Data from: Non-random dispersal mediates invader impacts on the invertebrate community

(1) Dispersers are often not a random draw from a population, dispersal propensity being conditional on individual phenotypic traits and local conditions. This non-randomness consequently results in phenotypic differences between dispersers and non-dispersers and, in the context of biological invasions, in an invasion front made of individuals with a biased phenotype. This bias of phenotypes at the front may subsequently modulate the strength of ecological effects of an invasive species on invaded communities. (2) We recently demonstrated that more asocial mosquitofish (Gambusia affinis), one of the 100 worst invasive species, disperse further, suggesting a sociability-biased invasion front. As behavioural types are related to the strength of interspecific interactions, an invasion by a biased subset of individuals should have important ecological implications for native communities. (3) Here, we tested the impact of phenotypic biases in dispersing individuals (relative to non-dispersers) on prey communities in experimental mesocosms. (4) We show that dispersers reduce prey abundance more than do non-dispersers during the first 4 weeks after introduction, and that the disperser's social types are likely drivers of these differences. These differences in prey communities disappeared after 8 weeks suggesting prey community resilience against predation in these mesocosm ecosystems. (5) Consequently, we call for the integration of non-random dispersal, dispersal syndromes and more generally intraspecific variation into studies predicting the impacts of invasions.(1) 扩散个体通常并非种群内随机抽取的个体，其扩散倾向（dispersal propensity）取决于个体表型性状与局域环境条件。这种非随机性最终会导致扩散个体与非扩散个体间产生表型差异；在生物入侵（biological invasions）的语境下，入侵前沿（invasion front）将由存在表型偏倚的个体构成。入侵前沿的表型偏倚，后续会调节入侵物种对被入侵群落的生态效应强度。 (2) 我们近期的研究证实，在全球百大入侵物种之一的食蚊鱼（Gambusia affinis）中，社交性较弱的个体扩散距离更远，这表明入侵前沿存在社交性偏倚。由于行为类型与种间相互作用的强度密切相关，由偏倚个体子集所构成的入侵，势必会对本地群落产生重要的生态影响。 (3) 本研究针对“扩散个体相较于非扩散个体所携带的表型偏倚”对猎物群落的影响，在中型实验生态系统（mesocosms）中开展了实验检验。 (4) 研究结果显示，在投放后的前4周内，扩散个体对猎物丰度的抑制作用显著强于非扩散个体；且扩散个体的社交类型极可能是造成这一差异的核心驱动因素。该猎物群落差异在8周后完全消失，表明这些中型实验生态系统中的猎物群落具备抵御捕食的恢复力。 (5) 据此，我们呼吁将非随机扩散、扩散综合征（dispersal syndromes）以及更广泛的种内变异，纳入入侵影响预测相关研究框架之中。