Because the sexes share a genome, traits expressed in males are usually genetically correlated with the same traits expressed in females. On short timescales, between-sex genetic correlations (rmf) for shared traits may constrain the evolution of sexual dimorphism by preventing males and females from responding independently to sex-specific selection. However, over longer timescales, rmf may evolve, thereby facilitating the evolution of dimorphism. Although it has been suggested that sexually antagonistic selection may reduce rmf, we lack a general theory for the evolution of rmf and its multivariate analog, the between-sex genetic covariance matrix (B). Here, we derive a simple analytical model for the within-generation change in B due to sex-specific directional selection. We present a single-trait example demonstrating that sex-specific directional selection may either increase or decrease between-sex genetic covariance, depending on the relative strength of selection in each sex and on the current value of rmf. Although sexually antagonistic selection can reduce between-sex covariance, it will only do so when selection is much stronger in one sex than in the other. Counterintuitively, sexually antagonistic selection that is equal in strength in the two sexes will maintain positive between-sex covariance. Selection acting in the same direction on both sexes is predicted to reduce between-sex covariance in many cases. We illustrate our model numerically using empirical measures of sex-specific selection and between-sex genetic covariance from two populations of sexually dimorphic brown anole lizards (Anolis sagrei) and discuss its importance for understanding the resolution of intralocus sexual conflict.

中文翻译：

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性别特异性选择和性别间遗传协方差的演变

因为两性共享一个基因组，男性表达的特征通常与女性表达的相同特征在遗传上相关。在短时间内，共享性状的性别间遗传相关性 (rmf) 可能通过阻止男性和女性对性别特异性选择做出独立反应来限制性别二态性的进化。然而，在更长的时间尺度上，rmf 可能会演变，从而促进二态性的演变。尽管有人提出性对抗选择可能会降低 rmf，但我们缺乏关于 rmf 及其多变量类似物的进化的一般理论，即性别间遗传协方差矩阵 (B)。在这里，我们推导出了一个简单的分析模型，用于 B 由于特定性别的方向选择而引起的代内变化。我们提出了一个单一性状的例子，证明性别特异性定向选择可能会增加或减少性别间遗传协方差，这取决于每个性别的选择的相对强度和 rmf 的当前值。尽管性对抗选择可以减少性别间的协方差，但只有在一种性别的选择比另一种性别强得多时才会这样做。与直觉相反，在两性中强度相等的性对抗选择将保持正的两性间协方差。在许多情况下，预测对两性采取相同方向的选择会减少两性之间的协方差。