Data from: Life history determines biogeographical patterns of soil bacterial communities over multiple spatial scales

The extent to which the distribution of soil bacteria is controlled by local environment versus spatial factors (e.g., dispersal, colonisation limitation, evolutionary events) is poorly understood and widely debated. Our understanding of biogeographic controls in microbial communities is likely hampered by the enormous environmental variability encountered across spatial scales and the broad diversity of microbial life histories. Here we constrained environmental factors (soil chemistry, climate, above-ground plant community) to investigate the specific influence of space, by fitting all other variables first, on bacterial communities in soils over distances from m to 102 km. We found strong evidence for a spatial component to bacterial community structure that varies with scale and organism life history (dispersal and survival ability). Geographic distance had no influence over community structure for organisms known to have survival stages, but the converse was true for organisms thought to be less hardy. Community function (substrate utilisation) was also shown to be highly correlated to community structure, but not to abiotic factors, suggesting non-stochastic determinants of community structure are important Our results support the view that bacterial soil communities are constrained by both edaphic factors and geographic distance, and further show that the relative importance of such constraints depends critically on the taxonomic resolution used to evaluate spatio-temporal patterns of microbial diversity, as well as life-history of the groups being investigated, much as is the case for macro-organisms.

土壤细菌的分布格局在多大程度上受局域环境与空间因子（spatial factors，如扩散、定殖限制、进化事件）调控，目前尚未得到充分阐明，且存在广泛学术争议。当前我们对微生物群落（microbial communities）生物地理调控因子的认知，很可能受限于不同空间尺度下的巨大环境异质性，以及微生物生活史的广泛多样性。本研究首先通过拟合所有其他变量以限定环境因子（土壤化学性质、气候、地上植物群落），从而探究空间因素对跨度范围从米级至100公里的土壤细菌群落的特异性影响。我们发现，细菌群落结构存在显著的空间组分，且该组分随空间尺度与生物生活史（即扩散与存活能力）发生变化。对于已知具备存活阶段的微生物类群，地理距离对其群落结构并无影响；而对于被认为抗逆性较弱的类群，结果则恰好相反。群落功能（community function，即底物利用能力（substrate utilisation））同样被证实与群落结构高度相关，但与非生物因子（abiotic factors）无关，这表明群落结构的非随机决定因子具有重要调控作用。本研究结果支持这一学术观点：土壤细菌群落同时受土壤因子（edaphic factors）与地理距离的约束；且进一步表明，此类约束的相对重要性，关键取决于评估微生物多样性时空格局时所采用的分类学分辨率（taxonomic resolution），以及所研究类群的生活史特征，这一点与大型生物（macro-organisms）的相关研究情况高度一致。