Data from: Sex ratio variation shapes the ecological effects of a globally introduced freshwater fish

Sex ratio and sexual dimorphism have long been of interest in population and evolutionary ecology, but consequences for communities and ecosystems remain untested. Sex ratio could influence ecological conditions whenever sexual dimorphism is associated with ecological dimorphism in species with strong ecological interactions. We tested for ecological implications of sex ratio variation in the sexually dimorphic western mosquitofish, Gambusia affinis. This species causes strong pelagic trophic cascades and exhibits substantial variation in adult sex ratios. We found that female-biased populations induced stronger pelagic trophic cascades compared with male-biased populations, causing larger changes to key community and ecosystem responses, including zooplankton abundance, phytoplankton abundance, productivity, pH and temperature. The magnitude of such effects indicates that sex ratio is important for mediating the ecological role of mosquitofish. Because both sex ratio variation and sexual dimorphism are common features of natural populations, our findings should encourage broader consideration of the ecological significance of sex ratio variation in nature, including the relative contributions of various sexually dimorphic traits to these effects.性比（sex ratio）与性二态性（sexual dimorphism）长期以来一直是种群生态学与进化生态学领域的核心研究议题，但其对群落与生态系统的影响迄今尚未得到实证检验。当存在强生态相互作用的物种，其性二态性与生态二态性（ecological dimorphism）相关联时，性比便可能对生态条件产生调控作用。本研究以具有性二态性的西部食蚊鱼（Gambusia affinis，western mosquitofish）为研究对象，探究其性比变异的生态效应。该物种可引发显著的远洋带营养级联效应，且其成体性比存在显著变异。研究结果显示，与雄性占优的种群相比，雌性占优的种群可诱发更强的远洋带营养级联效应，对群落与生态系统的关键响应指标造成更大幅度的改变，这些指标涵盖浮游动物丰度、浮游植物丰度、生态系统生产力、pH值与水温。此类效应的强度表明，性比在介导食蚊鱼的生态功能中具有重要意义。鉴于性比变异与性二态性均为自然种群的普遍特征，本研究结果应能推动学界更广泛地审视自然中性比变异的生态重要性，包括各类性二态性状对上述效应的相对贡献。