Data from: The evolutionary stability of cross-sex, cross-trait genetic covariances

Although knowledge of the selective agents behind the evolution of sexual dimorphism has advanced considerably in recent years, we still lack a clear understanding of the evolutionary durability of cross-sex genetic covariances that often constrain its evolution. We tested the relative stability of cross-sex genetic covariances for a suite of homologous contact pheromones of the fruit fly Drosophila serrata, along a latitudinal gradient that these traits have diverged in mean. Using a Bayesian framework, which allowed us to account for uncertainty in all parameter estimates, we compared divergence in the total amounts and orientations of genetic variance across populations, finding divergence in orientation but not total variance. We then statistically compared orientation divergence of within-sex (G) to cross-sex (B) covariance matrices. In line with a previous theoretical prediction, we find that the cross-sex covariance matrix, B, is more variable than either male or female within-sex covariance matrix. Decomposition of B matrices into their symmetrical and non-symmetrical components revealed that instability is linked to the degree of asymmetry. We also find that the degree of asymmetry correlates with latitude suggesting a role for spatially varying natural selection in shaping genetic constraints on the evolution of sexual dimorphism.

尽管近年来学界对性二型性（sexual dimorphism）演化背后的选择动因的认知已有显著进展，但我们仍未明确理解常对其演化形成约束的跨性遗传协方差（cross-sex genetic covariances）的演化持久性。我们针对 Serrata果蝇（Drosophila serrata）的一系列同源接触信息素（contact pheromones），沿这些性状均值发生分化的纬度梯度，检验了跨性遗传协方差的相对稳定性。我们采用贝叶斯框架（Bayesian framework），该方法可让我们考量所有参数估计值的不确定性，比较了不同种群间遗传方差总量与取向的分化情况，结果发现取向存在分化，但遗传方差总量并无差异。随后我们通过统计学方法比较了同性别（G）与跨性别（B）协方差矩阵（covariance matrices）的取向分化程度。与此前的理论预测一致，我们发现跨性别协方差矩阵B的变异程度高于雄性或雌性的同性别协方差矩阵。对B矩阵的对称与非对称分量进行分解后发现，其不稳定性与不对称程度相关。我们还发现不对称程度与纬度存在关联，这表明空间变化的自然选择在塑造性二型性演化的遗传约束方面发挥了作用。