The fertility effects of pericentric inversions in Drosophila melanogaster.
The fertility effects of pericentric inversions in Drosophila melanogaster.
复制标题
果蝇核周倒位的生育效应。
DOI：
10.1093/genetics/134.2.487
复制
发表时间：
1993
期刊：
影响因子：
3.3
通讯作者：
Sniegowski,P
中科院分区：
文献类型：
--
作者：
Coyne,JA;Meyers,W;Crittenden,AP;Sniegowski,P
臂间倒位的杂合子被认为是半不育的，因为在倒位区域的重组产生非整倍体配子。因此，新出现的臂间倒位应该通过自然选择迅速从种群中消除。这种倒位的偶然多态性及其在密切相关物种中的固定性支持了这样一种观点，即在非常小的种群中，遗传漂变可以克服野生环境中的自然选择。研究了7条第二染色体和30条第三染色体臂间倒位对异核型果蝇雌性生育力的影响。令人惊讶的是，在许多情况下，生育率并没有显著降低，即使倒置相当大。几乎可以肯定的是，这种缺乏弱显性的现象是由于倒位杂合子中的重组受到抑制，这是以前在果蝇中观察到的现象。在第三染色体倒位的大样本中，显性不足的程度更多地取决于断点的位置，而不是倒位的长度。这些位置的分析表明，这条染色体有一对“敏感的网站”附近的细胞分裂68和92：这些网站似乎减少重组的杂合倒位的断点附近。在第二条染色体上的31和49分裂附近也可能有“敏感位点”。这些位点在启动突触中可能是重要的。由于许多臂间倒位并不降低杂合子的生育力，我们得出结论，观察到的固定或多态性，这种重排在自然界中并不意味着在很小的群体遗传漂变。
Heterozygotes for pericentric inversions are expected to be semisterile because recombination in the inverted region produces aneuploid gametes. Newly arising pericentric inversions should therefore be quickly eliminated from populations by natural selection. The occasional polymorphism for such inversions and their fixation among closely related species have supported the idea that genetic drift in very small populations can overcome natural selection in the wild. We studied the effect of 7 second-chromosome and 30 third-chromosome pericentric inversions on the fertility of heterokaryotypic Drosophila melanogaster females. Surprisingly, fertility was not significantly reduced in many cases, even when the inversion was quite large. This lack of underdominance is almost certainly due to suppressed recombination in inversion heterozygotes, a phenomenon previously observed in Drosophila. In the large sample of third-chromosome inversions, the degree of underdominance depends far more on the position of breakpoints than on the inversion's length. Analysis of these positions shows that this chromosome has a pair of "sensitive sites" near cytological divisions 68 and 92: these sites appear to reduce recombination in a heterozygous inversion whose breakpoints are nearby. There may also be "sensitive sites" near divisions 31 and 49 on the second chromosome. Such sites may be important in initiating synapsis. Because many pericentric inversions do not reduce the fertility of heterozygotes, we conclude that the observed fixation or polymorphism of such rearrangements in nature does not imply genetic drift in very small populations.