Data from: Trait evolution in adaptive radiations: modeling and measuring interspecific competition on phylogenies

The incorporation of ecological processes into models of trait evolution is important for understanding past drivers of evolutionary change. Species interactions have long been thought to be key drivers of trait evolution. However, models for comparative data that account for interactions between species are lacking. One of the challenges is that such models are intractable and difficult to express analytically. Here we present phylogenetic models of trait evolution that include interspecific competition among chosen species. Competition is modeled as a tendency of sympatric species to evolve toward difference from one another, producing trait overdispersion and high phylogenetic signal. The model predicts elevated trait variance across species and a slowdown in evolutionary rate both across the clade and within each branch. The model also predicts a reduction in correlation between otherwise correlated traits. We use an approximate Bayesian computation approach to estimate model parameters. We find reasonable power to detect competition in sufficiently large (20+ species) trees compared with Brownian trait evolution and with Ornstein-Uhlenbeck and early burst models. We apply the model to examine the evolution of bill morphology of Darwin’s finches and find evidence that competition affects the evolution of bill length.将生态过程整合至性状进化（trait evolution）模型中，对于解析进化改变的既往驱动因素具有重要意义。长期以来，物种间相互作用（species interactions）被视作性状进化的关键驱动因子。然而，目前仍缺乏能够考量物种间相互作用的比较数据模型。此类模型面临的一项核心挑战在于其计算复杂度极高，且难以通过解析方式进行表述。本文提出一类包含选定物种种间竞争（interspecific competition）的性状进化系统发育（phylogenetic）模型：我们将种间竞争建模为同域物种（sympatric species）朝着彼此性状差异方向演化的倾向，由此可产生性状过度离散（trait overdispersion）与较高的系统发育信号（phylogenetic signal）。该模型可做出如下预测：其一，在整个支系（clade）及各分支内部，物种间的性状方差均会升高，进化速率将出现放缓；其二，原本存在相关性的性状之间的相关性会有所降低。我们采用近似贝叶斯计算（approximate Bayesian computation）方法估算模型参数。相较于布朗运动性状进化（Brownian trait evolution）、奥恩斯坦-乌伦贝克（Ornstein-Uhlenbeck）模型以及早爆发（early burst）模型，在包含20种及以上物种的足够大的系统发育树中，本模型具备良好的竞争信号检测能力。我们将该模型应用于达尔文雀（Darwin’s finches）的喙形态（bill morphology）进化研究，获取到竞争影响喙长进化的相关证据。