Robinson Matthew R, Wilson Alastair J, Pilkington Jill G, Clutton-Brock Tim H, Pemberton Josephine M, Kruuk Loeske E B
Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
Genetics. 2009 Apr;181(4):1639-48. doi: 10.1534/genetics.108.086801. Epub 2009 Feb 9.
This work demonstrates that environmental conditions experienced by individuals can shape their development and affect the stability of genetic associations. The implication of this observation is that the environmental response may influence the evolution of traits in the wild. Here, we examined how the genetic architecture of a suite of sexually dimorphic traits changed as a function of environmental conditions in an unmanaged population of Soay sheep (Ovis aries) on the island of Hirta, St. Kilda, northwest Scotland. We examined the stability of phenotypic, genetic, and environmental (residual) covariance in males during the first year of life between horn length, body weight, and parasite load in environments of different quality. We then examined the same covariance structures across environments within and between the adult sexes. We found significant genotype-by-environment interactions for lamb male body weight and parasite load, leading to a change in the genetic correlation among environments. Horn length was genetically correlated with body weight in males but not females and the genetic correlation among traits within and between the sexes was dependent upon the environmental conditions experienced during adulthood. Genetic correlations were smaller in more favorable environmental conditions, suggesting that in good environments, loci are expressed that have sex-specific effects. The reduction in genetic correlation between the sexes may allow independent evolutionary trajectories for each sex. This study demonstrates that the genetic architecture of traits is not stable under temporally varying environments and highlights the fact that evolutionary processes may depend largely upon ecological conditions.
这项研究表明，个体所经历的环境条件能够塑造其发育过程，并影响基因关联的稳定性。这一观察结果意味着环境响应可能会影响野生性状的进化。在此，我们研究了在苏格兰西北部圣基尔达岛希尔塔岛上的一群未受管理的索艾羊（Ovis aries）中，一系列两性异形性状的遗传结构如何随环境条件而变化。我们研究了在不同质量环境下，雄性索艾羊在出生后第一年中，角长、体重和寄生虫负荷之间的表型、遗传和环境（残差）协方差的稳定性。然后，我们研究了成年雌雄个体内部和之间不同环境下的相同协方差结构。我们发现，雄性羔羊的体重和寄生虫负荷存在显著的基因型与环境的相互作用，导致不同环境间的遗传相关性发生变化。角长在雄性中与体重存在遗传相关性，但在雌性中不存在，并且两性内部和之间性状的遗传相关性取决于成年期所经历的环境条件。在更有利的环境条件下，遗传相关性较小，这表明在良好环境中，具有性别特异性效应的基因座会得以表达。两性之间遗传相关性的降低可能会使两性各自沿着独立的进化轨迹发展。这项研究表明，在随时间变化的环境下，性状的遗传结构并不稳定，并突出了进化过程可能在很大程度上取决于生态条件这一事实。
