Data from: A worldwide perspective on the population structure and genetic diversity of bottlenose dolphins (Tursiops truncatus) in New Zealand

Bottlenose dolphins (Tursiops truncatus) occupy a wide range of coastal and pelagic habitats throughout tropical and temperate waters worldwide. In some regions, "inshore" and "offshore" forms or ecotypes differ genetically and morphologically, despite no obvious boundaries to interchange. Around New Zealand, bottlenose dolphins inhabit 3 coastal regions: Northland, Marlborough Sounds, and Fiordland. Previous demographic studies showed no interchange of individuals among these populations. Here, we describe the genetic structure and diversity of these populations using skin samples collected with a remote biopsy dart. Analysis of the molecular variance from mitochondrial DNA (mtDNA) control region sequences (n = 193) showed considerable differentiation among populations (Fst = 0.17, Φst = 0.21, P < 0.001) suggesting little or no female gene flow or interchange. All 3 populations showed higher mtDNA diversity than expected given their small population sizes and isolation. To explain the source of this variation, 22 control region haplotypes from New Zealand were compared with 108 haplotypes worldwide representing 586 individuals from 19 populations and including both inshore and offshore ecotypes as described in the Western North Atlantic. All haplotypes found in the Pacific, regardless of population habitat use (i.e., coastal or pelagic), are more divergent from populations described as inshore ecotype in the Western North Atlantic than from populations described as offshore ecotype. Analysis of gene flow indicated long-distance dispersal among coastal and pelagic populations worldwide (except for those haplotypes described as inshore ecotype in the Western North Atlantic), suggesting that these populations are interconnected on an evolutionary timescale. This finding suggests that habitat specialization has occurred independently in different ocean basins, perhaps with Tursiops aduncus filling the ecological niche of the inshore ecotype in some coastal regions of the Indian and Western Pacific Oceans.

宽吻海豚（Tursiops truncatus）广泛分布于全球热带及温带海域的近岸与远洋生境中。部分区域内，尽管个体间不存在明显的交流屏障，“近岸型”与“远洋型”两类形态或生态型（ecotype）仍存在遗传与形态学差异。在新西兰周边海域，宽吻海豚栖息于3个近岸区域：北地（Northland）、马尔堡峡湾（Marlborough Sounds）与菲奥德兰（Fiordland）。此前的种群生态学研究表明，这3个种群间无个体交流现象。
本研究借助远程活检镖（remote biopsy dart）采集的皮肤样本，对这3个种群的遗传结构与遗传多样性展开描述。对193条线粒体DNA（mtDNA）控制区序列的分子变异分析结果显示，种群间存在显著遗传分化（Fst=0.17，Φst=0.21，P<0.001），表明雌性个体的基因交流极少甚至不存在。尽管种群规模较小且彼此隔离，3个种群的mtDNA多样性均高于预期水平。
为阐释该多样性的来源，研究人员将新西兰种群的22个控制区单倍型（haplotype），与全球19个种群的108个单倍型（涵盖586个个体）进行比对；后者包含西北大西洋海域已报道的近岸型与远洋型两类生态型。太平洋海域发现的所有单倍型，无论其种群的生境类型为近岸还是远洋，与西北大西洋的近岸型种群相比，与西北大西洋远洋型种群的遗传差异均更小。
基因流（gene flow）分析结果显示，全球近岸与远洋种群间存在长距离扩散现象（西北大西洋近岸型单倍型类群除外），表明这些种群在进化时间尺度上存在遗传联系。该研究结果表明，不同大洋盆地均独立演化出了生境特化类群；在印度洋与西太平洋的部分近岸区域，印太宽吻海豚（Tursiops aduncus）或已填补了近岸生态型的生态位（ecological niche）。