Data from: Bucking the trend: Genetic analysis reveals high diversity, large population size and low differentiation in a deep ocean cetacean

Understanding the genetic structure of a population is essential to its conservation and management. We report the level of genetic diversity and determine the population structure of a cryptic deep ocean cetacean, the Gray's beaked whale (Mesoplodon grayi). We analysed 530bp of mitochondrial control region and 12 microsatellite loci from 94 individuals stranded around New Zealand and Australia. The samples cover a large area of the species distribution (~6,000 km) and were collected over a 22-year period. We show high genetic diversity (h=0.933-0.987, π=0.763-0.996% and Rs=4.22-4.37, He=0.624-0.675) and, in contrast to other cetaceans, we found a complete lack of genetic structure in both maternally and biparentally inherited markers. The oceanic habitats around New Zealand are diverse with extremely deep waters, seamounts and submarine canyons that are suitable for Gray's beaked whales and their prey. We propose that the abundance of this rich habitat has promoted genetic homogeneity in this species. Furthermore, it has been suggested that the lack of beaked whale sightings is as a result of their low abundance, but this is in contrast to our estimates of female effective population size based on mitochondrial data. In conclusion, the high diversity and lack of genetic structure can be explained by a historically large population size, in combination with no known exploitation, few apparent behavioural barriers and abundant habitat.解析种群的遗传结构，对于物种的保护与管理至关重要。本研究针对一种隐秘的深海鲸类——格雷氏喙鲸（Mesoplodon grayi），测定其遗传多样性水平并解析种群遗传结构。我们对采集自新西兰与澳大利亚周边海域的94头搁浅个体的线粒体控制区530bp序列，以及12个微卫星位点进行了分析。样本覆盖了该物种约6000公里的分布范围，且采集工作跨越了22年的时间跨度。研究结果显示该物种具有较高的遗传多样性（单倍型多样性h=0.933~0.987，核苷酸多样性π=0.763%~0.996%，等位基因丰富度Rs=4.22~4.37，期望杂合度He=0.624~0.675）；与其他鲸类不同的是，我们在母系遗传与双亲遗传的分子标记中均未发现任何遗传结构。新西兰周边海域的海洋生境类型多样，拥有极深的水域、海山与海底峡谷，这些环境均适宜格雷氏喙鲸及其猎物生存。我们推测，这类丰富多样的生境资源促成了该物种的遗传均质性。此外，此前有观点认为喙鲸目击记录稀少是因其种群数量较低，但这与我们基于线粒体数据估算的雌性有效种群规模结果相悖。综上，格雷氏喙鲸的高遗传多样性与无遗传结构特征，可由其历史上庞大的种群规模、未受已知人类捕捞活动影响、几乎不存在明显的行为阻隔，以及丰富的栖息生境共同解释。