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

The identification of species and population boundaries are important in both evolutionary biology and conservation. 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 affiliations and genetic connectivity of bottlenose dolphin (Tursiops spp.) populations off remote north-western 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 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 reproductive 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和保护生物学领域均具有重要意义。近年来，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相继涌现。本研究采用贝叶斯框架（Bayesian framework）与定量模型检验方法，评估了澳大利亚偏远西北海域外海宽吻海豚（Tursiops spp.）种群的物种归属与遗传连通性，重点关注拖网渔业中偶发误捕的远洋“外海”宽吻海豚。我们分析了71份海豚样本，采集自3个位于50米等深线（该拖网渔业的近岸边界）以外、离岸最远达170公里的海域，其中包括误捕个体以及与拖网渔船伴游的自由活动个体，同时还分析了12个沿岸站点（距海岸10公里以内）采集的273份海豚样本。基于19个核微卫星标记（nuclear microsatellite marker）的分析结果显示，渔业作业海域内的外海海豚与沿岸站点的海豚之间存在显著的种群遗传结构分化，同时沿岸站点的海豚种群内部也存在遗传分化，最终鉴定出3个独立的沿岸种群。此外，本研究未发现当前或历史时期存在基因流流入该渔业区域的外海种群，表明沿岸种群未向外海种群提供任何形式的种群补充。线粒体DNA（mitochondrial DNA）分析进一步佐证了外海种群与沿岸种群之间存在生殖隔离的研究结论：绝大多数外海个体与普通宽吻海豚（T. truncatus）构成单系群，而全部273份沿岸采样个体则与印度-太平洋宽吻海豚（T. aduncus）形成了支持度极高的单系群。本研究通过引入定量建模方法，将进化过程明确纳入研究考量，为保护物种的保护与管理决策提供了科学依据，该研究范式可为其他难以开展实地研究的同类种群提供参考范本。