process of parcellation as defined by the theory.
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    Morphology and the evolution of cycadeoidales (1994)
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    Journal of plant research 107 (1994), S. 479-492 
    Details
    ISSN: 1618-0860
    Keywords: Cycadeoidales ; Evolution ; Gymnosperms ; Medullosales ; Morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract OneCycadeoidea stem one cycadeoidalean gynoecium and a bisporangiate cone attached to a slender cycadeoidalean trunkCycadeoidella japonica Ogura from the Cretaceous of Japan shows well-preserved internal structure that provides evidence for a better understanding of the morphological architecture of the cycadeoidalean plant. Structural details of the cone were confirmed. The ovule has an intergument enclosing a free nucellus and a thin outer envelope. Both reproductive and vegetative structures support the medullosan affinity of Cycadeoidales. The cone is interpreted as a compressed fertile shoot. Axillary cones characterizing some Cretaceous genera such asCycadeoidea andMonanthesia consist of a lateral shoot subtended by a frond that is the first leaf of the cone shoot itself. The origin of axillary buds in the Cycadeoidales is discussed. Heterochrony may have mediated the morphological changes that resulted in the establishment of the Cycadeoidales.
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    The six genes of the Rubisco small subunit multigene family from Mesembryanthemum crystallinum, a facultative CAM plant (1993)
    Springer
    Molecular genetics and genomics 239 (1993), S. 450-462 
    Details
    ISSN: 1617-4623
    Keywords: Rubisco small subunit ; Multigene family ; DNA sequence ; Gene conversion ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nucleotide sequences of the entire gene family, comprising six genes, that encodes the Rubisco small subunit (rbcS) multigene family in Mesembryanthemum crystallinum (common ice plant), were determined. Five of the genes are arranged in a tandem array spanning 20 kb, while the sixth gene is not closely linked to this array. The mature small subunit coding regions are highly conserved and encode four distinct polypeptides of equal lengths with up to five amino acid differences distinguishing individual genes. The transit peptide coding regions are more divergent in both amino acid sequence and length, encoding five distinct peptide sequences that range from 55 to 61 amino acids in length. Each of the genes has two introns located at conserved sites within the mature peptide-coding regions. The first introns are diverse in sequence and length ranging from 122 by to 1092 bp. Five of the six second introns are highly conserved in sequence and length. Two genes, rbcS-4 and rbcS-5, are identical at the nucleotide level starting from 121 by upstream of the ATG initiation codon to 9 by downstream of the stop codon including the sequences of both introns, indicating recent gene duplication and/or gene conversion. Functionally important regulatory elements identified in rbcS promoters of other species are absent from the upstream regions of all but one of the ice plant rbcS genes. Relative expression levels were determined for the rbcS genes and indicate that they are differentially expressed in leaves.
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    Comparison of the nucleotide sequences of the meta-cleavage pathway genes of TOL plasmid pWW0 from Pseudomonas putida with other meta-cleavage genes suggests that both single and multiple nucleotide substitutions contribute to enzyme evolution (1993)
    Springer
    Molecular genetics and genomics 239 (1993), S. 81-89 
    Details
    ISSN: 1617-4623
    Keywords: TOL plasmid ; Biodegradation ; Pseudornonas putida ; Evolution ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TOL plasmid pWW0 from Pseudomonas putida mt-2 encodes catabolic enzymes required for the oxidation of toluene and xylenes. The structural genes for these catabolic enzymes are clustered into two operons, the xylCMABN operon, which encodes a set of enzymes required for the transformation of toluene/xylenes to benzoate/toluates, and the xylXYZLTEGFJQKIH operon, which encodes a set of enzymes required for the transformation of benzoate/toluates to Krebs cycle intermediates. The latter operon can be divided physically and functionally into two parts, the xylXYZL cluster, which is involved in the transformation of benzoate/toluates to (methyl)catechols, and the xylTEGFJQKIH cluster, which is involved in the transformation of (methyl)catechols to Krebs cycle intermediates. Genes isofunctional to xylXYZL are present in Acinetobacter calcoaceticus, and constitute a benzoate-degradative pathway, while xylTEGFJQKIH homologous encoding enzymes of a methylphenol-degradative pathway and a naphthalene-degradative pathway are present on plasmid pVI150 from P. putida CF600, and on plasmid NAH7 from P. putida PpG7, respectively. Comparison of the nucleotide sequences of the xylXYZLTEGFJQKIH genes with other isofunctional genes suggested that the xylTEGFJQKIH genes on the TOL plasmid diverged from these homologues 20 to 50 million years ago, while the xylXYZL genes diverged from the A. calcoaceticus homologues 100 to 200 million years ago. In codons where amino acids are not conserved, the substitution rate in the third base was higher than that in synonymous codons. This result was interpreted as indicating that both single and multiple nucleotide substitutions contributed to the amino acid-substituting mutations, and hence to enzyme evolution. This observation seems to be general because mammalian globin genes exhibit the same tendency.
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    The use of the central raphe endings as a taxonomic character (1982)
    Springer
    Plant systematics and evolution 141 (1982), S. 143-152 
    Details
    ISSN: 1615-6110
    Keywords: Bacillariophyta ; Bacillariaceae ; Nitzschia ; Raphe Structure ; Systematics ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The use of the central raphe endings as a key character in the classification ofNitzschia is argued to be of doubtful validity. Some aspects of the evolution of the raphe are discussed in relation to variation in raphe structure within fibulate genera.
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    Inferred chromosome morphology of the ancestral genome ofTriticum (1984)
    Springer
    Plant systematics and evolution 144 (1984), S. 209-220 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Poaceae ; Triticum ; Elytrigia ; wheat ; Evolution ; genome ; karyotype
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The lengths of the A, B, and D genomes of common wheat,Triticum aestivum, were measured from the karyotype. Relative to the B genome, standardized as length 1.000, the lengths of the A and D genomes were 0.835 and 0.722, respectively. The lengths of the chromosome arms in the A and D genomes were then multiplied by the appropriate constants so that the total lengths of each genome also equalled 1.000. These calculations revealed that homoeologous chromosomes in wheat, with a few exceptions, have similar sizes and arm ratios. The arm lengths of the three homoeologues in each homoeologous group were then averaged. These average chromosomes turned out to be remarkably similar, in size and arm ratio, to their homoeologues in the E genome ofElytrigia elongata. This evidence and data on cross-compatibility and morphological characteristics suggested that the genusTriticum is a result of adaptive radiation from the perennial genusElytrigia, specifically from the complex of species possessing the E genome or one closely related to it.
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    Karyotypic evolution, morphological variability and phylogeny inMedicago sect.Intertextae (1984)
    Springer
    Plant systematics and evolution 145 (1984), S. 203-222 
    Details
    ISSN: 1615-6110
    Keywords: Fabaceae ; Leguminosae ; Medicago ciliaris ; Medicago intertexta ; Medicago muricoleptis ; Medicago granadensis ; Evolution ; chromosomes ; Pleistocene glaciations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Karyotype and external morphological analyses were conducted onMedicago ciliaris, M. intertexta, M. muricoleptis andM. granadensis which comprise theIntertextae section of the genusMedicago. All species were found to have 2n = 16 chromosomes (= 2 ×), including one pair of satellite chromosomes in each respective complement. Karyotypic evolution in theIntertextae involves changes in absolute chromosome size and in centromeric and relative size symmetry. Numerical taxonomic analyses were conducted independently on 17 karyotypic features and on 16 features of external morphology. The results of the two sets of analyses proved comparable, withM. ciliaris andM. intertexta forming a fairly close pair, and the remaining two species appearing to have more distant relationships to each other and to the first pair. These observations are consistent with the infertility relationships and chorologies of the species. It is suggested thatM. muricoleptis andM. granadensis are derived from theM. ciliaris/intertexta species complex withM. granadensis arising fromM. muricoleptis, or these two species independently evolving from a common species complex. Chromosomal and numerical analyses suggest thatM. ciliaris is the most primitive andM. granadensis the most derived species of theIntertextae.
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    Association of the plant p34cdc2-like protein with p13suc1: implications for control of cell division cycles in plants (1991)
    Springer
    Protoplasma 161 (1991), S. 70-74 
    Details
    ISSN: 1615-6102
    Keywords: Cell division cycle ; Wheat ; cdc2 ; suc1 ; Protein kinase ; H1 histone kinase ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Thecdc2-like p34 protein of wheat is closely similar to the p34cdc2 enzyme of yeasts and animals since both have binding affinity for p13suc1 protein encoded by the fission yeastsuc1 gene. In yeast p13suc1 participates in modulation of p34cdc2 activity and is necessary for completion of mitosis. Wheat p34 that was affinity purified on p13suc1 contained the PSTAIR amino acid sequence that is present in all known p34cdc2 homologues and it also had H1 histone protein kinase activity that was independent of calcium and cyclic AMP, which is characteristic of p34cdc2 in vitro. Functional equivalence with the known cell cycle control protein supports our earlier proposition that the high level of this homologue in wheat leaf meristem is important in determining where cell division can occur and the capacity for resumption of cell division. The affinity of plant p34 for fission yeast p13suc1 suggested that a similar association occurs in plants. We have detected a plant homologue of pl3suc1 using affinity-purified antibody raised against the fission yeast protein, in wheat, pea andChlamydomonas. We conclude that the distribution of p13suc1 homologue in plants is likely to be ubiquitous. Thesuc1 gene function inSchizosaccharomyces pombe is essential for mitosis, in which it is required for inactivation of p34cdc2. We propose that association of plant p34 with p13suc1 is similarly involved in plant mitosis.
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    A light and electron microscopic study of stigmas inAneilema andCommelina species (Commelinaceae) (1982)
    Springer
    Protoplasma 112 (1982), S. 26-36 
    Details
    ISSN: 1615-6102
    Keywords: Aneilema ; Commelina ; Cytochemistry ; Evolution ; Papillae ; Pollination ; Secretion ; Stigmas ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The stigmas of species inAneilema andCommelina are trifid and comprise elongate papillae. Progressive degeneration of papular cells is observed in stigmas from open flowers and at anthesis papillae may be moribund and collapsed. Fluid emanating from the hollow style flows onto the surface through ruptures in the cuticle at the interpapillar junctions into the interstices at maturity. This secretion stains positively for protein. Stigmas are of the “wet” type. The cuticle overlying the papillar cells is ridged and at the final stages prior to flowering this cuticle becomes detached from the underlying cellulosic wall. The sub-cuticular space so formed is filled with secretion. InAneilema species detachment of cuticle is at the papillar tip and along the lateral walls. InCommelina species the anticlinal walls of adjacent papillae are strongly attached for much of their length and thus detachment of cuticle is restricted to the papillar tip. The cell wall at the tip in both genera may proliferate forming a rudimentary transfer-cell type wall. The secretion is considered to be produced by the papillar cells. It is PAS positive but fails to stain for protein and in both the light and electron microscopes appears heterogenous. Pollen attachment, hydration, germination and early tube growth are very rapid following self-pollination, the pollen tubes entering the neck of the style within ten minutes of attachment. A unique character combination involving pollen and stigmas in these genera indicates a monophyletic origin.
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    A monoclonal antibody to animal centrosomes recognizes components of the basal-body root complex inChlamydomonas (1990)
    Springer
    Protoplasma 153 (1990), S. 208-211 
    Details
    ISSN: 1615-6102
    Keywords: Basal-body root complex ; Cell division cycle ; Centrosome ; Chlamydomonas ; Evolution ; Monoclonal antibody
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mammalian centrosome monoclonal antibody MPM-13 recognized component(s) of the well defined MTOC basal-body root complex in the green plantChlamydomonas. The antibody reaction coincided in location with the basal-body root complex and the cruciate nature of the staining pattern corresponded to the configuration of the root microtubules. During mitosis the behaviour of MPM-13 stained material mirrored the duplication, separation and migration to the spindle poles of the basal body-root complex. It is suggested that conserved MTOC components were recognized and that these may have retained a similar, perhaps universal, function in microtubule organization.
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    Volvocine cell walls and their constituent glycoproteins: An evolutionary perspective (1994)
    Springer
    Protoplasma 181 (1994), S. 245-258 
    Details
    ISSN: 1615-6102
    Keywords: Evolution ; Hydroxyproline-rich glycoprotein ; Cell wall ; Phylogenetics ; Chlamydomonas ; Volvocales
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Similarities in the composition of the extracellular matrix suggest that only some species of the unicellularChlamydomonas are closely related to the colonial and multicellular flagellated members of the family Volvocaceae. The cell walls from all of the algae in this volvocine group contain a crystalline layer. This lattice structure can be used as a phylogenetic marker to divideChlamydomonas species into distinct classes, only one of which includes the volvocacean algae. Similarly, not all species ofChlamydomonas are sensitive to each other's cell wall lytic enzymes, implying divergence of the enzyme's inner wall substrate. Interspecific reconstitution of the crystalline layer is possible betweenC. reinhardtii and the multicellularVolvox carteri, but not betweenC. reinhardtii andC. eugametos. The hydroxyproline-rich glycoproteins (HRGPs) which make up the crystalline layer in genera which have a similar crystal structure exhibit many homologies. Interestingly, the evolutionarily distant cell walls ofC. reinhardtii andC. eugametos also contain some HRGPs displaying a few morphological and amino acid sequence homologies. The morphological similarities between the flagellar agglutinins (HRGPs responsible for sexual recognition and adhesion during the mating reaction) and the cell wall HRGPs leads to the proposal of a superfamily from which novel HRGPs (designed for self-assembly/recognition) can constantly evolve. Just as variations in the wall HRGPs can lead to unique wall structures, new agglutinins facilitate sexual isolation of new species. Thus, the HRGPs could emerge as valuable phylogenetic markers.
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    High-speed video analysis of the flagellar beat and swimming patterns of algae: possible evolutionary trends in green algae (1991)
    Springer
    Protoplasma 164 (1991), S. 54-69 
    Details
    ISSN: 1615-6102
    Keywords: Green algae ; Flagellar beat ; Video analysis ; Evolution ; Swimming patterns ; Prasinophyceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The flagellar beat and swimming patterns of flagellated cells of 22 green plants, including 17 green flagellates (volvocalean and prasinophyte algae), motile cells of three seaweeds,Bryopsis, Caulerpa, andUlva, sperms of a liverwort,Marchantia, and a fern,Athyrium, were examined using a high-speed video system. So-called breast-stroke is widely distributed in green plants, and occurs rarely in prasinophyte flagellates and ulvophycean algae; in these algal groups flagellar beat similar to that found in animal sperm is common, both during forward and backward swimming. Different types of swimming patterns were observed in prasinophytes. The results indicate evolutionary trends of flagellar beat and swimming patterns in green plants such as change from backward to forward swimming, from flagellar to ciliary beating and from uni-directional (parallel) to radial-directional (cruciate) beating. Such trends are shown in two prasinophyte groups, thePyramimonas-lineage andTetraselmis-lineage.
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    The semantic approach to evolutionary theory (1991)
    Springer
    Biology and philosophy 6 (1991), S. 59-80 
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    ISSN: 1572-8404
    Keywords: Evolution ; semantic approach ; theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract Paul Thompson, John Beatty, and Elisabeth Lloyd argue that attempts to resolve certain conceptual issues within evolutionary biology have failed because of a general adherence to the received view of scientific theories. They maintain that such issues can be clarified and resolved when one adopts a semantic approach to theories. In this paper, I argue that such conceptual issues are just as problematic on a semantic approach. Such issues arise from the complexity involved in providing formal accounts of theoretical laws and scientific explanations. That complexity is due to empirical and pragmatic considerations, not one's adherence to a particular formal approach to theories. This analysis raises a broader question. How can any formal account properly represent the complex nature of empirical phenomena?
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    What is this stuff called fitness? (1991)
    Springer
    Biology and philosophy 6 (1991), S. 81-92 
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    ISSN: 1572-8404
    Keywords: Evolution ; fitness ; natural selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract This paper considers a variety of attempts to define fitness in such a way as to defend the theory of evolution by natural selection from the criticism that it is a circular argument. Each of the definitions is shown to be inconsistent with the others. The paper argues that the environment in which an animal evolves can be defined only with respect to the properties of the phenotype of the animal and that it is therefore not illuminating to try to explain the phenotypic properties of the animal in terms of adaptation to an environment that is defined by those very properties. Furthermore, since there is no way that the environment can be defined independently of the presence of the animal there is no way that the quality of an animal can be assessed; and there can be no objective criteria by whichany form of selection can be carried out, therefore there can be no criteria by whichnatural selection can be carried out. It is proposed that fitness is nothing more than the production of offspring, that this is a phenotypic property like all the others, and if it is heritable then the offspring of the parents that produce the most offspring will themselves produce the most offspring, and that in principle it is impossible to account for this in terms of the other phenotypic properties of the fittest animals except by circular argument. Differential rates of reproduction are the causes of evolution and the phenotypic causes are strictly inexplicable.
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    URL: http://dx.doi.org/10.1007/BF02426827
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    Science and selection (1994)
    Springer
    Biology and philosophy 9 (1994), S. 45-62 
    Details
    ISSN: 1572-8404
    Keywords: Evolution ; evolutionary epistemology ; Hull ; interactor ; progress ; replicator ; selection theory ; vehicle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract In this paper I consider the view that scientific change is the result of a selection process which has the same structure as that which drives natural selection. I argue that there are important differences between organic evolution and scientific growth. First, natural selection is much more constrained than scientific change; for example it is hard to populations of organisms to escape local maxima. Science progresses; it may not even make sense to say that biological evolution is progressive. Second, natural selection depends for its power on the specifics of its domain, so I doubt that there is much point in seeing a selective regime in science as an instance of a more general family of selective regimes. Third, the replicator/interactor distinction fits scientific change much less well than biological evolution. But a family of selective theories of science can be identified ranging from the very ambitious to the very modest. Though the very ambitious programs of evolutionary epistemology are in trouble, there is space for one which is not a trivial redescription of what everyone already knows, but which is sensitive to the peculiarities of its domain. That selective theory explains important aspects of the community organization of science, an organization which is central to scientific progress.
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    URL: http://dx.doi.org/10.1007/BF00849913
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    Centres of speciation and ecological differentiation in the Galapagos land bird fauna (1990)
    Springer
    Evolutionary ecology 4 (1990), S. 130-142 
    Details
    ISSN: 1573-8477
    Keywords: Evolution ; Darwin's finches ; extinction ; Geospizinae ; island biogeography ; ecological isolation ; reproductive isolation ; speciation ; taxon cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Hamilton-Rubinoff model of evolution in the avifauna of the Galapagos Islands suggests that speciation occurs on small outlying islands, and that new species invade the central island region, where ecological differentiation takes place. I present an alternative model in which both speciation and ecological differentiation leading to origin of actively colonizing taxa occur on the large islands, with colonization of small and outlying islands being primarily one way. Although forms on outlying islands may differentiate to the level of new species, their fate is postulated to be extinction rather than re-invasion of central islands. Data on species with expanding, differentiating, fragmenting, and relict distributions support this second model. Polytypy and incompleteness of distributions on the large islands indicate that isolation is adequate for differentiation to occur. Distributions of expanding taxa centre on the large islands, and their distributions show sequences leading from large islands to smaller and more outlying islands. Curves of occupancy of large islands versus total islands also agree with the prediction that expansions begin in the large islands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02270910
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    Protein variation, taxonomy and differentiation in five species of marmosets (genusCallithrix Erxleben, 1777) (1992)
    Springer
    Primates 33 (1992), S. 227-238 
    Details
    ISSN: 0032-8332
    Keywords: Callithrix ; Heterozygosity ; Biochemical markers ; Taxonomy ; Polymorphism ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The electrophoretic patterns of 15 protein systems codified for 20 genetic loci were investigated using horizontal electrophoresis. A total of 150 blood samples, from five species of the genusCallithrix were analyzed. Polymorphic variation was observed in 10 out 20 loci analyzed. The genotypic distributions are in Hardy-Weinberg equilibrium. The average heterozygosity (H) varied from 1% to 5%, similar to those observed for other Neotropical primates. The genetic distance coefficients revealed a phylogenetic separation of these species into two groups: (1) “argentata” (C. humeralifer andC. emiliae); (2) “jacchus” (C. jacchus, C. penicillata, andC. geoffroyi). This arrangement is according to the taxonomic arrangement proposed byHershkovitz (1977),de Vivo (1988), andMittermeier et al. (1988). The results in each group are compatible with the subspecies values recorded for the Platyrrhini. These values showed that:C. humeralifer andC. emiliae are subspecies ofC. argentata;C. jacchus, C. penicillata, andC. geoffroyi are subspecies ofC. jacchus. These results also suggest thatC. j. geoffroyi is the “jacchus” group taxon, most similar genetically to the “argentata” group.
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    URL: http://dx.doi.org/10.1007/BF02382752
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  • 193
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    Anatomy and evolution in MacaronesianEchium (Boraginaceae) (1981)
    Springer
    Plant systematics and evolution 138 (1981), S. 9-22 
    Details
    ISSN: 1615-6110
    Keywords: Boraginaceae ; Echium ; Evolution ; anatomy ; paedomorphosis ; pachycauls ; tracheary elements ; wood rays ; stem anatomy ; Macaronesian flora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The endemic Macaronesian members of the genusEchium (Boraginaceae) were examined anatomically to elucidate their relationships. Vessel length to breadth ratio was used as the initial guide to the relative primitive or derived nature of each taxon. Together with other features (e.g. trichome structure) it was possible to establish the phylogenetic pathways within this recently evolved relict group (Fig. 1).
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    URL: http://dx.doi.org/10.1007/BF00984605
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    Analysis of expression and evolutionary relationships of phosphoenol-pyruvate carboxylase genes in Flaveria trinervia (C4) and F. pringlei (C3) (1990)
    Springer
    Molecular genetics and genomics 224 (1990), S. 459-468 
    Details
    ISSN: 1617-4623
    Keywords: Flaveria ; C3/C4 plants ; Phosphoenolpyruvate carboxylase ; Gene family ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Phosphoenolpyruvate carboxylase (PEPCase) was shown to be encoded by a multigene family in various Flaveria species analysed. Several clones were isolated from genomic libraries of F. pringlei (C3 species) and F. trinervia (C4 species) and classified into four distinct groups according to their hybridization behaviour to a full-length cDNA clone encoding the PEPCase C4 isozyme of F. trinervia. A detailed cross-hybridization analysis demonstrated that the closest relative of most of the PEPCase genes isolated from F. trinervia and F. pringlei was not found in the same but in the other species. Northern analysis, using stringent conditions, allowed discrimination of class-specific PEPCase transcripts and revealed characteristic organ-specific expression patterns.
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    URL: http://dx.doi.org/10.1007/BF00262441
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    A mutation affecting amdS expression in Aspergillus nidulans contains a triplication of a cis-acting regulatory sequence (1990)
    Springer
    Molecular genetics and genomics 220 (1990), S. 373-376 
    Details
    ISSN: 1617-4623
    Keywords: Aspergillus nidulans ; Gene regulation ; amdS gene ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Aspergillus nidulans expression of the acetamidase structural gene, amdS, is under the control of at least four regulatory genes including the trans-acting amdA regulatory gene. A cis-acting mutation (amdI66) consisting of an 18 by duplication in the 5′ region of the amdS gene results in very high levels of acetamidase activity but only in strains carrying semi-dominant mutations in the amdA gene. In selecting for increased amdS expression in an amdI66 amdA – strain, an A. nidulans strain with a mutation in the 5′ region of the amdS gene was isolated. The nucleotide sequence was determined of the region containing the mutation, designated amdI666. The mutant strain carries three tandem copies of the 18 by sequence that is duplicated in the amdI66 mutation. Thus, from a strain carrying a duplication of an apparent regulatory protein binding site with little effect on gene expression, a strain has been derived that carries a triplication of the site with consequent major effects on regulation. The multiple copies of regulatory sites present in many genes may have been generated by a similar mechanism.
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    URL: http://dx.doi.org/10.1007/BF00391741
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    Structure of the archaebacterial 7S RNA molecule (1990)
    Springer
    Molecular genetics and genomics 221 (1990), S. 315-321 
    Details
    ISSN: 1617-4623
    Keywords: Small stable RNA ; Signal recognition particle ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genes encoding the 7S RNAs of the archaebacteria Archaeoglobus fulgidus, Methanosarcina acetivorans, Sulfolobus solfataricus, and Thermococcus celer have been isolated. All four genes occur as single genomic copies and are flanked by sequences containing potential signals for transcriptional promotion and termination. The genes encode RNA molecules approximately 300 nucleotides in length which conform strictly to a model of secondary structure common to all described archaebacterial 7S RNAs. Archaebacterial 7S RNAs exhibit a strong similarity to eukaryotic 7S RNAs in terms of overall secondary structure, while primary sequence conservation is limited to a specific structural domain of the molecule. This domain displays strong primary and secondary structural similarity to features of small eubacterial RNAs, including the small cytoplasmic (sc) RNA of Bacillus subtilis and the 4.5S RNA of Escherichia coli. Conservation of this structural domain among divergent RNA molecules across three kingdoms suggests that these RNAs are the descendants of a unique subcellular structure present before the divergence of the archaebacterial, eubacterial and eukaryotic kingdoms.
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    URL: http://dx.doi.org/10.1007/BF00259394
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    Widespread occurrence of the Tc1 transposon family: Tc1-like transposons from teleost fish (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 606-612 
    Details
    ISSN: 1617-4623
    Keywords: Evolution ; Vertical transmission ; Phylogenetic relationships ; Transposable element Transposase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We characterized five transposable elements from fish: one from zebrafish (Brachydanio rerio), one from rainbow trout (Salmo gairdneri), and three from Atlantic salmon (Salmo salar). All are closely similar in structure to the Tel transposon of the nematode Caenorhabditis elegans. A comparison of 17 Tc1-like transposons from species representing three phyla (nematodes, arthropods, and chordates) showed that these elements make up a highly conserved transposon family. Most are close to 1.7 kb in length, have inverted terminal repeats, have conserved terminal nucleotides, and each contains a single gene encoding similar poly peptides. The phylogenetic relationships of the transposons were reconstructed from the amino acid sequences of the conceptual proteins and from DNA sequences. The elements are highly diverged and have evidently inhabited the genomes of these diverse species for a long time. To account for the data, it is not necessary to invoke recent horizontal transmission.
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    URL: http://dx.doi.org/10.1007/BF00282750
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    An Arabidopsis gene homologous to mammalian and insect genes encoding the largest proteasome subunit (1993)
    Springer
    Molecular genetics and genomics 241 (1993), S. 586-594 
    Details
    ISSN: 1617-4623
    Keywords: Proteasome ; Arabidopsis ; Deletion mutation ; Gene expression ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A gene encoding a protein with extensive homology to the largest subunit of the multicatalytic proteinase complex (proteasome) has been identified in Arabidopsis thaliana. This gene, referred to as AtPSM30, is entirely encompassed within a previously characterized radiation-induced deletion, which may thus provide the first example of a proteasome null mutation in a higher eukaryote. However, the growth rate and fertility of Arabidopsis plants do not appear to be significantly affected by this mutation, even though disruption experiments in yeast have shown that most proteasome subunits are essential. Analysis of mRNA levels in developing seedlings and mature plants indicates that expression of AtPSM30 is differentially regulated during development and is slightly induced in response to stress, as has been observed for proteasome genes in yeast, Drosophila, and mammals. Southern blot analysis indicates that the Arabidopsis genome contains numerous sequences closely related to AtPSM30, consistent with recent reports of at least two other proteasome genes in Arabidopsis. A comparison of the deduced amino acid sequences for all proteasome genes reported to date suggests that multiple proteasome subunits evolved in eukaryotes prior to the divergence of plants and animals.
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    URL: http://dx.doi.org/10.1007/BF00279901
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    Medicago truncatula f.laxicycla (Leguminosae), a new taxon with loose fruit coiling promoting rapid germination of the fruit-retained seeds (1991)
    Springer
    Plant systematics and evolution 174 (1991), S. 37-46 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Leguminosae ; Medicago truncatula f.laxicycla ; M. laxispira ; Evolution ; adaptation ; seed germination ; chromosome number ; Flora of Libya
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Medicago truncatula is a member ofMedicago sect.Spirocarpos, in which all 34 species have coiled fruit, usually tightly coiled, that permanently retain the seeds. A variant ofM. truncatula from Libya is unique for the species in possessing very loosely coiled fruits, and is here recognized as a new forma,M. truncatula f.laxicycla E. Small. In germination tests of a number of species ofMedicago, the unusual Libyan variant proved to be the only one in which rapid and simultaneous germination of most of the seeds occurred while still within a fruit. The loose coiling of the fruit of the Libyan variety appears to facilitate water entry and seedling escape. Its rapid germination might adapt it to respond quickly to intermittently available moisture, but at the cost of abandoning the strategy of intermittent germination adopted by other populations ofMedicago sect.Spirocarpos.
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    URL: http://dx.doi.org/10.1007/BF00937692
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    Chloroplast DNA variation and the phylogeny ofAsplenium sect.Hymenasplenium (Aspleniaceae) in the New World tropics (1994)
    Springer
    Journal of plant research 107 (1994), S. 245-251 
    Details
    ISSN: 1618-0860
    Keywords: Aspleniaceae ; Asplenium sect.Hymenasplenium ; Chloroplast DNA ; Evolution ; Molecular phylogeny ; New World tropics ; Restriction site variation analyses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Asplenium sect.Hymenasplenium is a well-defined group in Aspleniaceae, distinguished by several morphological and cytological characters. However, interspecific relationships in the section were not clear. In this paper, we report the phylogenetic relationships of 9 Neotropical species of sect.Hymenasplenium determined by chloroplast DNA restriction site variation analyses. From the obtained phylogenetic tree, two major clades: one withA. obtusifolium, A. riparium, A. volubile andA. repandulum and another withA. delitescens, A. ortegae, A. purpurascens, A. laetum andA. hoffmannii were recognized.Asplenium delitescens was shown to have a polyphyletic origin. It was also shown that the epiphytic habit evolved only once in the New World species of sect.Hymenasplenium.
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    URL: http://dx.doi.org/10.1007/BF02344251
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