Numerous species of marine megafauna are at risk of extinction and understanding their genetic population structure and demographic history is essential for their conservation. We used mitochondrial DNA and 18 nuclear microsatellite loci, on the largest genetic dataset compiled to date on Australian humpback dolphins (eight sampling sites, 159 samples), to assess their genetic diversity, gene flow and past demographic history along the east coast of Queensland, Australia. Levels of genetic diversity were low (mtDNA: h = 0–0.52, π = 0–0.007; nDNA: Ho = 0.27–0.41; AR = 1.7–2.4). Both mitochondrial (Φ = 0.49, = 0.001) and nuclear markers (F = 0.14, = 0.001) showed strong genetic structure among sampling sites. Four putative populations were identified, with little contemporary gene flow (m = 0.017 to 0.047) among populations. Genetic divergence follows an isolation-by-distance model ( = 0.38, = 0.0001), with an apparent restriction in gene flow occurring at scales of 382–509 km. Estimates of contemporary effective population size were low ( = 11.5–31.2), with signatures of genetic bottlenecks for all putative populations about 50–150 generations ago. The current low levels of genetic diversity, gene flow, and effective population size in Australian humpback dolphins indicate the effects of historical population bottlenecks and/or founder events during the late Holocene period (~1250–3750 years ago); probably associated with sea level fall and increased intensity of El Niño Southern Oscillation-climatic events. Our results raise important conservation concerns and emphasize the vulnerability of Australian humpback dolphins to stochastic demographic, genetic and environmental processes. Conservation strategies should focus on promoting connectivity among local populations and reducing direct causes of human-related mortality.

中文翻译：

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受威胁的海豚物种——澳大利亚座头海豚的遗传多样性低、基因流有限和广泛的遗传瓶颈效应

许多海洋巨型动物物种面临灭绝的危险，了解它们的遗传种群结构和人口历史对于它们的保护至关重要。我们使用线粒体 DNA 和 18 个核微卫星位点，对澳大利亚座头海豚迄今为止编制的最大遗传数据集（8 个采样点，159 个样本）进行评估，以评估它们的遗传多样性、基因流和昆士兰东海岸过去的人口历史，澳大利亚。遗传多样性水平较低（mtDNA：h = 0–0.52，π = 0–0.007；nDNA：Ho = 0.27–0.41；AR = 1.7–2.4）。线粒体（Φ = 0.49，= 0.001）和核标记（F = 0.14，= 0.001）在采样点之间显示出很强的遗传结构。确定了四个假定的种群，种群之间几乎没有当代基因流动（m = 0.017 至 0.047）。遗传分化遵循距离隔离模型（= 0.38，= 0.0001），在 382-509 km 的尺度上基因流明显受到限制。对当代有效种群规模的估计较低（= 11.5-31.2），所有假定种群在大约 50-150 代以前都存在遗传瓶颈的特征。目前澳大利亚座头海豚的遗传多样性、基因流和有效种群规模水平较低，这表明了全新世晚期（约 1250-3750 年前）历史种群瓶颈和/或创始人事件的影响；可能与海平面下降和厄尔尼诺南方涛动气候事件强度增加有关。我们的研究结果引起了重要的保护问题，并强调了澳大利亚座头海豚对随机人口、遗传和环境过程的脆弱性。保护战略应侧重于促进当地居民之间的联系并减少与人类相关的死亡的直接原因。