Data from: Intraspecific trait variation and colonization sequence alter community assembly and disease epidemics

When individuals from multiple populations colonize a new habitat patch, intraspecific trait variation can make the arrival order of colonists an important factor for subsequent population and community dynamics. In particular, intraspecific priority effects (IPEs) allow early arrivers to limit the growth or establishment of later arrivers, even when competitively inferior on a per-capita basis. Through their effects on genes and traits, IPEs can alter short-term growth and long-term evolutionary change in single species metapopulations. Given their importance for intraspecific interactions, IPEs in a dominant species have the potential to affect the composition of entire communities. We conducted an experiment to determine whether and how arrival order and IPEs in the zooplankter Daphnia pulex affected its interactions with both competitors (the cladoceran Simocephalus vetulus) and parasites (the virulent fungus Metschnikowia bicuspidata). We found strong evidence for IPEs in Daphnia, as early arrivers inhibited late arrivers even when competitively inferior. These IPEs in Daphnia altered both the establishment success of interspecific competitors and the size of disease epidemics: early colonization by fast-growing D. pulex led to large Daphnia populations and low competitor establishment, but large disease epidemics. Early colonization by slow-growing D. pulex, on the other hand, resulted in small Daphnia populations with high competitor establishment, but smaller disease epidemics. Overall, our results demonstrate the importance of intraspecific variation and arrival order for community dynamics, and highlight IPEs as a general mechanism driving variation in natural communities.

当多个种群的个体拓殖新的生境斑块时，种内性状变异（intraspecific trait variation）会使得定植者的到达顺序成为后续种群与群落动态的关键影响因素。具体而言，种内优先效应（intraspecific priority effects, IPEs）可使早期到达的个体抑制后续到达个体的生长或定植，即便这些早期到达者在个体水平上的竞争能力处于劣势。通过对基因与性状的调控作用，IPEs可改变单物种种群集合（metapopulations）的短期生长动态与长期进化变化。鉴于其对种内相互作用的重要性，优势物种种内的IPEs有可能影响整个群落的组成结构。我们开展了一项实验，以探究浮游动物蚤状溞（Daphnia pulex）的到达顺序与IPEs是否、以及如何影响其与竞争者（枝角类物种西莫溞（Simocephalus vetulus））和寄生虫（强毒性真菌两孢梅奇酵母（Metschnikowia bicuspidata））之间的相互作用。我们在蚤状溞中发现了IPEs存在的有力证据：即便早期到达的个体在竞争能力上处于劣势，仍能抑制后续到达个体的生长与定植。这些蚤状溞的IPEs同时改变了种间竞争者的定植成功率与疾病流行规模：快速生长的蚤状溞早期定植会形成庞大的蚤状溞种群、降低竞争者的定植成功率，但同时会引发大规模的疾病流行。而慢速生长的蚤状溞早期定植则会形成小型的蚤状溞种群、提升竞争者的定植成功率，但疾病流行规模相对较小。总体而言，本研究结果证实了种内性状变异与到达顺序对群落动态的重要性，并凸显IPEs作为驱动自然群落变异的通用机制的关键作用。