Stevison L S, Counterman B A, Noor M A F
Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
J Hered. 2004 Mar-Apr;95(2):114-8. doi: 10.1093/jhered/esh027.
In Drosophila melanogaster and Drosophila simulans, positive Darwinian selection drives high rates of evolution of male reproductive genes, and accessory gland proteins (Acps) in particular. Here, we tested whether 13 X-linked male-specific genes, 4 Acps and 9 non-Acps, are under selective forces in the Drosophila pseudoobscura species group, much as those in the D. melanogaster group. We observed a statistically significant correlation in relative rates of nonsynonymous evolution between the two species groups tested. One Acp examined had a higher rate of nonsynonymous substitution than predicted by a neutral model in both species groups, suggesting its divergence was driven by positive Darwinian selection. To further test for the signature of selection, we examined polymorphism of three Acps within D. pseudoobscura. From this test, no Acp individually bore the signature of positive selection, but the 3 Acps together possessed an excess of nonsynonymous differences between species, relative to polymorphism within species. We conclude that faster evolution of Acps in the D. pseudoobscura group appears to be driven by positive selection, as previously suggested in the D. melanogaster group.
在黑腹果蝇和拟暗果蝇中，正向达尔文选择推动雄性生殖基因，尤其是附属腺蛋白（Acps）的高进化速率。在此，我们测试了13个X连锁雄性特异性基因、4个Acps和9个非Acps在果蝇伪暗果蝇物种组中是否受到选择压力，就像在黑腹果蝇组中那样。我们观察到所测试的两个物种组之间非同义进化的相对速率存在统计学上显著的相关性。在两个物种组中，所检测的一个Acp的非同义替换率高于中性模型预测的速率，表明其分化是由正向达尔文选择驱动的。为了进一步测试选择的特征，我们检测了伪暗果蝇体内三个Acps的多态性。从这个测试来看，没有单个Acp呈现出正选择的特征，但相对于物种内的多态性，这3个Acps共同拥有物种间过量的非同义差异。我们得出结论，如先前在黑腹果蝇组中所表明的那样，伪暗果蝇组中Acps的更快进化似乎是由正选择驱动的。
