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  • 1980-1984  (6)
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Materialart
Erscheinungszeitraum
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Satellite DNA sequences and reproductive isolation in theDrosophila willistoni group (1980)
    Springer
    Cellular and molecular life sciences 36 (1980), S. 837-839 
    Details
    ISSN: 1420-9071
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Satellite DNAs of theDrosophila willistoni group have been analyzed by Hae III endonuclease digestion. Differences were observed between the 2 speciesD. willistoni andD. paulistorum and also between semispecies ofD. paulistorum and, to a lesser extent, between subspecies ofD. willistoni. Differences did not appear to be consistently greater between strains producing sterile hybrid males than between those producing fertile hybrids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01978600
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  • 2
    Digitale Medien
    Digitale Medien
    Wineries, drosophila, alcohol, and Adh (1980)
    Springer
    Oecologia 47 (1980), S. 141-144 
    Details
    ISSN: 1432-1939
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Previous workers (McKenzie and Parsons, 1972, 1974; McKenzie, 1974; Briscoe et al., 1975) have found anomalous distributions of species of Drosophila, of sexes of D. melanogaster, and of Adh alleles in and around wineries in Australia and Spain. Field studies in California's Sonoma Valley provide evidence that the explanations advanced for these distributions may incorrect. The anomalous distribution of species was attributed to alcohol, either as a selective agent or as a behavioral stimulus. We find a virtually identical species distribution in the absence of environmental alcohol. The anomalous sex ratio was attributedd to differential survivall of the sexes when raised on alcohol. We present crude evidence thatehe difference may simply be a behavioral response to some product of fermentation, which need not be alcohol. Finally, the allele frequency difference reported from Spain was attributed to differential adult mortality on alcohol. We do not find an allele frequency difference even when alcohol is exposed, and therefore suggest that selection is occurring in pre-adult stages.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00541790
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  • 3
    Digitale Medien
    Digitale Medien
    Genetic polymorphism: from electrophoresis to DNA sequences (1983)
    Springer
    Cellular and molecular life sciences 39 (1983), S. 813-823 
    Details
    ISSN: 1420-9071
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Recent studies indicate that the amount of protein variation undetected by electrophoresis may be reasonably small. Nevertheless, at the protein level, a typical sexually-reproducing organism may be heterozygous at 20 or more percent of the gene loci. Although the evidence is limited, it appears that at the level of the DNA nucleotide sequence every individual is heterozygous at every locus — if introns as well as exons are taken into account. The evidence available does not support the hypothesis that, at least at the protein level, the variation is adaptively neutral.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01990397
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  • 4
    Digitale Medien
    Digitale Medien
    Effects of allozyme variation on fitness components in Drosophila melanogaster (1983)
    Springer
    Genetica 62 (1983), S. 139-146 
    Details
    ISSN: 1573-6857
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have explored in Drosophila melanogaster the fitness effects of allelic variation at three enzyme loci: α Gdh, Adh, and Acph. Viability and rate of development are studied at two densities, near-optimal and competitive. No genotypic effects could be demonstrated on rate of development at either density or on viability under optimal conditions. Small but significant effects on viability appear under competitive conditions. Fecundity is measured for all nine possible mating combinations between the three female and the three male genotypes at each locus. Female genotype has important fitness consequences; heterosis exists at every locus. Male genotype also contributes to fitness, but without heterosis. There are significant interactions between female and male genotypes, so that the fecundity of a mating combination cannot be determined from the average fitnesses of the female genotype and the male genotype involved.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00116635
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  • 5
    Digitale Medien
    Digitale Medien
    Correlation between recombination frequency and fitness in Drosophila melanogaster (1981)
    Springer
    Genetica 56 (1981), S. 61-69 
    Details
    ISSN: 1573-6857
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The origin and maintenance of genetic recombination are unsettled evolutionary issues. Genetic variation affecting recombination frequency appears to be pervasive in nature, suggesting that natural selection must increase recombination frequency under some circumstances. However, theoretical arguments and experimental evidence indicate that the frequency of recombination should be reduced by natural selection. A hypothesis not previously explored is that recombination modifiers may directly affect the fitness of their carriers; rather than only indirectly (through the production of recombinant progeny) as generally assumed. We have tested this hypothesis by examining three fitness components (viability, male fertility, and female fecundity) in Drosophila melanogaster homozygous for second chromosomes isolated from a natural population. Then, we have measured the frequency of recombination in flies heterozygous for each wild second chromosome and a chromosome carrying five recessive alleles. The results indicate that genes modulating the frequency of recombination have direct effects on fitness as proposed by the hypothesis. However, the correlation between frequency of recombination and fitness is negative. Thus, the riddle of recombination remains unexplained and, in fact, more puzzling that ever.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00126931
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  • 6
    Digitale Medien
    Digitale Medien
    Continuous variation: Possible role of regulatory genes (1984)
    Springer
    Genetica 52-53 (1984), S. 1-15 
    Details
    ISSN: 1573-6857
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00121808
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