Evidence for Extensive Genetic Differentiation between the Sex-Ratio and the Standard Arrangement of DROSOPHILA PSEUDOOBSCURA and D. PERSIMILIS and Identification of Hybrid Sterility Factors.
Evidence for Extensive Genetic Differentiation between the Sex-Ratio and the Standard Arrangement of DROSOPHILA PSEUDOOBSCURA and D. PERSIMILIS and Identification of Hybrid Sterility Factors.
复制标题
果蝇 PSEUDOOBSCURA 和 D. PERSIMILIS 的性别比和标准排列之间广泛遗传分化的证据以及杂种不育因子的鉴定。
作者：
Chung;A. Beckenbach
本研究涉及性比倒位中紧密连锁的性比基因。利用果蝇（Drosophila persimilis）的性比染色体[SR（B）]与果蝇（Drosophila persimilis）的标准染色体具有同源序列的特点，对果蝇（Drosophila persimilis）的性比染色体进行了研究。pseudobscura [ST（A）]，我们进行了两个相互渐渗实验。SR（B）或ST（A）的单个片段渗入D. pseudobscura或D. persimilis，分别。对具有杂交SR（B）-ST（A）X染色体和来自两个物种之一的遗传背景的雄性进行了生育力和性比表达测试。结果发现，在减数分裂驱动基因方面，性比染色体与标准染色体有很大的不同。由于这些基因的重组导致性比表达的完全丧失，这一发现有力地支持了基因共适应的假设。在这种情况下，相互适应是优先传播的优势。根据这一发现，性比系统在这两个兄弟物种的进化进行了讨论。渐渗实验也产生了关于杂种不育的信息。在互作渐渗中，不育性互作被认为是“不对称的”。“从交配后生殖隔离进化的角度来看，这种不对称是完全可以预料到的。
This study deals with sex-ratio genes tightly linked within the Sex-Ratio inversion. By taking advantage of the fact that the Sex-Ratio chromosome of Drosophila persimilis [SR(B)] is homosequential to the Standard chromosome of D. pseudoobscura [ST(A)], we carried out two reciprocal introgression experiments. Individual segments of SR(B) or ST(A) were introgressed into the genome of D. pseudoobscura or D. persimilis, respectively. Males possessing a hybrid SR(B)-ST(A) X chromosome and a genetic background derived from either of the two species were tested for fertility and sex-ratio expression.-It was found that, in terms of the meiotic drive genes, the Sex-Ratio chromosome differs extensively from the Standard chromosome. Because recombinations of these genes result in a complete loss of sex-ratio expression, this finding lends strong support to the hypothesis of gene coadaptation. Coadaptation, in this context, is the advantage of being transmitted preferentially. In light of this finding, the evolution of the sex-ratio system in these two sibling species is discussed.-Introgression experiments also yielded information about hybrid sterility. With reciprocal introgression, sterility interactions were found to be "asymmetric." The asymmetry is fully expected from the viewpoint of evolution of postmating reproductive isolation.