On Coadaptation in Drosophila
On Coadaptation in Drosophila
复制标题
果蝇的相互适应
作者：
B. Wallace
不同基因排列所携带的基因复合体在一个群体内的共适应取决于其基因内容的完整性。在上面的描述中，某些逆转录组合——三联体——通过交叉促进基因从一种排列到另一种排列的序列转移，从而破坏了这种完整性。由于一个种群的不同倒位通常是共同适应的，因此任何一个三和弦的三种倒位中，种群最多应具有两种。总的来说，来自罗布斯塔和伪罗布斯塔种群的数据支持这一假设；在任何一个地区，每个三和弦中通常都没有或很少有一个成员。不属于三位一体的三种倒位不应该被选择反对，并且，与假设一致，三种这样的倒位经常出现在高频率的种群中。我们得出的结论是，在决定群体内反转频率方面，共同适应往往超过非整倍性作为一种选择力量。本文还讨论了三联体在倒转的地理分布和物种形成中的可能作用。
The coadaptation of the gene complexes carried by different gene arrangements within a population depends upon the integrity of the genic contents of the inverted segments. Certain combinations of inversions-triads, in the above account-destroy this integrity by facilitating serial transfer of genes from one arrangement to another by crossing-over. Since the different inversions of a population are generally coadapted, populations should possess with high frequency, at most, two of the three inversions of any one triad. In general, the data from populations of D. robusta and D. pseudoobscura support this hypothesis; one member of each triad is usually absent or rare within any one locality. Three inversions that are not members of a triad should not be opposed by selection and, in agreement with the hypothesis, three such inversions are frequently present in populations with high frequency. We conclude that coadaptation frequently outweighs aneuploidy as a selective force in determining inversion frequencies within populations. The possible role of triads in the geographical distribution of inversions and in speciation are also discussed.