Data from: Genetic isolation between coastal and fishery-impacted, offshore bottlenose dolphin (Tursiops spp.) populations

The identification of species and population boundaries is important in both evolutionary and conservation biology. In recent years, new population genetic and computational methods for estimating population parameters and testing hypotheses in a quantitative manner have emerged. Using a Bayesian framework and a quantitative model-testing approach, we evaluated the species status and genetic connectedness of bottlenose dolphin (Tursiops spp.) populations off remote northwestern Australia, with a focus on pelagic 'offshore' dolphins subject to incidental capture in a trawl fishery. We analysed 71 dolphin samples from three sites beyond the 50 m depth contour (the inshore boundary of the fishery) and up to 170 km offshore, including incidentally caught and free-ranging individuals associating with trawl vessels, and 273 dolphins sampled at 12 coastal sites inshore of the 50 m depth contour and within 10 km of the coast. Results from 19 nuclear microsatellite markers showed significant population structure between dolphins from within the fishery and coastal sites, but also among dolphins from coastal sites, identifying three coastal populations. Moreover, we found no current or historic gene flow into the offshore population in the region of the fishery, indicating a complete lack of recruitment from coastal sites. Mitochondrial DNA corroborated our findings of genetic isolation between dolphins from the offshore population and coastal sites. Most offshore individuals formed a monophyletic clade with common bottlenose dolphins (T. truncatus), while all 273 individuals sampled coastally formed a well-supported clade of Indo-Pacific bottlenose dolphins (T. aduncus). By including a quantitative modelling approach, our study explicitly took evolutionary processes into account for informing the conservation and management of protected species. As such, it may serve as a template for other, similarly inaccessible study populations.

物种与种群边界的鉴定，在进化生物学与保护生物学领域均具有核心意义。近年来，一系列可用于定量估算种群参数、检验科学假说的新型种群遗传学与计算方法应运而生。本研究依托贝叶斯框架（Bayesian framework）与定量模型检验方法，对澳大利亚偏远西北部海域外的宽吻海豚（Tursiops spp.）种群的物种地位与遗传连通性展开评估，重点关注拖网渔业中偶有捕获的远洋‘外洋（offshore）’型海豚。本研究共分析两类样本：其一为71份海豚组织样本，采集自3个位于50米等深线（该拖网渔业的近岸作业边界）以外、离岸最远达170公里的海域，样本涵盖渔业偶捕个体，以及伴随拖网渔船活动的自由游荡个体；其二为273份海豚样本，采集自12个近岸采样点，这些点位均处于50米等深线以内、距海岸10公里范围内。基于19个核微卫星（nuclear microsatellite）标记的遗传分析结果显示，渔业海域内的海豚种群与近岸采样点的海豚种群之间存在显著的遗传结构分化，同时近岸采样点的海豚种群内部亦存在分化，共鉴定出3个独立的近岸种群。此外，研究未发现当前或历史时期存在基因流向该渔业海域的外洋种群扩散的证据，表明近岸种群完全未向外洋种群进行个体补充。线粒体DNA（mitochondrial DNA）分析结果进一步佐证了外洋种群与近岸种群间的遗传隔离现象：绝大多数外洋个体与普通宽吻海豚（T. truncatus）构成单系群，而全部273份近岸采样个体则隶属于支持度极高的印太宽吻海豚（T. aduncus）分支。本研究通过引入定量建模思路，明确将进化过程纳入保护物种的管理与保育决策依据中，可为其他类似难以开展实地研究的种群提供研究范式参考。