Data from: Staying close to home? Genetic differentiation of rough-toothed dolphins near oceanic islands in the central Pacific Ocean

Rough-toothed dolphins have a worldwide tropical and subtropical distribution, yet little is known about the population structure and social organization of this typically open-ocean species. Although it has been assumed that pelagic dolphins range widely due to the lack of apparent barriers and unpredictable prey distribution, recent evidence suggests rough-toothed dolphins exhibit fidelity to some oceanic islands. Using the most comprehensively extensive dataset for this species to date, we assess the isolation and interchange of rough-toothed dolphins at the regional and oceanic scale within the central Pacific Ocean. Using mtDNA and microsatellite genotyping (nDNA), we analyzed samples of insular communities from the main Hawaiian (Kaua'i n = 93, O'ahu n = 9, Hawai'i n = 57), French Polynesian (n = 70) and Samoan (n = 16) archipelagos, and pelagic samples off the Northwestern Hawaiian Islands (n = 18). An overall AMOVA indicated strong genetic differentiation among islands (mtDNA FST = 0.265; p < 0.001; nDNA FST = 0.038; p < 0.001), as well as among archipelagos (mtDNA FST = 0.299; p < 0.001; nDNA FST = 0.055; p < 0.001). Shared haplotypes (n = 4) between the archipelagos may be a product of a relatively recent divergence and/or periodic exchange from poorly understood pelagic populations. Analyses using STRUCTURE and GENELAND identified four separate management units among archipelagos and within the Hawaiian Islands. These results confirm the presence of multiple insular populations within the Pacific and island-specific genetic isolation among populations attached to islands in each archipelago. Insular populations seem most prevalent where oceanographic conditions indicate high local productivity or a discontinuity with surrounding oligotrophic areas. Our findings have important implications for a little studied species that faces increasing anthropogenic threats around oceanic islands.

糙齿海豚（Rough-toothed dolphin）在全球热带及亚热带海域均有分布，但对于这种典型远洋物种的种群结构与社会组织，目前学界认知仍较为匮乏。尽管此前学界因缺乏明显地理屏障且猎物分布难以预测，而认为远洋海豚活动范围极广，但近期研究证据表明，糙齿海豚会对部分大洋岛屿表现出栖息地保真行为。本研究依托目前针对该物种最为全面的数据集，对中太平洋区域及大洋尺度下糙齿海豚的种群隔离与基因交流情况展开评估。本研究采用线粒体DNA（mtDNA）与微卫星基因分型（核DNA，nDNA）技术，对多个岛屿群落的样本进行分析：包括夏威夷主群岛（考艾岛Kaua'i：n=93、瓦胡岛O'ahu：n=9、夏威夷岛Hawai'i：n=57）、法属波利尼西亚群岛（n=70）、萨摩亚群岛（n=16）的岛屿群落样本，以及西北夏威夷群岛周边的远洋种群样本（n=18）。整体分子方差分析（AMOVA）结果显示，不同岛屿间（线粒体DNA FST=0.265；p<0.001；核DNA FST=0.038；p<0.001）以及不同群岛间（线粒体DNA FST=0.299；p<0.001；核DNA FST=0.055；p<0.001）均存在显著的遗传分化。各群岛间共有的4个单倍型，可能源于相对近期的种群分化，或是来自目前认知匮乏的远洋种群的周期性基因交流。采用STRUCTURE与GENELAND软件开展的群体结构分析，在各群岛内部以及夏威夷主群岛范围内，共鉴定出4个独立的保护管理单元。上述结果证实，太平洋区域存在多个岛屿特有种群，且各群岛内依附岛屿的种群间均存在岛屿特异性的遗传隔离。岛屿种群在当地海洋水文条件显示较高初级生产力，或是与周边寡营养海域存在生境断裂的区域最为常见。本研究的发现对于这类研究程度较低、且在大洋岛屿周边正面临日益加剧的人为活动威胁的物种而言，具有重要的保护管理启示意义。