Data from: Asymmetric competition impacts evolutionary rescue in a changing environment

Interspecific competition can strongly influence the evolutionary response of a species to a changing environment, impacting the chance that the species survives or goes extinct. Previous work has shown that when two species compete for a temporally shifting resource distribution, the species lagging behind the resource peak is the first to go extinct due to competitive exclusion. However, this work assumed symmetrically distributed resources and competition. Asymmetries can generate differences between species in population sizes, genetic variation and trait means. We show that asymmetric resource availability or competition can facilitate coexistence and even occasionally cause the leading species to go extinct first. Surprisingly, we also find cases where traits evolve in the opposite direction to the changing environment because of a ‘vacuum of competitive release’ created when the lagging species declines in number. Thus, the species exhibiting the slowest rate of trait evolution is not always the most likely to go extinct in a changing environment. Our results demonstrate that the extent to which species appear to be tracking environmental change and the extent to which they are preadapted to that change may not necessarily determine which species will be the winners and which will be the losers in a rapidly changing world.

种间竞争（interspecific competition）可显著影响物种应对变化环境的进化响应，进而影响该物种的存续或灭绝概率。先前研究表明，当两个物种为随时间动态变化的资源分布而竞争时，滞后于资源峰值的物种会因竞争排除（competitive exclusion）率先灭绝。但此类研究均假设资源与竞争关系呈对称分布。资源与竞争的不对称性可导致不同物种在种群规模、遗传变异及性状均值（trait means）上产生差异。本研究表明，不对称的资源可获得性或竞争关系可促进物种共存，甚至偶尔会让处于资源领先的物种率先灭绝。令人意外的是，我们还发现部分场景中，当滞后物种种群数量下降时，会产生“竞争释放真空（vacuum of competitive release）”效应，导致物种性状朝着与环境变化相反的方向演化。因此，在变化的环境中，性状演化速率最慢的物种并非总是最易灭绝的类群。本研究结果证实，在快速变化的世界中，物种对环境变化的追踪程度及其对该变化的预适应水平，未必能决定哪些物种会成为赢家、哪些会沦为输家。