Data from: Trait evolution in adaptive radiations: modelling 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 amongst chosen species. Competition is modelled as a tendency of sympatric species to evolve towards 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 (ABC) 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 OU 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.

将生态过程纳入性状进化模型，对于解析演化变迁的过往驱动因素具有重要意义。长期以来，物种间相互作用被认为是性状进化的核心驱动因素。然而，目前仍缺乏能够刻画物种间相互作用的比较数据模型。此类模型所面临的核心挑战之一在于其解析难度极高，难以通过解析方式进行表述。本研究提出了一类包含选定物种种间竞争作用的性状进化系统发育模型：该模型将种间竞争定义为同域分布物种朝着彼此性状分化方向演化的趋势，由此产生性状离散分布与较高的系统发育信号。该模型预测跨物种的性状方差会升高，且无论是在整个演化支层面还是单一支系内部，进化速率均会出现减缓；此外，该模型还预测原本存在相关性的性状之间，其相关程度会出现下降。我们采用近似贝叶斯计算（Approximate Bayesian Computation, ABC）方法对模型参数进行估计。相较于布朗运动性状进化模型、奥恩斯坦-乌伦贝克（OU）模型以及早期爆发（Early-Burst）模型，当系统发育树包含20个以上物种时，本模型具备检测种间竞争作用的合理统计效力。我们将该模型应用于达尔文雀的喙形态进化分析，结果发现有证据表明种间竞争对喙长的进化存在影响。