Data from: Selection analysis on the rapid evolution of a secondary sexual trait

Evolutionary analyses of population translocations (experimental or accidental) have been important in demonstrating speed of evolution because they subject organisms to abrupt environmental changes that create an episode of selection. Yet the strength of selection in such studies is rarely measured, therefore limiting our understanding of the evolutionary process. This contrasts with long-term, mark-recapture studies of unmanipulated populations that measure selection directly, yet rarely reveal evolutionary change. Here we present a study of experimental evolution of male colour in Trinidadian guppies where we tracked both evolutionary change and individual-based measures of selection. Guppies were translocated from a predator-rich to a low-predation environment within the same stream system. We used a combination of common garden experiments and monthly sampling of individuals to measure the phenotypic and genetic divergence of male coloration between ancestral and derived fish. Results show rapid evolutionary increases in orange coloration in both populations (1 year or 3 generations), replicating the results of previous studies. Unlike previous studies, we linked this evolution to an individual-based analysis of selection. By quantifying individual reproductive success and survival we show, for the first time, that males with more orange and black pigment have higher reproductive success, but males with more black pigment also have higher risk of mortality. The net effect of selection is thus an advantage of orange but not black coloration, as reflected in the evolutionary response. This highlights the importance of considering all components of fitness when understanding the evolution of sexually selected traits in the wild.针对种群易位（实验性或偶然性）的进化分析，在验证进化速率方面始终发挥着关键作用——此类研究将生物暴露于突发环境变化之中，进而引发一轮选择事件。然而此类研究中，选择强度鲜有被量化，这极大限制了我们对进化过程的认知。这与针对未受干预种群的长期标记重捕研究形成鲜明反差：后者可直接测定选择强度，却极少能观测到进化变化。本研究针对特立尼达孔雀鱼（Trinidadian guppies）的雄性体色开展实验进化研究，同时追踪了进化变化与基于个体的选择量化指标。研究种群源自同一溪流系统，从捕食者密集的生境易位至低捕食压力的生境。我们结合同质园实验与个体月度采样方案，对祖先种群与衍生种群雄性体色的表型与遗传分化进行了定量测定。研究结果显示，两个种群的雄性橙色体色均出现快速进化性提升（耗时1年或3个世代），这一结果重复了既往研究的发现。与既往研究不同的是，本研究将该进化事件与基于个体的选择分析建立了直接关联。通过量化个体繁殖成功率与存活率，我们首次证实：橙色与黑色色素含量更高的雄性拥有更高的繁殖成功率，但黑色色素更多的雄性死亡率也更高。因此，选择的净效应为橙色体色具备进化优势，而黑色体色并无此优势，这与进化响应的观测结果一致。该发现凸显了在探究野外性选择性状的进化机制时，综合考量适合度所有组成部分的重要性。