Data from: Sexual selection reinforces a higher flight endurance in urban damselflies

Urbanisation is among the most important and globally rapidly increasing anthropogenic processes, and is known to drive rapid evolution. Habitats in urbanised areas typically consist of small, fragmented and isolated patches, which is expected to select for a better locomotor performance, along with its underlying morphological traits. This, in turn, is expected to cause differentiation in selection regimes, as populations with different frequency distributions for a given trait will span different parts of the species’ fitness function. Yet, very few studies considered differentiation in phenotypic traits associated with patterns in habitat fragmentation and isolation along urbanisation gradients, and none considered differentiation in sexual selection regimes. We investigated differentiation in flight performance and flight-related traits, and sexual selection on these traits across replicated urban and rural populations of the scrambling damselfly Coenagrion puella. To disentangle direct and indirect paths going from phenotypic traits over performance to mating success, we applied a path analysis approach. We report for the first time direct evidence for the expected better locomotor performance in urban compared to rural populations. This matches a scenario of spatial sorting, whereby only the individuals with the best locomotor abilities colonise the isolated urban populations. The covariation patterns and causal relationships among the phenotypic traits, performance and mating success strongly depended on the urbanisation level. Notably, we detected sexual selection for a higher flight endurance only in urban populations, indicating that the higher flight performance of urban males was reinforced by sexual selection. Taken together, our results provide a unique proof of the interplay between sexual selection and adaptation to human-altered environments.

城市化（urbanisation）是全球范围内最重要且增速最快的人为活动过程之一，已知其可驱动快速进化。城市化区域的生境通常由小型、破碎化且孤立的斑块组成，这被认为会对更优异的运动表现（locomotor performance）及其背后的形态性状（morphological traits）产生选择压力。这进而会导致选择模式的分化：携带某一特定性状频率分布存在差异的种群，会跨越物种适合度函数（fitness function）的不同区间。然而，目前极少有研究关注沿城市化梯度分布的生境破碎化与隔离模式相关的表型性状（phenotypic traits）分化，更无研究涉及性选择模式的分化。我们以争抢型普通蓝豆娘（Coenagrion puella）的多个重复城市与乡村种群为研究对象，探究了飞行表现及飞行相关性状的分化，以及这些性状在种群间的性选择差异。为了厘清从表型性状经运动表现到交配成功率（mating success）的直接与间接路径，我们采用了路径分析（path analysis）方法。我们首次报道了相较于乡村种群，城市种群具备更优异运动表现的直接证据，这符合空间分选（spatial sorting）的情景：即仅运动能力最强的个体能够定居于孤立的城市种群中。表型性状、运动表现与交配成功率之间的协变模式与因果关系，强烈依赖于城市化水平。值得注意的是，我们仅在城市种群中检测到针对更高飞行耐力的性选择，这表明城市雄性更高的飞行表现得到了性选择的强化。综上，我们的研究结果为性选择与人类改造环境的适应之间的相互作用提供了独特的佐证。