Genetic variation in sea otters (Enhydra lutris) from the North Pacific with relevance to the threatened Southwest Alaska distinct population segment

For the sea otter (Enhydra lutris), genetic population structure is an
area of research that has not received significant attention, especially
in Southwest Alaska where that distinct population segment has been listed
as threatened since 2005 pursuant to the U.S. Endangered Species Act. In
this study, 501 samples from 14 locations from Prince William Sound,
Alaska to the Commander Islands in Russia were analyzed for variation at
13 microsatellite loci. Our results indicate a high degree of genetic
divergence among the 14 locations (FST = 0.12) with gene flow conforming
to the isolation by distance (IBD) model (r2 = 0.491, p < 0.05).
The 14 sampling locations formed six geographic associations in clustering
and ordination analyses that likely correspond to remnant population
lineages: 1) Southcentral Alaska, 2) Kodiak and North Alaska Peninsula, 3)
South Alaska Peninsula and Bristol Bay, 4) Eastern Aleutian, 5) Western
Aleutian, and 6) the Commander Islands. Except for South Alaska Peninsula
and Bristol Bay, these clusters closely agree with previously defined
stock and management unit boundaries. Our results reveal significant
genetic population structure and are generally congruent with current
management strategies for the threatened Southwest Alaska distinct
population segment.

对于海獭（Enhydra lutris）而言，遗传种群结构研究领域尚未得到充分关注，尤其是在阿拉斯加西南部——该区域的独特种群片段自2005年起依据美国《濒危物种法案》被列为受威胁物种。本研究分析了来自阿拉斯加威廉王子湾至俄罗斯指挥官群岛14个地点的501份样本在13个微卫星位点（microsatellite loci）的变异特征。结果显示，14个地点间存在高度遗传分化（FST = 0.12），基因流模式符合距离隔离模型（isolation by distance, IBD）（r² = 0.491，p < 0.05）。聚类与排序分析表明，14个采样点可划分为6个地理关联群体，这些群体可能对应残余种群谱系：1）阿拉斯加中南部；2）科迪亚克岛与阿拉斯加半岛北部；3）阿拉斯加半岛南部与布里斯托尔湾；4）阿留申群岛东部；5）阿留申群岛西部；6）指挥官群岛。除阿拉斯加半岛南部与布里斯托尔湾群体外，其余聚类结果与先前定义的种群及管理单元边界高度一致。本研究揭示了显著的遗传种群结构，且总体上与受威胁的阿拉斯加西南部独特种群片段当前的管理策略相契合。