Data from: The genetic variance but not the genetic covariance of life-history traits changes towards the north in a time-constrained insect

Seasonal time constraints are usually stronger at higher than lower latitudes and can exert strong selection on life history traits and the correlations among these traits. To predict the response of life history traits to environmental change along a latitudinal gradient, information must be obtained about genetic variance in traits and also genetic correlation between traits, i.e., the genetic variance-covariance matrix, G. Here, we estimated G for key life history traits in an obligate univoltine damselfly that faces seasonal time constraints. We exposed populations to simulated native temperatures and photoperiods and common garden environmental conditions in a laboratory setup. Despite differences in genetic variance in these traits between populations (lower variance at northern latitudes), there was no evidence for latitude-specific covariance of the life history traits. At simulated native conditions, all populations showed strong genetic and phenotypic correlations between traits that shaped growth and development. The variance-covariance matrix changed considerably when populations were exposed to common garden conditions compared with the simulated natural conditions, showing the importance of environmentally induced changes in multivariate genetic structure. Our results highlight the importance of estimating variance-covariance matrixes in environments that mimic selection pressures and not only trait variances or mean trait values in common garden conditions for understanding the trait evolution across populations and environments.季节性时间约束在高纬度地区通常较低纬度地区更强，且会对生活史性状及其间的相关性施加强烈的选择压力。为预测生活史性状沿纬度梯度对环境变化的响应，需获取性状的遗传方差以及性状间的遗传相关性信息，即遗传方差-协方差矩阵（G矩阵）。本研究针对一种面临季节性时间约束的专性一化性豆娘（obligate univoltine damselfly），估算了其关键生活史性状的G矩阵。我们在实验室实验设置中，将种群分别置于模拟的原生温度、光周期条件以及同质园（common garden）环境条件下进行处理。尽管不同种群间的性状遗传方差存在差异（高纬度种群的方差更低），但未发现生活史性状的协方差存在纬度特异性的证据。在模拟的原生条件下，所有种群均表现出显著的性状间遗传与表型相关性，这些相关性塑造了个体的生长与发育过程。相较于模拟的自然条件，当种群处于同质园环境时，其方差-协方差矩阵发生了显著改变，这表明环境诱导的多变量遗传结构变化具有重要意义。本研究结果强调，在理解种群与环境间的性状演化规律时，需在模拟选择压力的环境中估算方差-协方差矩阵，而非仅在同质园条件下测定性状方差或平均性状值。