Data from: Structure and phylogeography of two tropical predators, spinner (Stenella longirostris) and pantropical spotted (S attenuata) dolphins, from SNP data

Little is known about global patterns of genetic connectivity in pelagic dolphins, including how circumtropical pelagic dolphins spread globally following the rapid and recent radiation of the subfamily delphininae. In this study, we tested phylogeographic hypotheses for two circumtropical species, the spinner dolphin (Stenella longirostris) and the pantropical spotted dolphin (Stenella attenuata), using >3,000 nuclear DNA single nucleotide polymorphisms (SNPs) in each species. Analyses for population structure indicated significant genetic differentiation between almost all subspecies and populations in both species. Bayesian phylogeographic analyses of spinner dolphins showed deep divergence between Indo-Pacific, Atlantic, and eastern tropical Pacific Ocean (ETP) lineages. Despite high morphological variation, our results show very close relationships between endemic ETP spinner subspecies in relation to global diversity. The dwarf spinner dolphin is a monophyletic subspecies nested within a major clade of pantropical spinner dolphins from the Indian and western Pacific Ocean populations. Population-level division among the dwarf spinner dolphins was detected–with the northern Australia population being very different from that in Indonesia. In contrast to spinner dolphins, the major boundary for spotted dolphins is between offshore and coastal habitats in the ETP, supporting the current subspecies-level taxonomy. Comparing these species underscores the different scale at which population structure can arise, even in species that are similar in habitat (i.e., pelagic) and distribution.

目前学界对远洋海豚（pelagic dolphins）的全球遗传连接模式仍缺乏深入认知，包括环热带远洋海豚在海豚亚科（Delphininae）近期快速辐射演化后如何实现全球扩散。本研究针对两种环热带物种——飞旋海豚（*Stenella longirostris*）与热带斑海豚（*Stenella attenuata*），通过对每个物种超过3000个细胞核DNA单核苷酸多态性（single nucleotide polymorphisms, SNPs）位点的分析，检验其系统地理学假说。种群结构分析结果显示，两个物种的几乎所有亚种与种群间均存在显著的遗传分化。针对飞旋海豚的贝叶斯系统地理学分析表明，印度-太平洋、大西洋与东热带太平洋（eastern tropical Pacific Ocean, ETP）谱系间存在深度分化。尽管形态变异程度较高，但本研究结果显示，东热带太平洋特有飞旋海豚亚种与全球其他飞旋海豚类群的亲缘关系极为紧密。矮飞旋海豚为一单系亚种，嵌套于源自印度洋与西太平洋种群的热带飞旋海豚主要演化支中。研究同时检测到矮飞旋海豚内部的种群分化：澳大利亚北部种群与印尼种群差异显著。与飞旋海豚形成鲜明对比的是，热带斑海豚的主要种群分界位于东热带太平洋的远洋与近岸生境之间，这一结果支持当前的亚种级分类体系。对两个物种的比较研究凸显出，即使在生境（即远洋）与分布范围相似的物种中，种群结构的形成尺度也可能存在显著差异。