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) 扩散者（dispersers）通常并非种群内的随机抽样个体，扩散倾向（dispersal propensity）取决于个体的表型性状（phenotypic traits）与局域环境条件。这种非随机性最终会导致扩散者与非扩散者之间出现表型差异；而在生物入侵（biological invasions）的语境下，这会形成由表型偏倚个体构成的入侵前沿（invasion front）。前沿处的表型偏倚后续可能会调控入侵物种对被入侵群落产生的生态效应强度。 (2) 我们近期的研究证实，位列全球百大恶性入侵物种的食蚊鱼（Gambusia affinis）中，社交性更低的个体扩散距离更远，这暗示存在受社交行为偏倚的入侵前沿。由于行为类型与种间相互作用强度相关，由偏倚个体子集构成的入侵事件，势必会对本地群落产生重要的生态影响。 (3) 本研究通过中型实验生态系统（mesocosms）实验，检验了扩散个体相对于非扩散个体的表型偏倚对猎物群落造成的影响。 (4) 实验结果显示，在引入后的前4周内，扩散者对猎物丰度的削减效果强于非扩散者；且扩散者的社交行为类型极有可能是造成这些差异的驱动因素。8周后，猎物群落的上述差异消失，这表明该中型实验生态系统中的猎物群落具备抵御捕食作用的恢复力。 (5) 据此，我们呼吁在预测入侵物种影响的相关研究中，纳入非随机扩散、扩散综合征（dispersal syndromes）以及更广泛意义上的种内变异（intraspecific variation）等要素。