Collections of D. melanogaster from Japanese populations were analyzed for enzyme and chromosomal polymorphisms. Allelic frequencies at the Adh and αGpd loci were compared with polymorphic inversion (In(2L)B, In(2R)C) frequencies in the second chromosome. There was a significant positive correlation between the frequencies of AdhS and In(2L)B, caused by linkage. On the other hand, inversion-free cage populations maintained in the laboratory for a long time showed considerably larger variation in the frequencies of these enzyme alleles, which seem very likely to be a consequence of random drift. Two fitness components of these enzyme and chromosomal variants were measured in two different environmental conditions; neither of the two loci showed heterozygote superiority in viability or productivity, while the inversion heterozygotes showed a superior productivity compared to the corresponding homozygotes in the fluctuating environment. These findings are compatible with the hypothesis that polymorphic isozyme genes are maintained by random drift of neutral genes in natural populations, and that association with linked inversions is a historical accident.
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机译:分析了日本人群中黑腹果蝇的酶和染色体多态性。将Adh和αGpd位点的等位基因频率与第二条染色体中的多态性倒置(In(2L)B,In(2R)C)频率进行比较。连接引起的Adh S sup>和In(2L)B的频率之间存在显着的正相关。另一方面,在实验室中长期保持的无反转笼种群显示这些酶等位基因的频率变化相当大,这似乎很可能是随机漂移的结果。在两种不同的环境条件下测量了这些酶和染色体变体的两个适应性成分。在波动的环境中,这两个基因座均未显示出杂合子在生存力或生产力上的优越性,而倒位杂合子与相应的纯合子相比却显示出更高的生产力。这些发现与以下假设相符:多态同工酶基因通过自然种群中的中性基因的随机漂移而得以维持,并且与连锁倒转的关联是历史性的偶然。
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