Data from: Contrasting patterns of genetic diversity at three different genetic markers in a marine mammal metapopulation

Many studies use genetic markers to explore population structure and variability within species. However, only a minority use more than one type of marker and, despite increasing evidence of a strong link between heterozygosity and individual fitness, few ask whether diversity correlates with population trajectory. To address these issues, we analysed data from the Steller's sea lion, Eumetiopias jubatus, where three stocks are distributed over a vast geographic range and where both genetic samples and detailed demographic data have been collected from many diverse breeding colonies. To previously published mtDNA and microsatellite datasets we have added new data for Amplified Fragment Length Polymorphism (AFLP) markers, comprising 238 loci scored in 285 sea lions sampled from 23 natal rookeries. Genotypic diversity was low relative to most vertebrates, with only 37 loci (15.5%) being polymorphic. Moreover, contrasting geographic patterns of genetic diversity were found at the three markers, with Nei's gene diversity tending to be higher for AFLPs and microsatellites in rookeries of the western and Asian stocks, while the highest mtDNA values were found in the eastern stock. Overall, and despite strongly contrasting demographic histories, after applying phylogenetic correction we found little correlation between genetic diversity and either colony size or demography. In contrast, we were able to show a highly significant positive relationship between AFLP diversity and current population size across diverse pinniped species, even though equivalent analyses did not reveal significant trends for either microsatellites or mtDNA

诸多研究借助遗传标记（genetic markers）探究物种内的种群结构与种内变异。然而，仅有少数研究采用了不止一类遗传标记；尽管越来越多证据表明杂合性（heterozygosity）与个体适合度（individual fitness）之间存在强关联，但鲜有研究探讨遗传多样性是否与种群动态（population trajectory）相关。为解决上述问题，本研究对北海狮（Steller's sea lion）*Eumetiopias jubatus*的相关数据展开分析：该物种的3个种群单元（stocks）分布于广阔的地理范围，且研究团队已从多个不同的繁殖群中采集了遗传样本与详细的种群统计数据（demographic data）。针对此前已发表的线粒体DNA（mtDNA）与微卫星（microsatellite）数据集，本研究新增了扩增片段长度多态性（Amplified Fragment Length Polymorphism, AFLP）标记的相关数据：共238个基因座（loci）的分型结果，样本来自23个繁殖巢群（natal rookeries）的285头北海狮。相较于多数脊椎动物（vertebrates），该物种的基因型多样性偏低，仅37个基因座（15.5%）呈多态性。此外，三类标记的遗传多样性地理分布模式存在显著差异：西部与亚洲种群单元的繁殖巢群中，扩增片段长度多态性与微卫星的奈氏基因多样性（Nei's gene diversity）普遍更高，而线粒体DNA的最高值则出现在东部种群单元的巢群中。总体而言，尽管种群统计历史差异显著，经系统发育校正（phylogenetic correction）后，本研究未发现遗传多样性与繁殖群规模或种群统计特征之间存在明显关联。与之相反，本研究证实，在不同鳍足类（pinniped）物种中，扩增片段长度多态性多样性与当前种群规模之间存在极显著的正相关关系；不过针对微卫星或线粒体DNA的同类分析并未发现显著趋势。