Department of Natural History, Royal Ontario Museum, Toronto, Ontario, Canada, M5S 2C6.
Department of Ecology and Evolutionary Biology, University of Toronto, Ontario, Canada, M5S 3B2.
Evolution. 2015 Jun;69(6):1597-1609. doi: 10.1111/evo.12680. Epub 2015 Jun 8.
Sexual dimorphism is a consequence of both sex-specific selection and potential constraints imposed by a shared genetic architecture underlying sexually homologous traits. However, genetic architecture is expected to evolve to mitigate these constraints, allowing the sexes to approach their respective optimal mean phenotype. In addition, sex-specific selection is expected to generate sexual dimorphism of trait covariance structure (e.g., the phenotypic covariance matrix, P), but previous empirical work has not fully addressed this prediction. We compared patterns of phenotypic divergence, for three traits in seven taxa in the insect genus Phymata (Reduviidae), to ask whether sexual dimorphism in P is common and whether its magnitude relates to the extent of sexual dimorphism in trait means. We found that sexual dimorphism in both mean and covariance structure was pervasive but also that the multivariate distance between sex-specific means was correlated with sex differences in the leading eigenvector of P, while accounting for uncertainty in phylogenetic relationships. Collectively, our findings suggest that sexual dimorphism in covariance structure may be a common but underappreciated feature of dioecious populations.
性二型性是由特定性别选择和潜在约束共同作用的结果，这些约束是由性同源特征所共同的遗传结构所施加的。然而，遗传结构预计会进化以减轻这些约束，使两性能够接近各自的最佳平均表型。此外，特定性别的选择预计会产生性状协方差结构的性二型性（例如，表型协方差矩阵，P），但以前的实证工作并未完全解决这一预测。我们比较了昆虫属 Phymata （Reduviidae）中七个分类群的三个特征的表型差异模式，以询问 P 中的性二型性是否普遍存在，以及其幅度是否与性状均值的性二型性程度有关。我们发现，无论是在均值还是在协方差结构方面，性二型性都普遍存在，但特定性别均值之间的多元距离与 P 的主特征向量的性别差异相关，同时考虑了系统发育关系的不确定性。总的来说，我们的研究结果表明，协方差结构的性二型性可能是雌雄异株群体的一个常见但被低估的特征。
