Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
Evolution. 2010 Sep;64(9):2601-13. doi: 10.1111/j.1558-5646.2010.01023.x.
The G-matrix occupies an important position in evolutionary biology both as a summary of the inheritance of quantitative traits and as an ingredient in predicting how those traits will respond to selection and drift. Consequently, the stability of G has an important bearing on the accuracy of predicted evolutionary trajectories. Furthermore, G should evolve in response to stable features of the adaptive landscape and their trajectories through time. Although the stability and evolution of G might be predicted from knowledge of selection in natural populations, most empirical comparisons of G-matrices have been made in the absence of such a priori predictions. We present a theoretical argument that within-sex G-matrices should be more stable than between-sex B-matrices because they are more powerfully exposed to multivariate stabilizing selection. We tested this conjecture by comparing estimates of B- and within-sex G-matrices among three populations of the garter snake Thamnophis elegans. Matrix comparisons using Flury's hierarchical approach revealed that within-sex G-matrices had four principal components in common (full CPC), whereas B-matrices had only a single principal component in common and eigenvalues that were more variable among populations. These results suggest that within-sex G is more stable than B, as predicted by our theoretical argument.
G 矩阵在进化生物学中占有重要地位，既是数量性状遗传的总结，也是预测这些性状如何对选择和漂变做出反应的要素。因此，G 的稳定性对预测进化轨迹的准确性有重要影响。此外，G 应该响应适应性景观的稳定特征及其随时间的轨迹而进化。尽管可以根据自然种群中的选择知识来预测 G 矩阵的稳定性和进化，但大多数 G 矩阵的经验比较都是在没有这种先验预测的情况下进行的。我们提出了一个理论观点，即同性别 G 矩阵应该比性别间 B 矩阵更稳定，因为它们更受到多变量稳定选择的影响。我们通过比较三种彩蛇 Thamnophis elegans 种群的 B-矩阵和同性别 G 矩阵来检验这一假设。使用 Flury 分层方法进行的矩阵比较表明，同性别 G 矩阵有四个共同的主要成分（完全 CPC），而 B 矩阵只有一个共同的主要成分，且特征值在种群间的变异性更大。这些结果表明，正如我们的理论观点所预测的那样，同性别 G 比性别间 B 更稳定。
