Department of Chemistry and Bioscience, Aalborg University, DK-9220, Aalborg East, Denmark.
Department of Biology, Lund University, Lund, SE-22362, Sweden.
Evolution. 2019 Aug;73(8):1672-1678. doi: 10.1111/evo.13762. Epub 2019 Jun 19.
Genetic correlations for a trait across environments are predicted to decrease as environments diverge. However, estimates of genetic correlations from natural populations are typically defined across a limited environmental range and prone to very large standard errors, making it difficult to test this prediction. We address the importance of environmental distance on genetic correlations by employing data from domestic cattle in which abundant and accurate estimates are available from a wide range of environments. Three production traits related to milk yield show a clear decrease in genetic correlations with increasing environmental divergence. This pattern was also evident for growth traits and other yield traits but not for traits related to reproduction, morphology, physiology, or disease. We suspect that this reflects weaker selection on these latter trait classes compared to production traits, or alternatively the effects of selection are constrained by unfavorable genetic correlations between traits. The results support the notion that traits that historically have been under strong directional selection in a small range of frequently encountered environments will evolve high genetic correlations across these environments, while exposure to uncommon (and dissimilar) environments lead to a reranking of gene effects and a decrease in genetic correlations across environments.
跨环境性状的遗传相关预计会随着环境的差异而降低。然而，来自自然种群的遗传相关估计通常是在有限的环境范围内定义的，并且容易受到非常大的标准误差的影响，因此很难验证这一预测。我们通过利用来自家养牛的数据来解决环境距离对遗传相关的重要性，这些数据来自广泛的环境，具有丰富和准确的估计。与产奶量相关的三个生产性状随着环境差异的增加，遗传相关明显降低。这种模式在生长性状和其他产量性状中也很明显，但在与繁殖、形态、生理或疾病相关的性状中则不然。我们怀疑这反映了与生产性状相比，对这些后者性状类别的选择较弱，或者选择的效果受到性状之间不利遗传相关的限制。研究结果支持了这样一种观点，即在一小部分经常遇到的环境中经历了强烈定向选择的历史性状，将在这些环境中表现出较高的遗传相关性，而暴露于不常见（和不同）的环境中会导致基因效应的重新排序，并降低环境之间的遗传相关性。
