Data from: Convergence and non-convergence in ecological, phenotypic, and genetic divergence across replicate population pairs of lake and stream stickleback

Convergent (or parallel) evolution provides strong evidence for a deterministic role of natural selection: similar phenotypes evolve when independent populations colonize similar environments. In reality, however, independent populations in similar environments always show some differences: some non-convergent evolution is present. It is therefore important to explicitly quantify the convergent and non-convergent aspects of trait variation, and to investigate the ecological and genetic explanations for each. We performed such an analysis for threespine stickleback (Gasterosteus aculeatus) populations inhabiting lake and stream habitats in independent watersheds. Morphological traits differed in the degree to which lake-stream divergence was convergent across watersheds. Some aspects of this variation were correlated with ecological variables related to diet, presumably reflecting the strength and specifics of divergent selection. Furthermore, a genetic scan revealed some markers that diverged between lakes and streams in many of the watersheds and some that diverged in only a few watersheds. Moreover, some of the lake-stream divergence in genetic markers was associated within some of the lake-stream divergence in morphological traits. Our results suggest that convergent evolution, and deviations from it, are primarily the result of natural selection, which corresponds in only some respect to the dichotomous habitat classifications frequently used in such studies.

趋同进化（Convergent evolution，又称平行进化）为自然选择的决定性作用提供了强有力的证据：当独立种群拓殖至相似环境时，会演化出相似的表型（phenotype）。然而在现实中，处于相似环境中的独立种群总会存在一定差异，即存在非趋同进化现象。因此，明确量化性状变异中的趋同与非趋同成分，并分别探究其生态学与遗传学解释，就显得尤为重要。本研究针对栖息于独立流域湖泊与溪流生境的三刺棘鱼（threespine stickleback，学名*Gasterosteus aculeatus*）种群开展了此类分析。形态性状在不同流域间的湖-溪分化趋同程度存在差异。这类变异的部分成分与饮食相关的生态学变量存在关联，这大致反映了歧化选择的强度与具体作用模式。此外，遗传扫描（genetic scan）发现，部分遗传标记（genetic marker）在多数流域的湖泊与溪流种群间发生了分化，而另一些仅在少数流域中出现分化。进一步而言，部分遗传标记的湖-溪分化与部分形态性状的湖-溪分化存在关联。本研究结果表明，趋同进化及其偏离现象主要由自然选择驱动，而这仅在一定程度上契合此类研究中常用的二分法生境分类方式。