School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia.
Evolution. 2018 Jun;72(6):1317-1327. doi: 10.1111/evo.13494. Epub 2018 May 14.
Natural selection varies widely among locations of a species' range, favoring population divergence and adaptation to local environmental conditions. Selection also differs between females and males, favoring the evolution of sexual dimorphism. Both forms of within-species evolutionary diversification are widely studied, though largely in isolation, and it remains unclear whether environmental variability typically generates similar or distinct patterns of selection on each sex. Studies of sex-specific local adaptation are also challenging because they must account for genetic correlations between female and male traits, which may lead to correlated patterns of trait divergence between sexes, whether or not local selection patterns are aligned or differ between the sexes. We quantified sex-specific divergence in five clinally variable traits in Drosophila melanogaster that individually vary in their magnitude of cross-sex genetic correlation (i.e., from moderate to strongly positive). In all five traits, we observed parallel male and female clines, regardless of the magnitude of their genetic correlation. These patterns imply that parallel spatial divergence of female and male traits is a reflection of sexually concordant directional selection imposed by local environmental conditions. In such contexts, genetic correlations between the sexes promote, rather than constrain, local adaptation to a spatially variable environment.
自然选择在物种分布范围的不同地点差异很大，有利于种群的分歧和对当地环境条件的适应。选择也在雌性和雄性之间存在差异，有利于性二态性的进化。这两种形式的种内进化多样性都得到了广泛的研究，尽管很大程度上是孤立的，目前还不清楚环境变异性通常是否会在每一个性别上产生相似或不同的选择模式。对性别特异性局部适应的研究也具有挑战性，因为它们必须考虑雌性和雄性特征之间的遗传相关性，这可能导致性别之间特征分歧的相关模式，无论性别之间的局部选择模式是否一致或不同。我们量化了黑腹果蝇中五个沿地理梯度变化的特征的性别特异性分歧，这些特征在跨性别遗传相关性的大小上各不相同（即从中等到强烈正相关）。在所有五个特征中，我们观察到了平行的雄性和雌性渐变，无论它们的遗传相关性大小如何。这些模式表明，雌性和雄性特征的平行空间分歧反映了由当地环境条件施加的性一致的定向选择。在这种情况下，性别之间的遗传相关性促进了对空间变化环境的局部适应，而不是限制了它。
