School of Natural Resources and Agricultural Sciences, University of Alaska Fairbanks, Palmer, AK 99645, USA.
J Hered. 2009 Nov-Dec;100(6):681-90. doi: 10.1093/jhered/esp061. Epub 2009 Jul 24.
Polar bears (Ursus maritimus) are unique among bears in that they are adapted to the Arctic sea ice environment. Genetic data are useful for understanding their evolution and can contribute to management. We assessed parentage and relatedness of polar bears in the southern Beaufort Sea, Alaska, with genetic data and field observations of age, sex, and mother-offspring and sibling relationships. Genotypes at 14 microsatellite DNA loci for 226 bears indicate that genetic variation is comparable to other populations of polar bears with mean number of alleles per locus of 7.9 and observed and expected heterozygosity of 0.71. The genetic data verified 60 field-identified mother-offspring pairs and identified 10 additional mother-cub pairs and 48 father-offspring pairs. The entire sample of related and unrelated bears had a mean pairwise relatedness index (r(xy)) of approximately zero, parent-offspring and siblings had r(xy) of approximately 0.5, and 5.2% of the samples had r(xy) values within the range expected for parent-offspring. Effective population size (N(e) = 277) and the ratio of N(e) to total population size (N(e)/N = 0.182) were estimated from the numbers of reproducing males and females. N(e) estimates with genetic methods gave variable results. Our results verify and expand field data on reproduction by females and provide new data on reproduction by males and estimates of relatedness and N(e) in a polar bear population.
北极熊（Ursus maritimus）是熊科动物中唯一适应北极海冰环境的物种。遗传数据有助于了解其进化过程，并能为管理提供参考。我们利用遗传数据和对年龄、性别以及母-仔和同胞关系的野外观察，评估了阿拉斯加波弗特海南部北极熊的亲子关系和亲缘关系。对 226 只北极熊的 14 个微卫星 DNA 座的基因型分析表明，遗传变异与其他北极熊种群相当，每个位点的平均等位基因数为 7.9，观察到的和预期的杂合度分别为 0.71。遗传数据验证了 60 对野外鉴定的母-仔对，并确定了另外 10 对母-幼仔对和 48 对父-仔对。所有相关和不相关的熊的平均亲缘关系指数（r(xy)）约为零，亲子和同胞的 r(xy)约为 0.5，5.2%的样本的 r(xy)值在亲子关系的预期范围内。繁殖雄性和雌性的数量估算出有效种群大小（N(e) = 277）和 N(e)与总种群大小的比例（N(e)/N = 0.182）。遗传方法的 N(e)估计结果存在差异。我们的研究结果验证并扩展了雌性繁殖的野外数据，并提供了雄性繁殖以及亲缘关系和 N(e)的新数据。
