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  • 1
    Electronic Resource
    Electronic Resource
    Habitat selection in evolving mole rats (1979)
    Springer
    Oecologia 43 (1979), S. 125-138 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The actively speciating four chromosomal species of fossorial mole rats of the Spalax ehrenbergi complex in Israel (2n=52, 58, 54 and 60) which inhabit an increasingly arid environment in this order were tested to determine their habitat preference. The testing apparatus simulated four climatic regimes based on temperature and humidity combinations corresponding to the climatic origins of the four chromosomal species: coolhumid, cool-dry, warm-humid and warm-dry, respectively. The tests involved 175 adults comprising all four chromosome species and representing 10 populations. Out of the 139 analyzed animals 88% selected the warm cages and only 12% selected the cool cages. The four karyotype progressively preferred the warm-dry cage in the following order: 53, 59, 60 and 72% for 2n=58, 52, 54 and 60 respectively, largely in accord with their increasingly arid climatic origins. Even larger differences were found in populations within karyotypes in accord with the local climatic variation within a karyotype range. The results of our analysis indicate that the chromosomal species and populations select their climatic habitat in accord with the climatic conditions of their geographic localities. The humidity index appears to be the prime differentiator of habitat selection and may have been a substantial ecological factor in species differentiation and distribution of the Spalax ehrenbergi complex in Israel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00344766
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  • 2
    Electronic Resource
    Electronic Resource
    Relationships of the chromosomal species in the eurasian mole rats of theSpalax ehrenbergi group as determined by DNA-DNA hybridization, and an estimate of the spalacid-murid divergence time (1989)
    Springer
    Journal of molecular evolution 29 (1989), S. 223-232 
    Details
    ISSN: 1432-1432
    Keywords: Spalax speciation ; Rate of DNA change ; Rodent phylogeny ; DNA hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary DNA-DNA hybridization was used to measure the average genomic divergence among the four chromosomal species of the Eurasian mole rats belonging to theSpalax ehrenbergi complex (Rodentia: Spalacidae). The percent nucleotide substitutions in the single-copy nuclear DNA among the species ranged from 0 to 5%, suggesting that speciation has occurred with minor genomic changes in these animals. The youngest chromosomal species appear to differ by 0.2–0.6% base pair mismatch, which is only between one and three base differences in a 500-bp fragment. The interspecific values of percent nucleotide differences permit the recognition of two well-separated speciation events in theS. ehrenbergi complex, the older (of Lower Pleistocene age) having isolated the chromosomal species 2n=54 before the divergence of the three other species. DNA-DNA hybridization was also used to compare the Spalacinae (Eurasian mole rats), Murinae (Old World rats and mice), and Arvicolinae (voles and lemmings). These data enabled us to estimate the time of divergence of the spalacids at ca. 19 million years ago. The dates of divergence among the other rodent lineages, as predicted by DNA hybridization results, agree well with paleontological data. These dates of divergence are obtained by the relation between geological time and single-copy nuclear DNA change, a relation that was calibrated by Catzeflis et al. (1987) through the use of fossil Arvicolinae and Murinae data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02100206
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  • 3
    Electronic Resource
    Electronic Resource
    Genetic diversity and climatic determinants of tree frogs in Israel (1979)
    Springer
    Oecologia 41 (1979), S. 47-63 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Allozymic variation in proteins encoded by 27 loci was analyzed electrophoretically in 218 adult specimens, mostly males, representing 8 populations, 5 central and 3 marginal, of lemon yellow treefrogs, Hyla arborea savignyi, in Israel along two transects of increasing aridity: (a) north to south and (b) west to east. The results indicate that (a) Of the 27 loci examined, 5 are monomorphic in all 8 populations; 9 are locally and weakly polymorphic; 6 are regionally and weakly polymorphic; and 7 are regionally and strongly polymorphic; (b) In the populations studied, no alternative fixations were found in any of the 27 loci, except in the Wasit population. The commonest allele predominates across all populations, except Wasit, central as well as marginal; (c) Clinal patterns associated with increasing aridity southwards and eastwards occur in polymorphism, P, heterozygosity, H, and in allele frequencies of Ldh-1, Fum, Got-1, and Sdh; (d) For habitat generalists, treefrogs have above average number of alleles per locus, A, and polymorphism, P, while the heterozygosity, H, is average. All three estimates A, P, and H exhibit wide geographic variation decreasing progressively southwards and eastwards; (e) Central populations harbor more genic variation then marginal populations; (f) Genic similarity between populations is high; (g) Significant gametic phase disequilibria were found in several tests in 2 populations; (h) P, H, and allozymic variation in several gene loci are significantly correlated and predictable by environmental variables, primarily those related to water; (i) Morphological and allozymic variations are uncorrelated. The spatial patterns and environmental correlates and predictors of genic variation in Hyla arborea savignyi in Israel suggest that (i) protein polymorphisms are largely adaptive and are molded primarily by climatic selection rather than by stochastic processes or neutrality, and (ii) the environmental variation model seems to be the best predictor of genic variation in treefrogs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00344836
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  • 4
    Electronic Resource
    Electronic Resource
    Adaptive differentiation of body size in speciating mole rats (1986)
    Springer
    Oecologia 69 (1986), S. 327-333 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We report the body weight of 1,653 subterranean mole rats comprising 12 populations and 4 chromosomal species (2n=52, 54, 58 and 60) of the Spalax ehrenbergi superspecies in Israel. The sample was collected from 1970 to 1985 and includes all captured animals with a minimal age of 10 months. The results indicated the following. (a) Body weight of males was significantly higher than that of females. (b) There is a southward latitudinal gradient in body size. Northern animals living in cooler and more productive mesic environments are larger than southern animals living in warmer and less productive xeric environments. (c) The interspecific differences for each sex are statistically significant. (d) Body size is negatively correlated with temperature variables, and positively correlated with plant cover (reflecting productivity or food resources) and rainy days. (e) The best predictors of body size, explaining up to 87% of the variation in size included various combinations of temperature variables and plant cover. We conclude that in both adaptation and speciation natural selection is a major agent of differentiation of body size in accordance with multiple factors, primarily temperature and food resources operating on the energetics balance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377052
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  • 5
    Electronic Resource
    Electronic Resource
    Adaptive variation of pelage color within and between species of the subterranean mole rat (Spalax ehrenbergi) in Israel (1988)
    Springer
    Oecologia 74 (1988), S. 617-622 
    Details
    ISSN: 1432-1939
    Keywords: Pelage color ; Differential predation ; Adaptive variation ; Subterranean mammals ; Spalax ehrenbergi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Color notations of dorsal pelage were analyzed in 451 adult subterranean mole rats, comprising 19 populations and 4 chromosomal species (2n=52, 54, 58 and 60) of the Spalax ehrenbergi superspecies in Israel. In addition, the color notations of soil samples from the collection sites were measured. In an attempt to evaluate the degree of correlation between pelage color of mole rats and the local soil color, each color was compared both macro- and microgeographically. The macrogeographic comparisons were among populations of the 4 chromosomal species, and the microgeographic comparisons were among pairs of geographically neighboring subpopulations which occur under similar climatic conditions but differ in soil type and color. The results indicate that 1. no differences in pelage color notation exist between the sexes; 2. pelage of mole rats is generally characterized by an over-all grayish color, but its shades vary regionally and locally in accordance with varying soil color; 3. a positive correlation was found between pelage and local soil colors in the macrogeographic analysis and this correlation was verified in a microgeographic comparison; 4. specimens from populations of the northern chromosomal species (2n=52, 54) mainly inhabit terra rossa and basalt soils, respectively, with reddish brown tones, and they tend to have a more reddish shade, whereas animals from the central species (2n=58), which inhabits mainly dark soils including alluvial clays, terra rossa and brown rendzina and the souther species 2n=60, which occurs mainly in light soil types such as pale rendzina, sandy loams and loess, tend to have a more yellowish shade. The general appearance of specimens from 2n=58 was dark gray while that of 2n=60 specimens was light gray; 5. mole rats living in xeric environments (particularly 2n=60, but also 2n=54) are lighter than those which live in mesic environments (2n=52, 58). The results support the conclusion that pelage color of strictly subterranean mole rats is subject to selection pressures of overground predation of disharmonious types with their background soil color. The possibility that the pelage color variation and patterns also contributes to better thermoregulation while mole rats are above ground is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380062
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  • 6
    Electronic Resource
    Electronic Resource
    Adaptive variation in structure and function of kidneys of speciating subterranean mole rats (1989)
    Springer
    Oecologia 79 (1989), S. 366-371 
    Details
    ISSN: 1432-1939
    Keywords: Adaptation ; Speciation ; Urine ; Kidney ; Spalax ehrenbergi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We report on kidney structure and function in subterranean mammals of four chromosomal species (2n=52, 54, 58 and 60) belonging to the Spalax ehrenbergi superspecies, in relation to their speciation and adaptive radiation from mesic (2n=52) to xeric (2n=60) environments in Israel. Structural variables measured involved: (1) Relative Medullary Thickness, (RMT); (2) Relative Kidney Weight. (RKW); and (3) Percentage of Kidney out of Body Weight (PKW). Functional variables involved: (i) Urine Solid Concentration, (USC); and (ii) Urine Osmotic Concentration (UOC). The results for chromosomal species 2n=52, 54, 58 and 60 indicated nonsignificant increase southward for RMT, but displayed significant increase along the same transect for RKW, PKW, and USC. The UOC was significantly lower in mesic 2n=52 as compared to the other three species when experimental animals were fed in the laboratory on regular carrot food. However, protein stress food (soybean) and salt stress of 0.45 mol NaCl, caused significant, three and a half fold increase of UOC in 2n=52, 54 and 58; but four and a half fold increase in 2n=60, significantly higher than in the other three species. We conclude that both structurally and functionally, the kidneys differentiated adaptively during the Pleistocene evolution of S. ehrenbergi in Israel, in accordance with aridity stress and halophyte food resources towards the desert. Nevertheless, Spalax generally shows clear upper limits in kidney structural and functional capacities, preventing it from colonizing the true desert, south of the 100 mm isohyete.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384316
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  • 7
    Electronic Resource
    Electronic Resource
    Competitive exclusion between insular Lacerta species (Sauria, Lacertidae) (1972)
    Springer
    Oecologia 10 (1972), S. 183-190 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Competetive exclusion between Lacerta sicula and L. melisellensis characterizes the small islands of the Adriatic Sea. In 1958 and 1959 M. Radovanovié introduced Lacerta sicula or Lacerta melisellensis onto islands exclusively occupied by the other species. During the summer of 1971 follow-up observations were made on three of these islands, two of which completely lacked representatives of the introduced species. On the third island, the introduced species appears to be replacing the native form. Minor habitat differences permit coexistence, however the situation is dynamic and probably not at equilibrium. A reciprocal introduction involving the two species on the islands of Pod Kopiŝte and Pod Mrĉaru is announced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00347990
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  • 8
    Electronic Resource
    Electronic Resource
    Molecular Evolution of Cytochrome b of Subterranean Mole Rats, Spalax ehrenbergi Superspecies, in Israel (1999)
    Springer
    Journal of molecular evolution 49 (1999), S. 215-226 
    Details
    ISSN: 1432-1432
    Keywords: Key words: Speciation — Adaptation — Subterranean mammals — Molecular evolution — Mitochondrial cytochrome b— Transition–transversion ratio — Codon usage — DNA compositional bias
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. We describe the molecular evolution of cytochrome b of blind subterranean mole rats. We examined 12 individuals for nucleotide differences in the region of 402 base pairs of mitochondrial cytochrome b. Each individual represents a different population from the entire ecological and speciational range of the four chromosomal species in Israel (2n= 52, 54, 58, and 60) belonging to the Spalax ehrenbergi superspecies. Our results indicate the following. (i) There are seven first-position transitional differences, compared to 34 variable third positions, with no observed second-position substitutions. (ii) A maximum of four amino acids differences occurs across the range. (iii) Within-species diversity increases southward. Only 1 autoapomorphic substitution characterizes either 2n= 52 or 2n= 54, but 6–11 substitutions characterize 2n= 58, and 9–13 substitutions characterize 2n= 60. (iv) Both parsimony and maximum-likelihood trees suggest two monophyletic groups: (a) 2n= 52 and 54, and (b) 2n= 58 and 60, as identified earlier by other protein and DNA markers. (v) Mitochondrial cytochrome b heterogeneity is significantly correlated with climatic factors (rainfall) and biotic factors (body size and allozymes). We hypothesize that two selective regimes direct cytochrome b evolution in the S. ehrenbergi superspecies: (i) purifying selection in the flooded, mesic, hypoxic northern range of 2n= 52 and 54 and (ii) diversifying selection in the climatically spatiotemporal, xeric, and variable southern range of 2n= 58 and 60. Thus, the molecular evolution of mitochondrial cytochrome b in S. ehrenbergi is explicable by opposite selective stresses across the range of S. ehrenbergi in Israel, associated with the ecological adaptive radiation of the complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006544
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  • 9
    Electronic Resource
    Electronic Resource
    Association of alleles at esterase loci in wild barley Hordeum spontaneum L. (1977)
    [s.l.] : Nature Publishing Group
    Nature 268 (1977), S. 430-431 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Cultivated barley (Hordeum vulgare) is polymorphic for four esterase loci. Three of the loci, denoted Est A, Est B and Est C are tightly linked C#-0.0023-M(^-0.0048-^C) and a fourth, Est D recombines independently4. In composite cross V, Allard and co-workers have described changes in gene ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/268430a0
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  • 10
    Electronic Resource
    Electronic Resource
    Test of Selection and Neutrality in Natural Populations (1973)
    [s.l.] : Nature Publishing Group
    Nature 244 (1973), S. 573-575 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A test of the theory of selective neutrality of polymorphisms has recently been suggested by Lewontin and Krakawer3, on the basis of an idea first introduced by Cavalli-Sforza4 in analysing human evolution. The method is based on the contrasting effects of natural selection and the breeding ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/244573a0
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