Data from: Environmental variables explain genetic structure in a beetle-associated nematode

The distribution of a species is a complex expression of its ecological and evolutionary history and integrating population genetic, environmental, and ecological data can provide new insights into the effects of the environment on the population structure of species. Previous work demonstrated strong patterns of genetic differentiation in natural populations of the hermaphroditic nematode Pristionchus pacificus in its La Réunion Island habitat, but gave no clear understanding of the role of the environment in structuring this variation. Here, we present what is to our knowledge the first study to statistically evaluate the role of the environment in shaping the structure and distribution of nematode populations. We test the hypothesis that genetic structure in P. pacificus is influenced by environmental variables, by combining population genetic analyses of microsatellite data from 18 populations and 370 strains, with multivariate statistics on environmental data, and species distribution modelling. We assess and quantify the relative importance of environmental factors (geographic distance, altitude, temperature, precipitation, and beetle host) on genetic variation among populations. Despite the fact that geographic populations of P. pacificus comprise vast genetic diversity sourced from multiple ancestral lineages, we find strong evidence for local associations between environment and genetic variation. Further, we show that significantly more genetic variation in P. pacificus populations is explained by environmental variation than by geographic distances. This supports a strong role for environmental heterogeneity vs. genetic drift in the divergence of populations, which we suggest may be influenced by adaptive forces.

物种的分布格局是其生态与演化历史的综合体现，整合种群遗传学、环境科学与生态学数据，能够为解析环境对物种种群结构的影响提供全新视角。此前的研究已在留尼旺岛（La Réunion Island）生境中的雌雄同体线虫帕氏小杆线虫（Pristionchus pacificus）自然种群中，发现了显著的遗传分化模式，但尚未明确环境在塑造该遗传变异中的作用。本研究据我们所知首次采用统计学方法，评估环境在线虫种群结构与分布塑造过程中的作用。本研究结合针对18个种群、370个菌株的微卫星（microsatellite）数据开展的种群遗传学分析、环境数据多元统计分析与物种分布建模，对"帕氏小杆线虫（Pristionchus pacificus）的遗传结构受环境变量影响"这一假说进行了验证。我们对地理距离、海拔、温度、降水以及甲虫宿主等环境因素在种群间遗传变异中的相对重要性进行了评估与量化。尽管帕氏小杆线虫（Pristionchus pacificus）的地理种群拥有源自多个祖先支系的丰富遗传多样性，但本研究发现了环境与遗传变异之间存在本地关联的有力证据。此外，研究表明，相较于地理距离，环境变异能够解释帕氏小杆线虫（Pristionchus pacificus）种群中更多的遗传变异。该结果支持环境异质性而非遗传漂变在种群分化中发挥主导作用，我们推测这一过程可能受到适应性演化力量的影响。