Data from: A meta-analysis of nestedness and turnover components of beta diversity across organisms and ecosystems

The number of studies investigating the nestedness and turnover components of beta diversity has increased substantially, but our general understanding of the drivers of turnover and nestedness remains elusive. Here, we examined the effects of species traits, spatial extent, latitude and ecosystem type on the nestedness and turnover components of beta diversity. From the 99 studies that partition total beta diversity into its turnover and nestedness components, we assembled 269 and 259 data points for the pairwise and multiple site beta-diversity metrics, respectively. Our data covered a broad variation in species dispersal type, body size and trophic position. The data were from freshwater, marine and terrestrial realms, and encompassed geographical areas from the tropics to near polar regions. We used linear modelling as a meta-regression tool to analyse the data.Pairwise turnover, multiple site turnover and total beta diversity all decreased significantly with latitude. In contrast, multiple site nestedness showed a positive relationship with latitude. Beta-diversity components did not generally differ among the realms. The turnover component and total beta diversity increased with spatial extent, whereas nestedness was scale invariant for pairwise metrics. Multiple site beta-diversity components did not vary with spatial extent. Surprisingly, passively dispersed organisms had lower turnover and total beta diversity than flying organisms. Body size showed a relatively weak relationship with beta diversity but had important interactions with trophic position, thus also affecting beta diversity via interactive effects. Producers had significantly higher average pairwise turnover and total beta diversity than carnivores. The present results provide evidence that species turnover, being consistently the larger component of total beta diversity, and nestedness are related to the latitude of the study area and intrinsic organismal features. We showed that two beta-diversity components had generally opposing patterns with regard to latitude. We highlight that beta-diversity partition may give additional insights into the underlying causes of spatial variability in biotic communities compared with total beta diversity alone.

针对β多样性（Beta diversity）嵌套性（nestedness）与周转组分（turnover components）的研究数量已大幅增长，但学界对周转与嵌套性的驱动机制仍不甚明晰。本研究旨在探究物种性状、空间幅度、纬度以及生态系统类型对β多样性嵌套性与周转组分的影响。我们从99项将总β多样性划分为周转与嵌套组分的研究中，分别汇编得到成对样地β多样性测度与多站点β多样性测度的269组和259组数据点。本次数据集涵盖了物种扩散类型、体型大小以及营养位的广泛变异，数据覆盖淡水、海洋与陆地三大生境域，研究区域涵盖从热带至近极地的广泛地理范围。本研究采用线性模型作为元回归（meta-regression）分析工具对数据集开展分析。结果显示，成对样地周转、多站点周转以及总β多样性均随纬度升高而显著降低；与之相反，多站点嵌套性则与纬度呈显著正相关关系。不同生境域间的β多样性组分总体上并无显著差异。周转组分与总β多样性随空间幅度增大而升高，而成对样地测度下的嵌套性则表现出尺度不变性；多站点β多样性组分则不随空间幅度发生变化。令人意外的是，被动扩散生物的周转水平与总β多样性均低于飞行生物。体型大小与β多样性的相关性相对较弱，但与营养位存在显著的交互作用，进而通过交互效应间接影响β多样性。生产者的平均成对样地周转值与总β多样性均显著高于肉食动物。本研究结果表明，作为总β多样性中占比始终更高的组分，物种周转与嵌套性均与研究区域的纬度以及生物自身固有特征密切相关。我们证实，两类β多样性组分在纬度梯度上总体呈现相反的变化格局。相较于仅分析总β多样性，对β多样性进行组分拆分，可为揭示生物群落空间变异的深层成因提供更多洞见。