Genic VERSUS Chromosomal Variation in Natural Populations of DROSOPHILA SUBOBSCURA

AUTOR(ES)

Zouros, E.

RESUMO

Gametic frequencies in one mainland and one island population of D. subobscura were obtained by means of extracting wild chromosomes and subsequently analyzing them for inversions and allozymes. The high degree of cytological heterogeneity which characterizes these populations is not reflected in the genetic data. Two cases of non-random association were observed among eighteen pair-wise comparisons involving gene alleles and inversions to which the locus is linked. In both cases exchange of alleles at the locus is completely suppressed by the inversions. Four cases of linkage disequilibrium were detected among eighteen pairs of loci; two of them could best be explained as transient associations generated by random drift. The results suggest that disequilibria among enzyme loci are not widespread in natural populations—Populations with a lower degree of chromosomal variation are genetically as variable as populations with a higher degree of chromosomal variation. This observation does not support the hypothesis that selection in marginal homokaryotypic populations is for specialized homozygous genotypes.

Documentos Relacionados

• Genetics of Natural Populations. II. Genic Variation in Populations of Drosophila Pseudoobscura Inhabiting Isolated Mountain Ranges
• Enzyme Variability in the DROSOPHILA WILLISTONI Group. IV. Genic Variation in Natural Populations of DROSOPHILA WILLISTONI
• A Molecular Approach to the Study of Genic Heterozygosity in Natural Populations IV. Patterns of Genic Variation in Central, Marginal and Isolated Populations of DROSOPHILA PSEUDOOBSCURA
• GENIC VARIATION IN A NATURAL POPULATION OF Drosophila persimilis*
• Colonization of America by Drosophila subobscura: Experiment in natural populations that supports the adaptive role of chromosomal-inversion polymorphism