Data from: Unexpected cryptic species diversity in the widespread coral Seriatopora hystrix masks spatial-genetic patterns of connectivity

Mounting evidence of cryptic species in a wide range of taxa highlights the need for careful analyses of population genetic datasets to unravel within-species diversity from potential interspecies relationships. Here we use microsatellite loci and hierarchical clustering analysis to investigate cryptic diversity in sympatric and allopatric (separated by 450 km) populations of the widespread coral Seriatopora hystrix on the Great Barrier Reef. Structure analyses delimited unique genetic clusters that were confirmed by phylogenetic and extensive population-level analyses. Each of four sympatric yet distinct genetic clusters detected within S. hystrix demonstrated greater genetic cohesion across regional scales than between genetic clusters within regions (<10km). Moreover, the magnitude of genetic differentiation between different clusters (>0.620 G”ST) was similar to the difference between S. hystrix clusters and the congener S. caliendrum (mean G”ST 0.720). Multiple lines of evidence, including differences in habitat specificity, mitochondrial identity, Symbiodinium associations and morphology, corroborate the nuclear genetic evidence that these distinct clusters constitute different species. Hierarchical clustering analysis combined with more traditional population genetic methods provide a powerful approach for delimiting species and should be regularly applied to ensure that ecological and evolutionary patterns interpreted for single species are not confounded by the presence of cryptic species.

越来越多的证据表明，各类分类类群（taxa）中存在隐存种（cryptic species），这凸显了对种群遗传学数据集（population genetic datasets）开展严谨解析的必要性——唯有通过此类分析，方能厘清物种内多样性与潜在种间关系的边界。本研究借助微卫星位点（microsatellite loci）与层级聚类分析（hierarchical clustering analysis），对大堡礁海域广布造礁珊瑚柱形珊瑚（Seriatopora hystrix）的同域分布（sympatric）种群，以及相隔450公里的异域分布（allopatric）种群中的隐存多样性展开探究。STRUCTURE群体结构分析划定了独特的遗传簇（genetic clusters），该结果经系统发育分析与大规模种群水平分析得以验证。在柱形珊瑚中发现的4个同域分布却彼此独立的遗传簇，其跨区域尺度的遗传凝聚力均高于区域内（<10公里）不同遗传簇间的遗传凝聚力。此外，不同遗传簇间的遗传分化程度（>0.620 G_ST）与柱形珊瑚遗传簇及其同属物种S. caliendrum间的遗传分化程度（平均G_ST为0.720）不相上下。多项佐证证据——涵盖生境特异性差异、线粒体基因型差异、虫黄藻（Symbiodinium）共生关系差异与形态学差异——均支持细胞核遗传证据：这些彼此独立的遗传簇实为不同物种。层级聚类分析结合更为经典的种群遗传学方法，为物种界定提供了高效可靠的研究路径，该方法应得到常规应用，以确保针对单一物种阐释的生态与进化模式不会因隐存种的存在而产生混淆。