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  • Digitale Medien  (8)
  • 1985-1989  (3)
  • 1970-1974  (5)
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Materialart
  • Digitale Medien  (8)
Erscheinungszeitraum
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Frequency-Dependent Selection (1974)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Ecology, Evolution, and Systematics 5 (1974), S. 115-138 
    Details
    ISSN: 0066-4162
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1146/annurev.es.05.110174.000555
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  • 2
    Digitale Medien
    Digitale Medien
    Linkage Disequilibrium in Natural Populations of Trypanosoma cruzi (Flagellate), the Agent of Chagas’ Disease (1988)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 35 (1988), S. 0 
    Details
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: . We have studied linkage disequilibrium in natural populations of Trypanosoma cruzi, the agent of Chagas’ disease, by analyzing (i) a set of 524 stocks from the whole geographical range of the parasite, characterized at four gene loci coding for enzymes; (ii) a subsample of 121 stocks characterized at 12 enzyme loci; and (iii) a subset of 386 stocks from six locations in Bolivia, characterized by four enzyme loci. Our results show that the linkage disequilibrium reaches the maximum possible value, given the observed allelic frequencies, for almost all the locus pairs. This result is most consistent with the hypothesis that genetic recombination is absent or very rare in T. cruzi natural populations. Partition of the linkage disequilibrium variance for the six Bolivian populations shows that both inter- and intrapopulation components are substantial and that the relationships among the components are DIS2 〈 DST2, and D'IS2 〈 D'ST2. These inequalities are interpreted as the result of an interplay between genetic drift, rare or absent mating, and clonal selection in generating linkage disequilibrium in T. cruzi populations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1550-7408.1988.tb04081.x
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  • 3
    Digitale Medien
    Digitale Medien
    Invalidation of Principle of Competitive Exclusion Defended (1970)
    [s.l.] : Nature Publishing Group
    Nature 227 (1970), S. 89-90 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] In the competition between species of Paramecium, P. aurelia lived predominantly in the upper layer of the liquid medium and fed mostly on bacteria, while P. bursaria lived preferentially in the bottom layer and fed on yeast. There was therefore only a slight mutual depression between the species. ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/227089b0
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  • 4
    Digitale Medien
    Digitale Medien
    Competition between strains ofDrosophila willistoni andD. pseudoobscura (1971)
    Springer
    Cellular and molecular life sciences 27 (1971), S. 343-343 
    Details
    ISSN: 1420-9071
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Resumen El resultado de la competencia entreDrosophila willistoni yD. pseudoobscura depende de la constitución genética de las estirpes que compiten y de la temperatura. A 20 °C las dos especies coexisten, lo cual indica que el principio de exclusión competitiva no es universalmente válido.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02138187
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  • 5
    Digitale Medien
    Digitale Medien
    Adaptation by natural selection in populations ofDrosophila pseudoobscura (1970)
    Springer
    Cellular and molecular life sciences 26 (1970), S. 208-208 
    Details
    ISSN: 1420-9071
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Resumen Seis poblaciones deDrosophila pseudoobscura han evolucionado, debido a la selección natural, hacia una mayor adaptación al ambiente. Durante 20 o 25 generaciones el número de individuos nacidos por unidad de comida y el tamano de la poblacion han aumentado gradualmente entre un dos y un cuatro por ciento por generaciön.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01895587
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  • 6
    Digitale Medien
    Digitale Medien
    Genetic variability in the cosmopolitan deep-water ophiuran Ophiomusium lymani (1974)
    Springer
    Marine biology 27 (1974), S. 51-57 
    Details
    ISSN: 1432-1793
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A population of the cosmopolitan deep-sea ophiuran Ophiomusium lymani was studied by gel electrophoresis, and proved to be highly variable genetically; about 53% of the 15 loci studied are polymorphic, and the average individual is heterozygous at about 17% of the loci. This is approximately the same genetic variability displayed by other species, belonging to other phyla or classes, from the same deep-sea trawl. A similarly high level of genetic variation occurs in deep-sea organisms in general, and in a shallow-water tropical species. Both the deep-sea and the tropics are trophically stable environments. On the other hand, low genetic variabilities have been found in marine species from trophically unstable environments. These data suggest that any phylogenetic effects on genetic variability are secondary, and that the trophic regime may be of major importance in determining genetic strategies of adaptation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00394760
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  • 7
    Digitale Medien
    Digitale Medien
    Genetic variation for rate of development in natural populations of Drosophila melanogaster (1986)
    Springer
    Genetica 71 (1986), S. 123-132 
    Details
    ISSN: 1573-6857
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have sampled wild chromosomes from two natural populations of Drosophila melanogaster and obtained flies fully homozygous for the second chromosome, the third chromosome, or both, as well as flies heterozygous for one or both wild chromosomes and balancer chromosomes. Rate of embryogenesis (egg laying to larval hatching) and rate of development from egg to adult are measured, by classifying the individuals into fast, intermediate, and slow developmental classes. The experiments indicate that variation for rate of embryogenesis and for rate of egg-to-adult development is plentiful in the natural populations. Various hypotheses are enunciated to account for the small range of phenotypic variation observed in wild-type individuals with respect to the two parameters (embryogenesis and egg-to-adult development) and for the difficulty in changing the mean rates by artificial selection. Appropriate experiments may decide among the hypotheses, helping us to understand the genetic control of rate of ontogenesis, which is an important fitness component.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00058695
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  • 8
    Digitale Medien
    Digitale Medien
    Intra- and intergenotypic competition in Drosophila melanogaster: effects of density on larval survival and rate of development (1986)
    Springer
    Genetica 70 (1986), S. 59-67 
    Details
    ISSN: 1573-6857
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have examined the effects of density and frequency in the larval competition of Drosophila melanogaster by measuring three fitness components: viability (V), mean development time (MDT) and a combination of these two (E). We have detected (contrary to most published results) non-linear effects of density in single-genotype cultures; in addition, different functions are required to describe the density effects below and above the optimal density. Frequency has also non-linear effects in the two-genotype cultures. Only one polymorphic equilibrium frequency, which is stable, occurs with respect to V; but two polymorphic equilibria, one stable and one unstable, exist with respect to E. The responses in single-genotype cultures do not allow one to predict the outcome of the competition in two-genotype cultures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00123215
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