Characterizing selection in black-throated blue warblers using a sexual network approach

Our understanding of trait evolution is built upon studies that examine the correlation between traits and fitness, most of which implicitly assume all individuals experience similar selective environments. However, accounting for differences in selective pressures, such as variation in the social environment, can advance our understanding of how selection shapes individual traits and subsequent fitness. In this study, we test whether variation in the social environment affects selection on individual phenotype. We apply a new sexual network framework to quantify each male's social environment as the mean body size of his primary competitors. We test for direct and social selection on male body size using a 10-year dataset on black-throated blue warblers (Setophaga caerulescens), a territorial species for which body size is hypothesized to mediate competition for mates. We found that direct selection on body size was weak and non-significant, as was social selection via the body size of...我们对性状演化的认知，建立于探究性状与适合度相关性的研究之上；这类研究大多隐含假定所有个体所处的选择环境均一致。然而，若将选择压力的差异——比如社会环境的变异——纳入考量，则可深化我们对选择如何塑造个体性状及后续适合度的认知。本研究旨在检验社会环境的变异是否会作用于个体表型所受的选择压力。我们采用一种全新的性选择网络框架，将每只雄性的社会环境量化为其主要竞争者的平均体型大小。我们基于一项针对黑喉蓝林莺（Setophaga caerulescens）的十年期数据集，检验雄性体型所受的直接选择与社会选择；该物种为领域性鸟类，此前研究推测体型可介导其配偶竞争过程。研究结果显示，针对体型的直接选择强度较弱且不显著，通过竞争者体型介导的社会选择亦同理……