Data from: Global analysis reveals that cryptic diversity is linked with habitat but not mode of life

The ubiquity of genetically distinct, cryptic species is limiting any attempt to estimate local or global biodiversity as well as impeding efforts to conserve species or control pests and diseases. Environmental factors or biological traits promoting rapid diversification into morphologically similar species remain unclear. Here, using a meta-analysis of 1230 studies using DNA sequences to search for cryptic diversity in metazoan taxa, we test two hypotheses regarding the frequency of cryptic taxa based on mode of life and habitat. First, after correcting for study effort and accounting for higher taxonomic affinities and biogeographical region of origins, our results do not support the hypothesis that cryptic taxa are more frequent among parasitic than free-living taxa. Second, in contrast the results support the hypothesis that cryptic taxa are more common in certain habitats than others: for a given study effort, more cryptic taxa are found in freshwater than in terrestrial or marine taxa. These findings suggest that the greater heterogeneity and fragmentation of freshwater habitats may promote higher rates of genetic differentiation among its inhabitants, a general pattern with serious implications for freshwater conservation biology.遗传分化显著的隐存物种（cryptic species）无处不在，这不仅阻碍了局域或全球生物多样性的评估工作，也制约了物种保护、病虫害防控的实践推进。目前，尚不清楚究竟是何种环境因素或生物学性状，推动类群快速分化为形态相似的隐存物种。本研究通过对1230项利用DNA序列搜索后生动物类群（metazoan taxa）隐存多样性的研究进行元分析（meta-analysis），基于生活方式与栖息环境两大维度，检验了两项关于隐存类群发生频率的假说。其一，在校正研究投入量、控制高级分类亲缘关系与起源生物地理区域的影响后，本研究结果不支持“寄生类群中的隐存类群发生频率高于自由生活类群”这一假说。其二，与之相对，研究结果支持第二项假说：即隐存类群在特定生境中的发生频率高于其他生境——在同等研究投入量下，淡水生境类群中发现的隐存类群数量多于陆生或海洋生境类群。上述研究结果表明，淡水生境更强的异质性与破碎化程度，可能推动其栖息类群产生更高水平的遗传分化，这一普遍性规律对淡水保护生物学具有重要的实践启示。