Limits to behavioral evolution: the quantitative genetics of a complex trait under directional selection

Replicated selection experiments provide a powerful way to study how “multiple adaptive solutions” may lead to differences in the quantitative-genetic architecture of selected traits and whether this may translate into differences in the timing at which evolutionary limits are reached. We analyze data from 31 generations (n = 17,988) of selection on voluntary wheel running in house mice. The rate of initial response, timing of selection limit, and height of the plateau varied significantly between sexes and among the four selected lines. Analyses of litter size and realized selection differentials seem to rule out counterposing natural selection as a cause of the selection limits. Animal-model analyses showed that although the additive genetic variance was significantly lower in selected than control lines, both before and after the limits, the decrease was not sufficient to explain the limits. Moreover, directional selection promoted a negative covariance between additive and maternal ...重复选择实验是探究“多重适应性演化策略”如何导致受选性状的数量遗传学架构（quantitative-genetic architecture）产生差异，以及该差异是否会转化为演化极限到达时间差异的强有力研究手段。本研究分析了家鼠自愿转轮奔跑行为经31代选择的相关数据，样本量n=17988。初始选择响应速率、演化极限到达时间以及选择平台高度在不同性别间与四个选择品系间均存在显著差异。对产仔数与实际选择差（realized selection differentials）的分析似乎排除了反向自然选择作为演化极限成因的可能性。动物模型（Animal-model）分析结果显示，尽管在演化极限出现前后，选择品系的加性遗传方差（additive genetic variance）均显著低于对照品系，但该方差的降幅不足以解释演化极限的产生。此外，定向选择促使加性遗传方差与母体[...]之间产生负协方差。