Data from: Variation in habitat connectivity generates positive correlations between species and genetic diversity in a metacommunity

An increasing number of studies are simultaneously investigating species diversity (SD) and genetic diversity (GD) in the same systems, looking for ‘species– genetic diversity correlations’ (SGDCs). From negative to positive SGDCs have been reported, but studies have generally not quantified the processes underlying these correlations. They were also mostly conducted at large biogeographical scales or in recently degraded habitats. Such correlations have not been looked for in natural networks of connected habitat fragments (metacommunities), and the underlying processes remain elusive in most systems. We investigated these issues by studying freshwater snails in a pond network in Guadeloupe (Lesser Antilles). We recorded SD and habitat characteristics in 232 ponds and assessed GD in 75 populations of two species. Strongly significant and positive SGDCs were detected in both species. Based on a decomposition of SGDC as a function of variance–covariance of habitat characteristics, we showed that connectivity (opportunity of water flow between a site and the nearest watershed during the rainy season) has the strongest contribution on SGDCs. More connective sites received both more alleles and more species through immigration resulting in both higher GD and higher SD. Other habitat characteristics did not contribute, or contributed negatively, to SGDCs. This is true of the desiccation frequency of ponds during the dry season, presumably because species markedly differ in their ability to tolerate desiccation. Our study shows that variation in environmental characteristics of habitat patches can promote SGDCs at metacommunity scale when the studied species respond homogeneously to these environmental characteristics.越来越多的研究同时在同一生态系统中探究物种多样性（species diversity, SD）与遗传多样性（genetic diversity, GD），以探寻“物种-遗传多样性相关性”（species–genetic diversity correlations, SGDCs）。已有研究报道了从负相关到正相关的各类SGDC，但现有研究大多未量化此类相关性背后的潜在过程，且多开展于大型生物地理尺度或近期受损的生境中。目前尚未针对连通生境片段组成的自然网络（即集合群落，metacommunities）开展此类相关性研究，且多数生态系统中该相关性的形成机制仍难以厘清。 我们以小安的列斯群岛瓜德罗普岛的池塘网络中的淡水螺类为研究对象，针对上述问题开展探究。我们在232个池塘中记录了物种多样性与生境特征，并对2个物种的75个种群开展了遗传多样性评估。两个物种中均检测到了显著正向的SGDC。基于生境特征的方差-协方差对SGDC的分解分析，我们发现连通性（雨季时研究位点与邻近流域间的水流交换机会）对SGDC的贡献最强。连通性更高的位点可通过物种与个体的迁入获得更多等位基因与物种，进而拥有更高的遗传多样性与物种多样性。其余生境特征要么对SGDC无显著贡献，要么产生负向影响——以旱季池塘的干涸频率为例，这可能是因为不同物种对干旱胁迫的耐受能力存在显著差异。 本研究表明，当研究物种对生境斑块的环境特征产生同质化响应时，生境斑块的环境变异可在集合群落尺度上促进SGDC的形成。