Chenoweth Stephen F, Rundle Howard D, Blows Mark W
School of Integrative Biology, University of Queensland, St. Lucia, Queensland 4072, Australia.
Am Nat. 2008 Jan;171(1):22-34. doi: 10.1086/523946.
The evolution of sexual dimorphism involves an interaction between sex-specific selection and a breakdown of genetic constraints that arise because the two sexes share a genome. We examined genetic constraints and the effect of sex-specific selection on a suite of sexually dimorphic display traits in Drosophila serrata. Sexual dimorphism varied among nine natural populations covering a substantial portion of the species range. Quantitative genetic analyses showed that intersexual genetic correlations were high because of autosomal genetic variance but that the inclusion of X-linked effects reduced genetic correlations substantially, indicating that sex linkage may be an important mechanism by which intersexual genetic constraints are reduced in this species. We then explored the potential for both natural and sexual selection to influence these traits, using a 12-generation laboratory experiment in which we altered the opportunities for each process as flies adapted to a novel environment. Sexual dimorphism evolved, with natural selection reducing sexual dimorphism, whereas sexual selection tended to increase it overall. To this extent, our results are consistent with the hypothesis that sexual selection favors evolutionary divergence of the sexes. However, sex-specific responses to natural and sexual selection contrasted with the classic model because sexual selection affected females rather than males.
两性异形的进化涉及性别特异性选择与遗传限制的瓦解之间的相互作用，这种遗传限制的产生是因为两性共享一个基因组。我们研究了遗传限制以及性别特异性选择对锯角果蝇一系列两性异形的展示性状的影响。两性异形在涵盖该物种大部分分布范围的九个自然种群中有所不同。数量遗传学分析表明，由于常染色体遗传变异，两性之间的遗传相关性很高，但纳入X连锁效应后，遗传相关性大幅降低，这表明性连锁可能是该物种减少两性之间遗传限制的一个重要机制。然后，我们通过一项12代的实验室实验，探索了自然选择和性选择影响这些性状的可能性，在实验中，随着果蝇适应新环境，我们改变了每个过程的机会。两性异形发生了进化，自然选择减少了两性异形，而性选择总体上倾向于增加两性异形。在这个程度上，我们的结果与性选择有利于两性进化分歧的假设一致。然而，对自然选择和性选择的性别特异性反应与经典模型不同，因为性选择影响的是雌性而非雄性。
