Data from: Evolutionary processes, dispersal limitation and climatic history shape current diversity patterns of European dragonflies

We investigated the effects of contemporary and historical factors on the spatial variation of European dragonfly diversity. Specifically, we tested to what extent patterns of endemism and phylogenetic diversity of European dragonfly assemblages are structured by (i) phylogenetic conservatism of thermal adaptations and (ii) differences in the ability of post-glacial recolonization by species adapted to running waters (lotic) and still waters (lentic). We investigated patterns of dragonfly diversity using digital distribution maps and a phylogeny of 122 European dragonfly species, which we constructed by combining taxonomic and molecular data. We calculated total taxonomic distinctiveness and mean pairwise distances across 4,192 50 km × 50 km equal-area grid cells as measures of phylogenetic diversity. We compared species richness with corrected weighted endemism and standardized effect sizes of mean pairwise distances or residuals of total taxonomic distinctiveness to identify areas with higher or lower phylogenetic diversity than expected by chance. Broken-line regression was used to detect breakpoints in diversity–latitude relationships. Dragonfly species richness peaked in central Europe, whereas endemism and phylogenetic diversity decreased from warm areas in the south-west to cold areas in the north-east and with an increasing proportion of lentic species. Except for species richness, all measures of diversity were consistently higher in formerly unglaciated areas south of the 0°C isotherm during the Last Glacial Maximum than in formerly glaciated areas. These results indicate that the distributions of dragonfly species in Europe were shaped by both phylogenetic conservatism of thermal adaptations and differences between lentic and lotic species in the ability of post-glacial recolonization/dispersal in concert with the climatic history of the continent. The complex diversity patterns of European dragonflies provide an example of how integrating climatic and evolutionary history with contemporary ecological data can improve our understanding of the processes driving the geographical variation of biological diversity.

本研究探讨了当代与历史因素对欧洲蜻蜓多样性空间分异的影响。具体而言，我们针对欧洲蜻蜓类群的特有性（endemism）与系统发育多样性（phylogenetic diversity）格局的驱动机制展开检验：一是热适应的系统发育保守性（phylogenetic conservatism）的作用，二是适应流水生境（lotic）与静水生境（lentic）的物种在冰期后再定殖能力上的差异所产生的影响。本研究依托数字化分布地图以及整合分类学与分子数据构建的122种欧洲蜻蜓的系统发育树，对蜻蜓多样性格局展开分析。我们以4192个50km×50km的等面积网格单元（equal-area grid cells）为研究单元，计算总分类学独特性（total taxonomic distinctiveness）与平均成对距离（mean pairwise distances）作为系统发育多样性的衡量指标。我们将物种丰富度（species richness）与校正加权特有性（corrected weighted endemism）、平均成对距离的标准效应量（standardized effect sizes）或总分类学独特性的残差（residuals）进行对比，以此识别系统发育多样性显著高于或低于随机预期的区域。本研究采用分段回归（broken-line regression）分析，以检测多样性-纬度关系中的拐点。蜻蜓物种丰富度在欧洲中部达到峰值，而特有性与系统发育多样性则从西南温暖区域向东北寒冷区域递减，且随静水生境物种占比升高而降低。除物种丰富度外，所有多样性指标在末次冰盛期（Last Glacial Maximum）时0℃等温线（0°C isotherm）以南的原未冰盖区域，均显著高于原冰盖覆盖区域。上述结果表明，欧洲蜻蜓物种的分布格局由热适应的系统发育保守性、静水生境与流水生境物种间冰期后再定殖/扩散能力的差异，以及欧洲大陆气候历史共同塑造。欧洲蜻蜓复杂的多样性格局，为整合气候与演化历史及当代生态数据以深化我们对驱动生物多样性地理分异过程的认知提供了典型范例。