Data from: Species ecological similarity modulates the importance of colonization history for adaptive radiation

Adaptive radiation is an important evolutionary process, through which a single ancestral lineage rapidly gives rise to multiple newly formed lineages that specialize in different niches. In the first-arrival hypothesis, David Lack emphasized the importance of species colonization history for adaptive radiation, suggesting that the earlier arrival of a diversifying species would allow it to radiate to a greater extent. Here, we report on the first rigorous experimental test of this hypothesis, using the rapidly evolving bacterium Pseudomonas fluorescens SBW25 and six different bacterial competitors. We show that the earlier arrival of P. fluorescens facilitated its diversification. Nevertheless, significant effects of colonization history, which led to alternative diversification trajectories, were observed only when the competitors shared similar niche and competitive fitness with P. fluorescens. These results highlight the important role of species colonization history, modified by their ecological differences, for adaptive radiation.

适应辐射（Adaptive radiation）是一类重要的演化过程：单一祖先类群可快速衍生出多个特化于不同生态位的新生类群。在先抵达假说（First-arrival hypothesis）中，大卫·拉克（David Lack）强调了物种定殖历史对适应辐射的重要性，提出分化类群越早抵达，其适应辐射的程度便越高。本研究以快速演化的细菌荧光假单胞菌SBW25（Pseudomonas fluorescens SBW25）与6株不同的细菌竞争者为实验材料，首次对该假说开展了严谨的实验验证。研究结果表明，荧光假单胞菌的提前定殖可促进其类群分化。不过，仅当竞争者与荧光假单胞菌具有相似的生态位与竞争适合度时，定殖历史才会产生显著影响，并导致类群出现差异化的分化路径。本研究结果凸显了经生态差异修饰后的物种定殖历史，在适应辐射过程中的关键作用。