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  • Evolution
  • Springer  (67)
  • Frontiers Media SA
  • 1980-1984  (67)
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  • 1
    Digitale Medien
    Digitale Medien
    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 
    Details
    ISSN: 1432-1416
    Schlagwort(e): Evolution ; quantitative inheritance ; random matrix theory ; morphological integration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: 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).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00275224
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  • 2
    Digitale Medien
    Digitale Medien
    A model of evolutionary appearance of dissipative structure in ecosystems (1983)
    Springer
    Journal of mathematical biology 18 (1983), S. 13-23 
    Details
    ISSN: 1432-1416
    Schlagwort(e): Ecosystem ; Evolution ; Autonomous oscillations ; issipative structure ; Bifurcation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: 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).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00275907
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  • 3
    Digitale Medien
    Digitale Medien
    A mathematical model of biological evolution (1982)
    Springer
    Journal of mathematical biology 14 (1982), S. 327-353 
    Details
    ISSN: 1432-1416
    Schlagwort(e): Evolution ; Molecular evolution ; Dynamical system ; Neo-Darwinian evolution ; Non-Darwinian evolution ; Neutral theory
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00275397
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  • 4
    Digitale Medien
    Digitale Medien
    Evolutionary stable strategies and game dynamics for n-person games (1984)
    Springer
    Journal of mathematical biology 19 (1984), S. 329-334 
    Details
    ISSN: 1432-1416
    Schlagwort(e): Evolution ; ESS ; games ; game dynamics ; n-person games ; strategies
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00277103
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  • 5
    Digitale Medien
    Digitale Medien
    Polymorphism with selection and genotype-dependent migration (1981)
    Springer
    Journal of mathematical biology 11 (1981), S. 245-267 
    Details
    ISSN: 1432-1416
    Schlagwort(e): Population genetics ; Evolution ; Migration ; Geographical variation ; Habitat choice ; Polymorphism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00276896
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  • 6
    Digitale Medien
    Digitale Medien
    Evolutionary analysis ofα andβ hemoglobin genes by reh theory under the assumption of the equiprobability of genetic events (1980)
    Springer
    Journal of molecular evolution 15 (1980), S. 149-159 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Genes ; REH theory ; Genetic distance ; Evolution ; mRNA ; Nucleic acids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary It is shown how REH theory in conjunction with mRNA or gene sequence data can be used to obtain estimates of the fixation intensity, the number of varions, and the total mutations fixed between homologous pairs of nucleic acids. These estimates are more accurate than those that can be derived from amino acid sequence data. The method is illustrated forα andβ hemoglobin genes and these improved estimates are compared with those made from the amino acid sequences for which those genes code. Significant differences are found between the estimates made by these two methods. For theβ hemoglobin gene sequences examined here, the fixation intensity is some-what less than the protein data had suggested, and the number of rations is considerably greater. Depending on the gene sequences examined, between 62 and 83% of the codons appear able to fix mutations during the divergences considered. This reflects the constraints of natural selection on acceptable mutations. The total number of base replacements separating the genes for human, mouse, and rabbitβ hemoglobin varies from 61 to 105 depending on the pair examined. Rabbitα andβ hemoglobin are separated by at least 290 fixed mutations. For such distantly related sequences estimates made from protein and mRNA data differ less, reflecting the higher quality of information from the many observed changes in primary structure. The effects of nonrandom gene structure on these evolutionary estimates and the fact that various genetic events are not equiprobable are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01732667
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  • 7
    Digitale Medien
    Digitale Medien
    The relationship between coding sequences and function in some heme binding proteins (1980)
    Springer
    Journal of molecular evolution 16 (1980), S. 149-150 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Exons ; Evolution ; Heme-binding proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary It is known that globin genes contain three exons with the middle exon coding for a four-helical supersecondary structure responsible for heme binding. Since this portion of the globin peptide chain can be structurally superimposed onto the cytochromec and cytochromeb 5 chains (Argos and Rossmann 1979), it can be inferred that the cytochromec gene will contain only one coding sequence while the cytochromeb 5 gene will be composed of three exons as found in the globin gene.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01731583
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  • 8
    Digitale Medien
    Digitale Medien
    Theoretical foundations for quantitative paleogenetics (1980)
    Springer
    Journal of molecular evolution 16 (1980), S. 211-267 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Nucleic acids ; Proteins ; Natural selection ; Genetics ; Nonrandom molecular divergence ; Nonrandom REH theory ; Evolution ; mRNA ; DNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary REH theory is extended by deriving the theoretical equations that permit one to analyze the nonrandom molecular divergence of homologous genes and proteins. The nonrandomicities considered are amino acid and base composition, the frequencies with which each of the four nucleotides is replaced by one of the other three, unequal usage of degenerate codons, distribution of fixed base replacements at the three nucleotide positions within codons, and distributions of fixed base replacements among codons. The latter two distributions turn out to dominate the accuracy of genetic distance estimates. The negative binomial density is used to allow for the unequal mutability of different codon sites, and the implications of its two limiting forms, the Poisson and geometric distributions, are considered. It is shown that the fixation intensity — the average number of base replacements per variable codon - is expressible as the simple product of two factors, the first describing the asymmetry of the distribution of base replacements over the gene and the second defining the ratio of the average probability that a codon will fix a mutation to the probability that it will not. Tables are given relating these features to experimentally observable quantities inα hemoglobin,β hemoglobin, myoglobin, cytochromec, and the parvalbumin group of proteins and to the structure of their corre-sponding genes or mRNAs. The principal results are (1) more accurate methods of estimating parameters of evolutionary interest from experimental gene and protein sequence data, and (2) the fact that change in gene and protein structure has been a much less efficient process than previously believed in the sense of requiring many more base replacements to effect a given structural change than earlier estimation procedures had indicated. This inefficiency is directly traceable to Darwinian selection for the nonrandom gene or protein structures necessary for biological function. The application of these methods is illustrated by detailed consideration of the rabbitα -andβ hemoglobin mRNAs and the proteins for which they code. It is found that these two genes are separated by about 425 fixed base replacements, which is a factor of two greater than earlier estimates. The replacements are distributed over approximately 114 codon sites that were free to accept base mutations during the divergence of these two genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01804977
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  • 9
    Digitale Medien
    Digitale Medien
    Ancient repeated sequences in the pea and mung bean genomes and implications for genome evolution (1981)
    Springer
    Journal of molecular evolution 17 (1981), S. 31-42 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Pea ; Mung bean ; Genome organization ; Evolution ; Amplification ; Repetitive DNA ; Single copy DNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Essentially all of the sequences in the pea (Pisum sativum) genome which reassociate with single copy kinetics at standard (Tm -25°C) criterion follow repetitive kinetics at lower temperatures (about Tm-35°C). Analysis of thermal stability profiles for presumptive single copy duplexes show that they contain substantial mismatch even when formed at standard criterion. Thus most of the sequences in the pea genome which are conventionally defined as “single copy” are actually “fossil repeats” — that is, they are members of extensively diverged (mutuated) and thus presumably ancient families of repeated sequences. Coding sequences as represented by a cDNA probe prepared from poly-somal poly(A) + mRNA reassociate with single copy kinetics regardless of criterion and do not form mismatched duplexes. The coding regions thus appear to be composed of true single copy sequences but they cannot represent more than a few percent of the pea genome. Ancient diverged repeats are present, but not a prominent feature of the smaller mung bean (Vigna radiata) genome. An extension of a simple evolutionary model is proposed in which these and other differences in genome organization are considered to reflect different rates of sequence amplification or genome turnover during evolution. The model accounts for some of the differences between typical plant and animal genomes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01792422
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  • 10
    Digitale Medien
    Digitale Medien
    The estimation of genetic divergence (1981)
    Springer
    Journal of molecular evolution 17 (1981), S. 167-181 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Genetics ; REH theory ; Mutations ; Natural selection ; Nucleic acids ; Proteins ; Paleogenetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have independently repeated the computer simulations on which Nei and Tateno (1978) base their criticism of REH theory and have extended the analysis to include mRNAs as well as proteins. The simulation data confirm the correctness of the REH method. The high average value of the fixation intensity μ2 found by Nei and Tateno is due to two factors: 1) they reported only the five replications in which μ2 was high, excluding the forty-five replications containing the more representative data;and 2) the lack of information, inherent to protein sequence data, about fixed mutations at the third nucleotide position within codons, as the values are lower when the estimate is made from the mRNAs that code for the proteins. REH values calculated from protein or nucleic acid data on the basis of the equiprobability of genetic events underestimate, not overestimate, the total fixed mutations. In REH theory the experimental data determine the estimate T2 of the time average number of codons that have been free to fix mutations during a given period of divergence. In the method of Nei and Tateno it is assumed, despite evidence to the contrary, that every amino acid position may fix a mutation. Under the latter assumption, the measure X2 of genetic divergence suggested by Nei and Tateno is not tenable: values of X2 for theα hemoglobin divergences are less than the minimum number of fixed substitutions known to have occurred. Within the context of REH theory, a paradox, first posed by Zuckerkandl, with respect to the high rate of covarion turnover and the nature of general function sites in proteins is resolved.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01733911
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  • 11
    Digitale Medien
    Digitale Medien
    Evolutionary trees from DNA sequences: A maximum likelihood approach (1981)
    Springer
    Journal of molecular evolution 17 (1981), S. 368-376 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Phylogeny ; Maximum likelihood ; Parsimony ; Estimation ; DNA sequences
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The application of maximum likelihood techniques to the estimation of evolutionary trees from nucleic acid sequence data is discussed. A computationally feasible method for finding such maximum likelihood estimates is developed, and a computer program is available. This method has advantages over the traditional parsimony algorithms, which can give misleading results if rates of evolution differ in different lineages. It also allows the testing of hypotheses about the constancy of evolutionary rates by likelihood ratio tests, and gives rough indication of the error of the estimate of the tree.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01734359
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  • 12
    Digitale Medien
    Digitale Medien
    Amino acid codes in mitochondria as possible clues to primitive codes (1981)
    Springer
    Journal of molecular evolution 18 (1981), S. 15-17 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Amino acid code ; Evolution ; Primitive codes ; Mitochondria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Differences between mitochondrial codes and the universal code indicate that an evolutionary simplification has taken place, rather than a return to a more primitive code. However, these differences make it evident that the universal code is not the only code possible, and therefore earlier codes may have differed markedly from the previous code. The present universal code is probably a “frozen accident.” The change in CUN codons from leucine to threonine (Neurospora vs. yeast mitochondria) indicates that neutral or near-neutral changes occurred in the corresponding proteins when this code change took place, caused presumably by a mutation in a tRNA gene.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01733206
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  • 13
    Digitale Medien
    Digitale Medien
    Studies on the evolutionary relationships between hemoglobins inChironomus pallidivittatus andC. Tentans (1981)
    Springer
    Journal of molecular evolution 18 (1981), S. 9-14 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Monomeric hemoglobins ; Dimeric hemoglobins ; Chironomus ; Antibodies ; Evolution ; Gene duplication
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The monomeric hemoglobins ofChironomus tentans andC. pallidivittatus have been isolated and separated into their respective components by gel chromatography on Sephadex G-75 and ion-exchange chromatography on DEAE-Sephacel. The amino acid compositions of the purified components are given. The sequence of the 30 N-terminal amino acid residues of one of the monomeric components (Hb I fromC. pallidivittatus) was determined and found to be identical in almost all of its parts with the monomeric hemoglobins ofC. thummi (CTT III and CTT IV). Antibodies against the monomeric hemoglobins Hb I and Hb IIc and the dimeric fraction were highly specific and no cross reaction between dimeric and monomeric hemoglobins could be demonstrated. The antibodies against the monomers crossreact with the monomeric hemoglobins CTT III and CTT IV ofC. thummi. Taken together with genetic data, the immunological results indicate that divergence of monomeric from dimeric forms was an early event in the evolution of the various hemoglobins inChironomus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01733205
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  • 14
    Digitale Medien
    Digitale Medien
    Taxonomic relations between archaebacteria including 6 novel genera examined by cross hybridization of DNAs and 16S rRNAs (1982)
    Springer
    Journal of molecular evolution 18 (1982), S. 109-114 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Archaebacteria ; Taxonomy ; Evolution ; DNA ; 16S rRNA ; Hybridization ; Phylogeny ; Thermoproteales
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary DNAs from 16 species of archaebacteria including 6 novel isolates were hybridized with 16S rRNAs from 7 species representing different orders or groups of the urkingdom of archaebacteria. The yields, normalized for the number of genes perµg of DNA, and the temperature stabilities of all hybrids were determined and related to each other. A taxonomic tree constructed from such fractional stability data reveals the same major divisions as that derived from comparative cataloging of 16S rRNA sequences. The extreme halophiles appear however as a distinct order besides the three known divisions of methanogens. The methanogens, the halophiles andThermoplasma form one of two clearly recognizable branches of the archaebacterial urkingdom. The order represented bySulfolobus and the related novel orderThermoproteales form the other branch. Three novel genera,Thermoproteus, Desulfurococcus and the “stiff filaments” represent three families of this order. The extremely thermophilic methanogenMethanothermus fervidus belongs to theMethanobacteriales. SN1, a methanogen from Italy, appears as another species of the genusMethanococcus. Another novel methanogen, M3, represents a genus or family of the orderMethanomicrobiales.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01810829
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  • 15
    Digitale Medien
    Digitale Medien
    Biochemical and genetic consequences of gene transfer from endosymbiont to host genome (1982)
    Springer
    Journal of molecular evolution 18 (1982), S. 287-292 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Endosymbiosis ; Gene transfer ; Transmembrane movement of proteins ; Receptors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In the origin of the mitochondrion and plastid, gene transfer from the ancestral endosymbiont to the host was proposed to be a crucial event. For this genic integration to proceed, products of transferred genes had to return to and enter the endosymbionts. The limiting event was the crossing of the barrier presented by the two semipermeable membranes bounding the proto-organelle. In this paper it is suggested that spontaneous transport allowed transferred gene encoded proteins to enter the endosymbionts before receptors evolved. The effects of these events, including the degeneration of the endosymbiont genome, are discussed. Although the presumed gene transfer had profound effects on the metabolic relationships between host and endosymbionts it probably cannot account for all examples of organelle/cytoplasmic isozyme pairs or the absence of amino acid synthetic enzymes in animal cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01733893
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  • 16
    Digitale Medien
    Digitale Medien
    Globular proteins, GU wobbling, and the evolution of the genetic code (1982)
    Springer
    Journal of molecular evolution 19 (1982), S. 20-27 
    Details
    ISSN: 1432-1432
    Schlagwort(e): GU base pairing ; RNA replication ; Globular proteins ; Genetic code ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary It has previously been shown that the formation of GU base pairs in RNA copying processes leads to an accumulation of G and U in both strands of the replicating RNA, which results in a non-random distribution of base triplets. In the present paper, this distribution is calculated, and, using the χ2-test, a correlation between the distribution of triplets and the amino acid composition of the evolutionarily conservative interior regions of selected globular proteins is established. It is suggested that GU wobbling in early replication of RNA could have led to the observed amino acid composition of present-day protein interiors. If this hypothesis is correct, the GU wobbling must have been very extensive in the imprecisely replicating RNA, even reaching values close to the critical for stability of its double-helical structure. Implications of the hypothesis both for the evolution of the genetic code and of proteins are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02100220
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  • 17
    Digitale Medien
    Digitale Medien
    The evolutionary pattern of aromatic amino acid biosynthesis and the emerging phylogeny of pseudomonad bacteria (1983)
    Springer
    Journal of molecular evolution 19 (1983), S. 272-282 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Microbial phylogeny ; Evolution ; Aromatic biosynthesis ; Regulatory enzymes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Pseudomonad bacterial are a phylogenetically diverse assemblage of species named within contemporary genera that includePseudomonas, Xanthomonas andAlcaligenes. Thus far, five distinct rRNA homology groups (Groups I through V) have been established by oligonucleotide cataloging and by rRNA/DNA hybridization. A pattern of enzymic features of aromatic amino acid biosynthesis (enzymological patterning) is conserved at the level of rRNA homology, five distinct and unambiguous patterns therefore existing in correspondence with the rRNA homology groups. We sorted 87 pseudomonad strains into Groups (and Subgroups) by aromatic pathway patterning. The reliability of this methodology was tested in a blind study using coded cultures of diverse pseudomonad organisms provided by American Type Culture Collection. Fourteen of 14 correct assignments were made at the Group level (the level of rRNA homology), and 12 of 14 correct assignments were made at the finer-tuned Subgroup levels. Many strains of unknown rRNA-homology affiliation had been placed into tentative rRNA groupings based upon enzymological patterning. Positive confirmation of such strains as members of the predicted rRNA homology groups was demonstrated by DNA/rRNA hybridization in nearly every case. It seems clear that the combination of these molecular approaches will make it feasible to deduce the evolution of biochemical-pathway construction and regulation in parallel with the emerging phylogenies of microbes housing these pathways.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02099974
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  • 18
    Digitale Medien
    Digitale Medien
    Order and orientation of genic sequences in circular mitochondrial DNA fromSaccharomyces exiguus: Implications for evolution of yeast mtDNAs (1983)
    Springer
    Journal of molecular evolution 19 (1983), S. 333-341 
    Details
    ISSN: 1432-1432
    Schlagwort(e): mtDNA ; Gene mapping ; Evolution ; Yeasts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Mapping of sequences specifying the large and small ribosomal RNAs and six polypeptides in the circular 23.7 kbp mitochondrial DNA ofSaccharomyces exiguus has shown that these genes have the same orientation and that a 5 gene cluster is common to this DNA and the 18.9 kbp mtDNA fromTorulopsis glabrata. Included in the preserved region are juxtaposed sequences specifying ATPase subunits 6 and 9 which have the same order and orientation as analogous genes in theEscherichia coli unc operon. The above data, together with knowledge that these two sequences are dispersed in larger yeast mtDNAs, leads us to suggest that larger forms are derived from a smaller ancestral molecule that would have had some resemblance to the mtDNAs ofS. exiguus andT. glabrata.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02101636
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  • 19
    Digitale Medien
    Digitale Medien
    Analysis of a five gene cluster and unique orientation of large genic sequences inTorulopsis glabrata mitochondrial DNA (1983)
    Springer
    Journal of molecular evolution 19 (1983), S. 342-345 
    Details
    ISSN: 1432-1432
    Schlagwort(e): mtDNA ; Gene mapping ; Evolution ; Yeasts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Analysis of gene order and orientation in the circular 18.9 kbp mitochondrial DNA molecule ofTorulopsis glabrata has shown that the eight large genic sequences have the same orientation and that a five gene cluster which runs — cytochrome b, cytochrome oxidase subunit 1, ATPase subunits 6 and 9 and cytochrome oxidase subunit 2 — is common to this DNA andSaccharomyces exiguus mtDNA (see accompanying paper).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02101637
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  • 20
    Digitale Medien
    Digitale Medien
    tRNA-rRNA sequence homologies: Evidence for a common evolutionary origin? (1983)
    Springer
    Journal of molecular evolution 19 (1983), S. 420-428 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Yeast ; E. coli ; tRNA ; rRNA ; Sequence homologies ; Evolution ; Origins ; Coding mechanism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Many tRNAs ofE. coli and yeast contain stretches whose base sequences are similar to those found in their respective rRNAs. The matches are too frequent and extensive to be attributed to coincidence. They are distributed without discernible pattern along and among the RNAs and between the two species. They occur in loops as well as in stems, among both conserved and non-conserved regions. Their distributions suggest that they reflect common ancestral origins rather than common functions, and that they represent true homologies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02102317
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  • 21
    Digitale Medien
    Digitale Medien
    Classification of elapid snake neurotoxins and cytotoxins according to chain length: Evolutionary implications (1984)
    Springer
    Journal of molecular evolution 20 (1984), S. 128-134 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Snake venom ; Neurotoxin ; Cytotoxin ; Evolution ; Circular dichroism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The amino acid sequences of the 139 homologous “short” neurotoxins, “long” neurotoxins and cytotoxins so far characterised from elapid snake venoms were compared on the basis of the amino acid deletion/insertion events that have occurred during evolution. Systematic grouping of the toxins according to similarity suggests that the short neurotoxins resemble the cytotoxins more closely than they do the long neurotoxins. The significance of this finding is discussed in relation to the methodology, the conformations of the toxins (as represented by circular dichroism spectra) and the outcome of the study that would have been obtained had more traditional methods been used. It appears probable that the cytotoxins evolved relatively recently from neurotoxic ancestors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02257373
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  • 22
    Digitale Medien
    Digitale Medien
    Temperature as a determinative factor in the evolution of genetic systems (1984)
    Springer
    Journal of molecular evolution 21 (1984), S. 72-75 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Heat ; Rates of copy error ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Heat induces a number of premutational lesions (for example, the deamination of cytosine to uracil) in DNA and RNA. These kinds of errors occur in resting as well as replicating polynucleotides. However, an increase in temperature also raises the probability of copying error occurring in nucleic acids because of increased thermal noise in the replicative machinery. In most modern genetic systems, the majority of heat-induced lesions are efficiently repaired. It follows that the importance of heat-induced error increases as the effectiveness of repair declines. We show in this paper that the error rate of enzymatic polynucleotide copying is expected to increase monotonically with temperature. We also explore the effects of temperature variations on the early evolution of biological information transmission mechanisms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02100629
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  • 23
    Digitale Medien
    Digitale Medien
    Adaptation ofDrosophila enzymes to temperature. III. Evolutionary conservatism in mitochondrial enzymes (1980)
    Springer
    Journal of molecular evolution 16 (1980), S. 37-46 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Drosophila ; Temperature ; Mitochondrial enzymes ; Kinetic properties
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The evolutionary behavior of two mitochondrial enzymes (L-glycerol 3-phosphate:cytochrome c oxidoreductase E.C.1.1.1.95,αGPO, and L-malate: NAD+ oxidoreductase, E.C.1.1.1.37, m-MDH) obtained from several temperate and tropicalDrosophila species was examined by comparing their catalytic properties, which related to temperature (Km-Ea-Q10-Thermostability). MitochondrialαGPO or m-MDH obtained either from temperate or from tropical species was found to exhibit similar catalytic properties while for both cytosolic enzymes, theαGPDH and s-MDH, Km patterns were similar among species from the same thermal habitat and different between thermal habitats. In combination with other observations reported in the literature these facts support the view that the function, and probably the structure, of mitochondrial enzymes are better conserved in evolution than those of the corresponding enzymes found in the cytosol. It is proposed that the relative invariance of the mitochondrial enzymes structure is probably linked to a necessary relative invariance of molecular interactions inside the mitochondrion.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01732068
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  • 24
    Digitale Medien
    Digitale Medien
    Evolution of patterns of gene expression in Hawaiian picture-wingedDrosophila (1980)
    Springer
    Journal of molecular evolution 16 (1980), S. 73-94 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Enzymes ; Evolution ; Gene regulation ; HawaiianDrosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The tissue and stage specificity of expression of five enzymes was examined by electrophoretic analysis of relative enzyme levels in extracts of 13 larval and adult tissues in 27 species of Hawaiian picture-wingedDrosophila. The developmentally regulated patterns of enzyme expression thus characterized were compared to a modal standard phenotype. About 30% of the pattern features analyzed differed significantly from the standard in one or more species. Many of these regulatory differences are essentially qualitative, with tissue specific differences in enzyme activity in excess of 100 fold for some species pairs. The adaptive significance of these pattern differences is unknown, but the results provide strong direct evidence for rapid evolution of new patterns of gene regulation in this group of organisms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01731579
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  • 25
    Digitale Medien
    Digitale Medien
    Tubulin evolution: Two major types of α-tubulin (1982)
    Springer
    Journal of molecular evolution 19 (1982), S. 80-86 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Microtubules ; Tubulin ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Tubulin subunits have been isolated from a variety of protists and marine invertebrates. The sources were: sperm tails of a tunicate (Ciona intestinalis), an abalone (Haliotis rufescens) and a sea anemone (Tealia crassicornis), the gill cilia of a clam (Mercenaria mercenaria), the cilia of a ciliate (Tetrahymena pyriformis) and the cytoplasm of a slime mold (Physarum polycephalum). All the β-tubulins, as characterised by their electropherograms after limited proteolytic cleavage withStaphylococcus aureus protease, were fairly similar. In contrast, two markedly different peptide patterns were found for the α-tubulins of (a) metazoan axonemes and (b) protistan axonemes, plant axonemes and slime mold cytoplasm. Metazoan axonemal α-tubulin peptide patterns could be further divided into two similar but distinct subtypes which did not correlate with the taxonomic divisions of deuterostomia and protostomia, or to different tubulins within an axoneme, or to different tubulins of flagella and cilia. We have postulated that these small differences may be accounted for by a simple glutamicaspartic acid exchange at a particular position in the α-tubulin sequence. Identical peptide patterns were observed for sea urchin and sea anemone sperm tail tubulins, proving that the metazoan type of axonemal tubulin arose before the divergence of bilateral and radial symmetric organisms. The close similarity of the slime mold cytoplasmic α-tubulin peptide pattern to protistan and plant axonemal α-tubulin patterns suggests that the same type of tubulin might be used to form both axonemal and cytoplasmic types of microtubules in protists and plants. The large structural constraints imposed upon this tubulin molecule probably allowed very little change in its primary structure, thus explaining the similarity of tubulins from organisms which diverged at such an early time in eukaryote history. Duplication and modification of the tubulin gene may then have led to the development of specific axonemal and cytoplasmic microtubules during the evolution of the metazoa.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02100226
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  • 26
    Digitale Medien
    Digitale Medien
    Evolution ofDrosophila repetitive-dispersed DNA (1983)
    Springer
    Journal of molecular evolution 19 (1983), S. 203-213 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Phylogenetic distribution ; Repetitive-dispersed DNAs ; Speciation ; Transposons
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have examined the phylogenetic distribution of a spectrum ofDrosophila repetitive-dispersed DNAs ranging from structurally complex transposable elements to scrambled middle repetitive sequences. Our data suggest that unlike typical “genes” these DNAs are unstable components of the drosophilid genome. The unusual behavior of these repetitive-dispersed DNAs raises the possibility that this type of sequence may have an important role in the evolution of the family Drosophilidae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02099967
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  • 27
    Digitale Medien
    Digitale Medien
    Balbiani ring DNA: Sequence comparisons and evolutionary history of a family of hierarchically repetitive protein-coding genes (1984)
    Springer
    Journal of molecular evolution 20 (1984), S. 281-295 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Balbiani ring ; Repeat ; Evolution ; Repetitive DNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary All known types of Balbiani ring (BR) gene consist of multiple, tandemly arranged, ca. 180 to 300-bp repeat units that can be divided into a constant region and a subrepeat region. The latter region includes short tandem subrepeats (SRs). Comparison of all available BR sequences using computer methods has enabled us (a) to define more precisely the constant and subrepeat regions, (b) to infer the evolutionary relationships among the various types of BR repeats, (c) to derive a consensus approximation of an ancestral sequence from a small segment of which the highly diverse present-day SRs may have originated, and (d) to detect an underlying substructure in the constant region, evident in the consensus but not in the present-day sequences and possibly corresponding to an original 39-bp DNA segment from which the extant, giant BR sequences may have evolved. We discuss the processes of reduplication, diversification, and homogenization within the hierarchically repetitive BR sequences as examples of how a simple DNA element may evolve into a diverse family of large, protein-coding genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02104734
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  • 28
    Digitale Medien
    Digitale Medien
    Conserved and nonconserved structures in the secretory proteins encoded in the Balbiani ring genes ofChironomus tentans (1984)
    Springer
    Journal of molecular evolution 20 (1984), S. 304-312 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Gene family ; Balbiani ring genes ; Repetitive sequences ; Structural proteins ; Protein conformation ; Polymerization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The large, repetitive Balbiani ring (BR) genes, BR 1, 2, and 6, inChironomus tentans originated from a short ancestral sequence and have all evolved according to analogous amplification schemes. We analyzed the structures of the BR-encoded secretory proteins and defined the parts that have been conserved during the evolutionary process. The BR products show striking similarities, with the BR 1 and BR 2 products being more similar to each other than to the BR 6 product. In the constant (C) region of the repeat units, 7 of the 30 amino acid residues are strictly conserved; 4 of these are the cysteine residues. The subrepeat (SR) regions of all the BR products are dominated by repeated tripeptide elements rich in proline and charged amino acid residues. Most of the amino acid replacements in both regions are conservative. Secondary structure predictions suggested that the C regions of the BR 1 and BR2 products have several elements of secondary structure: an α-helix, a β-strand, and one or two reverse turns, as in “globular structures.” The prediction for the C region of the BR 6 product is similar but lacks a β-strand. The predictions for the intervening SR regions appear less conclusive, but are clearly different from those for the C regions, and suggest regular structures not differing in their conformational elements. The SR regions evolved from an ancestor sequence similar to the C region; thus, the BR products seem to represent an example of evolution from one structure to two differently folded products. It is proposed that the alignment and polymerization of the long BR proteins could be promoted by the repetitive structure of the molecules, due to the possibility of forming disulfide bridges between half-cystine residues and electrostatic interactions between the charged residues of the SR regions. The divergence among the BR products is discussed in relation to possible functional differences among the members of the BR gene family.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02104736
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  • 29
    Digitale Medien
    Digitale Medien
    The case for a polyphyletic origin of mitochondria: Morphological and molecular comparisons (1984)
    Springer
    Journal of molecular evolution 21 (1984), S. 54-57 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Mitochondrion ; Cytochrome C ; Rhodospirillaceae ; Endosymbiosis ; rRNA ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The comparative morphology and pigmentation of protists suggest that those with tubular mitochondrial cristae belong to a different lineage than those with lamellar cristae and that the evolutionary divergence might have been very early. We propose that the difference in cristal morphology is the result of separate origins of the mitochondria from endosymbionts related to the Rhodospirillaceae (purple nonsulfur bacteria) but differing in the morphology of their internal membranes. Comparisons of the cytochromes c of protists and the Rhodospirillaceae and of 16s rRNA T1 oligonucleotide catalogs in the Rhodospirillaceae do not contradict, and in fact provide support for, the idea. More extensive evidence may be lacking simply because cytochromes c have been studied in very few protists with tubular mitochondrial cristae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02100627
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  • 30
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Plastid DNA ; Cytochrome b6 gene ; Amino acid sequence ; Hydropathy ; Thylakoid membrane ; Transcript modification ; Evolution ; Spinach
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00410442
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  • 31
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Superoxide dismutase ; Glutamine synthetase ; Evolution ; Marine bacteria ; Alcaligenes ; Alteromonas ; Deleya ; Oceanospirillum ; Pseudomonas
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00413018
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  • 32
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Glycogen ; Archaebacteria ; Thermoacidophiles ; Sulfolobus ; Thermoproteales ; Glucosyl transferase ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00413378
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  • 33
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Evolution ; Vibrio ; Photobacterium ; Alteromonas ; Aeromonas ; Marine bacteria ; Superoxide dismutase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00411061
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  • 34
    Digitale Medien
    Digitale Medien
    Cell lineage restrictions in the genital disc ofDrosophila revealed byMinute gynandromorphs (1983)
    Springer
    Development genes and evolution 192 (1983), S. 337-346 
    Details
    ISSN: 1432-041X
    Schlagwort(e): Drosophila ; Gynandromorphs ; Genital disc ; Compartments ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The genital imaginal disc ofDrosophila differentiates the terminalia, i.e. the genitalia and analia, of both sexes. It represents a composite anlage, containing a female genital primordium, a male genital primordium and an anal primordium. In normal males and females, only one of the two genital primordia differentiates; the other is developmentally repressed. Therefore, cell-lineage relationships between the male and female genital primordia can only be studied in sexual mosaics which differentiate female and male cells. We producedMinute (M)‖non-Minute(M+) gynandromorphs and selected those with sexually mosaic terminalia for a cell-lineage analysis. In these mosaics, either the male (XO) or female (XX) cells wereM + and thus had a growth advantage. The differential growth rates served as a tool to detect clonal restrictions. In control gynandromorphs (M +‖M +), the amount of female genitalia differentiated was largely independent of the amount of male genitalia present. In contrast, male and female anal structures, as a rule, added up to one full set. The same was true for the experimentalM‖M + gynandromorphs, but the contribution ofXX andXO cells to mosaic terminalia changed drastically due toM + cells competing successfully against the more slowly growingM cells. Specific subsamples ofM‖M + gynandromorphs showed thatM cells in a non-mosaic primordium are shielded from cell competition taking place in the neighbouring mosaic primordium. We conclude that the three primordia of the genital disc represent developmental compartments. In the genital primordia, even developmentally repressedM + cells compete successfully against developmentally activeM cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00848814
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  • 35
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Endosperm ; Evolution ; Interspecific crosses ; Solanums ; 2n gametes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00276002
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  • 36
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Conifers ; Deciduous tree ; Polyploidy ; Endoploidy ; Evolution ; Cytophotometry ; DNA content
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00279713
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  • 37
    Digitale Medien
    Digitale Medien
    Nicotiana chloroplast genome III. Chloroplast DNA evolution (1982)
    Springer
    Theoretical and applied genetics 61 (1982), S. 73-79 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Nicotiana ; Chloroplast DNA ; Restriction fragments ; Deletion ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00261515
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  • 38
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Cultivated potato ; Evolution ; Parallel spindles ; 2n gametes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00273885
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  • 39
    Digitale Medien
    Digitale Medien
    Utilization of wild relatives in genetic improvement of Arachis hypogaea L. (1982)
    Springer
    Theoretical and applied genetics 61 (1982), S. 305-314 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Arachis ; Karyomorphology ; D2 analysis and genetic distance ; Evolution ; Crop improvement
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00272846
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  • 40
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Diploid pollen ; Evolution ; Sexual polyploidization ; Solanum ; Tuberosa ; Diplandroids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00264421
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  • 41
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Electrophoresis ; Proteins ; Leguminosae ; Taxonomy ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00264675
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  • 42
    Digitale Medien
    Digitale Medien
    Cross-incompatibility between two sympatric polyploid Solanum species (1981)
    Springer
    Theoretical and applied genetics 60 (1981), S. 65-70 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Cross-incompatibility ; Solanum ; Reproductive barriers ; Introgression ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00282417
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  • 43
    Digitale Medien
    Digitale Medien
    “Complement fractionation” in natural diploid orchid species (1982)
    Springer
    Theoretical and applied genetics 61 (1982), S. 91-95 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Complement fractionation ; Excess sporads ; Diploid orchid species ; Phaius tribe ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00261517
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  • 44
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Chromosomes ; Nucleotides ; Evolution ; Polyploids ; Triticum ; Heterochromatin ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00303906
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  • 45
    Digitale Medien
    Digitale Medien
    Can the theory of evolution be falsified? (1984)
    Springer
    Acta biotheoretica 33 (1984), S. 35-50 
    Details
    ISSN: 1572-8358
    Schlagwort(e): Evolution ; falsification ; Darwinism ; philosophy of science
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In this paper we discuss the epistemological positions of evolution theories. A sharp distinction is made between the theory that species evolved from common ancestors along specified lines of descent (here called “the theory of common descent”), and the theories intended as causal explanations of evolution (e.g. Lamarck's and Darwin's theory). The theory of common descent permits a large number of predictions of new results that would be improbable without evolution. For instance, (a) phylogenetic trees have been validated now; (b) the observed order in fossils of new species discovered since Darwin's time could be predicted from the theory of common descent; (c) owing to the theory of common descent, the degrees of similarity and difference in newly discovered properties of more or less related species could be predicted. Such observations can be regarded as attempts to falsify the theory of common descent. We conclude that the theory of common descent is an easily-falsifiable & often-tested & still-not-falsified theory, which is the strongest predicate a theory in an empirical science can obtain. Theories intended as causal explanations of evolution can be falsified essentially, and Lamarck's theory has been falsified actually. Several elements of Darwin's theory have been modified or falsified: new versions of a theory of evolution by natural selection are now the leading scientific theories on evolution. We have argued that the theory of common descent and Darwinism are ordinary, falsifiable scientific theories.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00045845
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  • 46
    Digitale Medien
    Digitale Medien
    Mutation breeding of grain legumes (1984)
    Springer
    Plant and soil 82 (1984), S. 337-357 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Evolution ; Grain legumes ; Induced mutations ; Mutation breeding ; Symbiotic nitrogen fixation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Grain legumes are an important group of crop plants. They provide an essential source of protein food for many developing countries, but their production has gone down in favour of more profitable crops like cereals. Therefore, genetic improvement of grain legumes is urgently needed. The primary aim of grain legume breeding must be the increase of production through adaptation to more advanced cropping schemes and reduction of crop losses. Symbiotic nitrogen fixation as developed by natural evolution does not always seem to be compatible with the needed substantial increase in yield: It is not supplying sufficient nitrogen and supplementation by fertilizer is rather uneconomic. By genetic manipulation of the plant's regulatory system nitrogen fixation may become more effective and tolerant to high soil nitrogen levels. Through a number of mutation breeding projects in different countries involving all important grain legume species it has been proven that mutation induction is a good tool for supplementing the genetic variation available from natural evolution and from selection by man. High-yielding cultivars have been developed from induced mutants, which eventually also possess a more efficient nitrogen fixation capacity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02184272
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  • 47
    Digitale Medien
    Digitale Medien
    Seasonality in habitat selection by the gold color morph of Cichlasoma citrinellum and its relevance to sympatric speciation in the family Cichlidae (1980)
    Springer
    Environmental biology of fishes 5 (1980), S. 75-78 
    Details
    ISSN: 1573-5133
    Schlagwort(e): Cichlid ; Ecology ; Behavior ; Evolution ; Tropics ; Polymorphism ; Central America ; Lake Malawi ; Africa
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis Cichlasoma citrinellum is a polymorphic species whose individual coloration varies from the dark grey markings typical of the species to yellow, orange, and red. In Lake Jiloá, Nicaragua the depth distribution of these latter, nongrey, golden morphs shows dramatic seasonal variation. In the height of the dry season in February over 50% of the gold morphs occur above 9 m, but as the breeding season approaches they migrate deeper such that less than 7% of the gold population occurs above 9 m at the onset of the breeding season. During the rainy season when breeding occurs most of the gold morphs occur below 15 m. It appears that gold morphs ‘voluntarily’ move into deeper water to breed rather than being aggressively forced deeper by larger, territorial grey morphs as was implied in an earlier paper (McKaye & Barlow 1976). Since the morphs of this species assortatively mate and select different habitats in which to breed, future sympatric splitting of this species is possible. Likely examples of sympatric speciation and of incipient speciation in the family Cichlidae are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00000953
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  • 48
    Digitale Medien
    Digitale Medien
    Growth parameters for typical anadromous and dwarf stocks of alewives,Alosa pseudoharengus (Pisces, Clupeidae) (1983)
    Springer
    Environmental biology of fishes 9 (1983), S. 277-287 
    Details
    ISSN: 1573-5133
    Schlagwort(e): Freshwater adaptation ; Heavy metals ; Heterochrony ; Landlocked ; Larval period ; Migration ; Ontogeny ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis Growth parameters for anadromous alewives,Alosa pseudoharengus (Clupeidae) from two Gulf of Maine watersheds are described. Fish from Damariscotta Lake are typical of other coastal anadromous stocks whereas fish from Walker Pond are dwarfs. The dwarf stock has a life history pattern intermediate between that of fully landlocked and typical anadromous stocks. The dwarfs are anadromous but their young remain in freshwater approximately 16 months, compared to the 2 to 4 months typical of anadromous stocks. This prolonged period of freshwater residence includes a greatly extended larval period and a reduced growth rate. The data suggest that the principal adaptive interval in alewife life history occurs during early ontogeny and that variations in larval development may be the basis for the evolution of fully landlocked stocks from anadromous ancestors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00692376
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  • 49
    Digitale Medien
    Digitale Medien
    Reproduction of weakly electric teleosts: just another example of convergent development? (1984)
    Springer
    Environmental biology of fishes 10 (1984), S. 3-14 
    Details
    ISSN: 1573-5133
    Schlagwort(e): Mormyriforms ; Gymnotiforms ; Communication ; Spawning cues ; Circannual cycles ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00001658
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  • 50
    Digitale Medien
    Digitale Medien
    On the conservative nature of the gill filaments of sharks (1984)
    Springer
    Environmental biology of fishes 10 (1984), S. 111-116 
    Details
    ISSN: 1573-5133
    Schlagwort(e): Branchial canopy ; Evolution ; Interbranchial septum ; Isurus oxyrinchus ; Passive gill ventilation ; Prionace glauca ; Ram gill ventilation ; Secondary lamellae ; Sphyrna zygaena
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis Gill filaments of one highly active and two less active shark species exhibit a conservative morphological scheme including such features as branchial canopies, marginal lamellar projections, and enlarged, discrete outer marginal lamellar channels and lateral lamellar sinuses. The specific spatial orientation of the secondary lamellae respective to one another, the gill filaments, and the interbranchial septa create what appears as one-way interfilament water channels, suggesting the presence of an efficient branchial countercurrent system. It is proposed that the fortified structure of shark gills allows many shark species to ventilate passively without having evolved gill filament modifications as apparently did some highly active teleosts. This in turn may have expedited the evolution of lamnid shark species through pre-adaptation to a swift oceanic lifestyle.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00001667
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  • 51
    Digitale Medien
    Digitale Medien
    Midwater spawning inHaplochromis chrysonotus (Boulenger) (Teleostei: Cichlidae) in Lake Malawi (1981)
    Springer
    Environmental biology of fishes 6 (1981), S. 201-202 
    Details
    ISSN: 1573-5133
    Schlagwort(e): Mouth brooding ; Breeding behaviour ; Pelagic lifestyle ; Courtship ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis Haplochromis chrysonotus, a semipelagic shoaling cichlid from Lake Malawi, has been observed spawning in open water up to ten metres above the substratum. It is suggested that open water spawning without the establishment of a substratum-based territory eliminates competition with other species for breeding space and that it may be a stage in the evolution of a totally pelagic mode of life.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00002783
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  • 52
    Digitale Medien
    Digitale Medien
    Social grouping and genetic variation in common shiners, Notropis cornutus (Pisces, Cyprinidae) (1981)
    Springer
    Environmental biology of fishes 6 (1981), S. 357-360 
    Details
    ISSN: 1573-5133
    Schlagwort(e): Behaviour ; Esterase ; Evolution ; Genetics ; Isozymes ; Stock structure ; Schools ; Starch gel
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis Heterogeneous gene frequencies of Est-1 across groups ofNotropis cornutus provide evidence of behaviourally imposed restrictions on stock structuring. Positive fixation indices (F1S = 0.056 and F1T = 0.085) were reflected by a deficiency of heterozygotes for pooled groups. The degree of subdivision ofN. cornutus stocks cannot be evaluated with the present evidence. but it is likely that their schooling behaviour is associated with significant genotypic structuring of the species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00005765
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  • 53
    Digitale Medien
    Digitale Medien
    Scale-eating in characoids and other fishes (1983)
    Springer
    Environmental biology of fishes 9 (1983), S. 87-101 
    Details
    ISSN: 1573-5133
    Schlagwort(e): Feeding habits ; Lepidophagy ; Evolution ; Behavior ; Predation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis Scale-eating is known for several unrelated fish groups, but few data are available on the habits of most species. General habits and feeding behavior of some lepidophagous characoids are presented and compared to other scale-eating species. The diversity of morphology, habits, and behavior of scale-eating fishes is great, and few patterns are shared by the specialized scale-eaters. Except for modified teeth, no morphological characteristic permits identifying a fish as a specialized lepidophage. Hunting tactics consist mainly of ambush, stalking, or disguise (aggressive mimicry). Scale-removal may be accomplished by a jarring strike with the snout, generally directed at the prey's flank, or by biting or rasping. The mode of scale-removal seems to reflect primarily the disposition of the jaws and the teeth. Scales are swallowed directly if taken in the mouth; if not, they are gathered as they sink, or picked up from the bottom. Scale-eating is probably a size-limited habit. Specialized scale-eaters rarely exceed 200 mm, most ranging near 120 mm. Some species eat scales only when young; most take other food items in addition to scales. Scale-eating habits probably arose from trophic or social behaviors. These are not mutually exclusive and, indeed, may have acted together during the evolution of lepidophagy. Suggested trophic origins include scraping epilithic algae, modified piscivory, and necrophagy. Social origins include intra- and interspecific aggressive behavior during feeding.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00690855
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  • 54
    Digitale Medien
    Digitale Medien
    Changes in DNA composition in the evolution of Vicia species (1984)
    Springer
    Theoretical and applied genetics 68 (1984), S. 187-192 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Vicia ; nuclear DNA ; Evolution ; Base sequence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00252337
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  • 55
    Digitale Medien
    Digitale Medien
    A light and electron microscopic study of stigmas inAneilema andCommelina species (Commelinaceae) (1982)
    Springer
    Protoplasma 112 (1982), S. 26-36 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Aneilema ; Commelina ; Cytochemistry ; Evolution ; Papillae ; Pollination ; Secretion ; Stigmas ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01280212
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  • 56
    Digitale Medien
    Digitale Medien
    An ultrastructural and histochemical study of the axial musculature in the African lungfish (1981)
    Springer
    Cell & tissue research 220 (1981), S. 599-609 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Axial musculature ; Lungfish ; Histochemistry ; Ultrastructure ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Red, intermediate, and white axial muscle fibres of African lungfish were studied using histochemical techniques and electron microscopy. Gross dissection revealed the presence of a small wedge of red coloured muscle along the lateral line. This wedge was shown by histochemical demonstrations of lactate and succinate dehydrogenases, of adenosine triphosphatases, and of lipid to be composed of a mosaic of red and intermediate fibres measuring 23.63 and 34.30 μm in average diameter, respectively. The bulk of the myotome was composed of white fibres having an average diameter of 67.35 μm. Mitochondrial density, capillarity and lipid content were very low for all fibres. These data suggest that the axial musculature is geared primarily for anaerobic function. The mosaic arrangement of fibres, and the lack of a subsarcolemmal band of mitochondria suggests that the lungfish have a muscle organisation that is transitional between lower vertebrates and amphibians.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00216763
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  • 57
    Digitale Medien
    Digitale Medien
    An immunocytochemical study of endocrine pancreas of snakes (1984)
    Springer
    Cell & tissue research 235 (1984), S. 657-661 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Evolution ; Endocrine pancreas ; Regulatory peptides ; Snakes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00226965
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  • 58
    Digitale Medien
    Digitale Medien
    The hypothalamic-hypophyseal system and its evolutionary aspects in Scyliorhinus caniculus (1981)
    Springer
    Cell & tissue research 214 (1981), S. 575-582 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Hypothalamic-hyphophyseal system ; Scyliorhinus caniculus ; Neurointermediate cells ; Peptidergic terminals ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The peptidergic nature of most of the fibres of the neurosecretory system of Scyliorhinus caniculus has been demonstrated with the oxidation method of Naumann and Sterba (1976). Some of the fibres of this peptidergic system terminate on capillaries in the hypothalamic floor, some on neurointermediate cells. The evolutionary aspects of these observations are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00233497
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  • 59
    Digitale Medien
    Digitale Medien
    Some aspects of chromosome cytology in the cestodeAcanthotaenia multitesticulata (1980)
    Springer
    Parasitology research 63 (1980), S. 65-70 
    Details
    ISSN: 1432-1955
    Schlagwort(e): Chromosome ; Cytology ; Proteocephalid ; Cestode ; Gametogenesis ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The diploid chromosome number of the proteocephalid cestodeAcanthotaenia multitesticulata is reported for the first time to be fourteen from mitotic as well as meiotic stages of gametogenesis. A chiasma frequency of 2.42 was found. Variation in chromosome numbers in cestodes with reference to this parasite is discussed from an evolutionary point of view.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00927727
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  • 60
    Digitale Medien
    Digitale Medien
    Anatomy and evolution in MacaronesianEchium (Boraginaceae) (1981)
    Springer
    Plant systematics and evolution 138 (1981), S. 9-22 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Boraginaceae ; Echium ; Evolution ; anatomy ; paedomorphosis ; pachycauls ; tracheary elements ; wood rays ; stem anatomy ; Macaronesian flora
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00984605
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  • 61
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Bacillariophyta ; Bacillariaceae ; Nitzschia ; Raphe Structure ; Systematics ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00986414
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  • 62
    Digitale Medien
    Digitale Medien
    Inferred chromosome morphology of the ancestral genome ofTriticum (1984)
    Springer
    Plant systematics and evolution 144 (1984), S. 209-220 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Angiosperms ; Poaceae ; Triticum ; Elytrigia ; wheat ; Evolution ; genome ; karyotype
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00984134
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  • 63
    Digitale Medien
    Digitale Medien
    Karyotypic evolution, morphological variability and phylogeny inMedicago sect.Intertextae (1984)
    Springer
    Plant systematics and evolution 145 (1984), S. 203-222 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Fabaceae ; Leguminosae ; Medicago ciliaris ; Medicago intertexta ; Medicago muricoleptis ; Medicago granadensis ; Evolution ; chromosomes ; Pleistocene glaciations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00983949
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  • 64
    Digitale Medien
    Digitale Medien
    Fine structure of the sensory receptors of Aglantha digitale (Hydromedusae: Trachylina) (1983)
    Springer
    Cell & tissue research 231 (1983), S. 415-425 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Statocysts ; Ciliated comb pads ; Microvilli ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Fine-structure studies of the sensory receptors of Aglantha digitale have been done by transmission- and scanning-electron microscopy. Aglantha has 8 club-shaped statocysts and three types of ciliated sensory receptors: ciliated comb pads, ciliated sensory cells with microvilli, and ciliated sensory cells without microvilli. The epithelium covering the statocyst has both ciliated sensory cells and epitheliomuscular cells. The ciliated comb pads are formed by a group of ciliated sensory cells, each having an apical kinocilium surrounded by a ring of microvilli. These microvilli show an increase in length towards the velum. The axons from the comb pad cells enter the inner nerve ring. The structure, function and the evolution of the statocysts and the possible role of the ciliated comb pads and other sensory receptors are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00222191
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  • 65
    Digitale Medien
    Digitale Medien
    Regulatory peptides in the gastrointestinal tract of Alligator mississipiensis (1983)
    Springer
    Cell & tissue research 231 (1983), S. 439-449 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Evolution ; Regulatory peptides ; Gut ; Endocrine cells ; Peripheral innervation ; Alligator mississipiensis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The gastrointestinal tract of the alligator Alligator mississipiensis has been investigated for the presence of immunoreactivity to fourteen regulatory peptides all known to occur in the mammalian gut system. Mucosal endocrine cells reacting specifically with the antisera to neurotensin, C-terminal gastrin, somatostatin, bombesin, secretin, pancreatic glucagon and enteroglucagon were detectable, the distribution of these cells being, in general, similar to the mammalian pattern. Peripheral nerve cell bodies and nerve fibres were detected with the antisera to vasoactive intestinal polypeptide, substance P, bombesin and somatostatin again with a distribution similar to that seen in mammals. No immunoreactivity was observed with the available antisera to glicentin, motilin, gastric inhibitory polypeptide, gastrin 34, cholecystokinin 9–20 and met-enkephalin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00222193
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  • 66
    Digitale Medien
    Digitale Medien
    The endocrine pancreas of Alligator mississippiensis (1982)
    Springer
    Cell & tissue research 224 (1982), S. 117-128 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Endocrine pancreas (alligator) ; Endocrine cells ; Peptidergic nerves ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Immunocytochemical methods for light and electron microscopy were used to demonstrate the regulatory peptides present in the endocrine pancreas of thealligator, Alligator mississippiensis.The peptides studied included insulin, glucagon (pancreatic and enteric), somatostatin, pancreatic polypeptide (avian, bovine and human), vasoactive intestinal polypeptide, substance P, metenkephalin, β-endorphin, C-terminal gastrin/CCK and gastric inhibitory polypeptide. Endocrine cells were detected using antisera to insulin, pancreatic glucagon, somatostatin and avian pancreatic polypeptide, whereas peptidergic nerves were stained with antisera to vasoactive intestinal polypeptide. All other antisera were unreactive in the alligator pancreas. The peptide-containing structures were identified ultrastructurally by both the semithin/thin and immuno-gold methods. The results showed that five of the regulatory peptides commonly detected in the mammalian pancreas were immunologically recognisable in the alligator. In addition, the ultrastructural appearance of the peptide-containing cells was clearly distinct from that reported in mammals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00217271
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  • 67
    Digitale Medien
    Digitale Medien
    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 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Neocortex ; Evolution ; Development ; Plasticity ; Visual system
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234781
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