Division of Ecology and Evolution, Research School of Biology, The Australian National University, Acton, ACT 2601, Canberra, Australia.
Institute of Zoology, University of Graz, Universitätsplatz 2, Graz, 8010, Austria.
Evolution. 2018 Sep;72(9):1904-1917. doi: 10.1111/evo.13554. Epub 2018 Jul 26.
Natural selection operates via fitness components like mating success, fecundity, and longevity, which can be understood as intermediaries in the causal process linking traits to fitness. In particular, sexual selection occurs when traits influence mating or fertilization success, which, in turn, influences fitness. We show how to quantify both these steps in a single path analysis, leading to better estimates of the strength of sexual selection. Our model controls for confounding variables, such as body size or condition, when estimating the relationship between mating and reproductive success. Correspondingly, we define the Bateman gradient and the Jones index using partial rather than simple regressions, which better captures how they are commonly interpreted. The model can be applied both to purely phenotypic data and to quantitative genetic parameters estimated using information on relatedness. The phenotypic approach breaks down selection differentials into a sexually selected and a "remainder" component. The quantitative genetic approach decomposes the estimated evolutionary response to selection analogously. We apply our method to analyze sexual selection in male dusky pipefish, Syngnathus floridae, and in two simulated datasets. We highlight conceptual and statistical limitations of previous path-based approaches, which can lead to substantial misestimation of sexual selection.
自然选择通过适应度成分起作用，例如交配成功率、繁殖力和寿命，这些可以被理解为将特征与适应度联系起来的因果过程中的中介。特别是当特征影响交配或受精成功率时，就会发生性选择，而这反过来又会影响适应度。我们展示了如何在单个路径分析中量化这两个步骤，从而更好地估计性选择的强度。我们的模型在估计交配和生殖成功率之间的关系时，控制了混杂变量，如体型或状况。相应地，我们使用偏回归而不是简单回归来定义 Bateman 梯度和 Jones 指数，这更好地捕捉了它们的常见解释。该模型可同时应用于纯粹的表型数据和使用亲缘关系信息估计的数量遗传参数。表型方法将选择差异分解为性选择和“剩余”成分。定量遗传方法类似地分解估计的对选择的进化反应。我们应用我们的方法来分析暗鳍天竺鱼雄性和两个模拟数据集的性选择。我们强调了以前基于路径的方法的概念和统计限制，这些限制可能导致对性选择的严重估计错误。
