Paetkau D, Shields G F, Strobeck C
Department of Biological Sciences, University of Alberta, Edmonton, Canada.
Mol Ecol. 1998 Oct;7(10):1283-92. doi: 10.1046/j.1365-294x.1998.00440.x.
The brown bears of coastal Alaska have been recently regarded as comprising from one to three distinct genetic groups. We sampled brown bears from each of the regions for which hypotheses of genetic uniqueness have been made, including the bears of the Kodiak Archipelago and the bears of Admiralty, Baranof and Chichagof (ABC) Islands in southeast Alaska. These samples were analysed with a suite of nuclear microsatellite markers. The 'big brown bears' of coastal Alaska were found to be part of the continuous continental distribution of brown bears, and not genetically isolated from the physically smaller 'grizzly bears' of the interior. By contrast, Kodiak brown bears appear to have experienced little or no genetic exchange with continental populations in recent generations. The bears of the ABC Islands, which have previously been shown to undergo little or no female-mediated gene flow with mainland populations, were found not to be genetically isolated from mainland bears. The data from the four insular populations indicate that female and male dispersal can be reduced or eliminated by water barriers of 2-4 km and 7 km in width, respectively.
阿拉斯加沿海的棕熊最近被认为由一到三个不同的基因群体组成。我们从每个提出基因独特性假设的地区采集了棕熊样本，包括科迪亚克群岛的熊以及阿拉斯加东南部金钟岛、巴拉诺夫岛和奇恰戈夫岛（ABC群岛）的熊。这些样本用一组核微卫星标记进行了分析。结果发现，阿拉斯加沿海的“大型棕熊”是棕熊连续大陆分布的一部分，在基因上与内陆体型较小的“灰熊”并无隔离。相比之下，科迪亚克棕熊在近代似乎很少或几乎没有与大陆种群进行基因交流。此前已表明，ABC群岛的熊与大陆种群之间很少或几乎没有雌性介导的基因流动，但发现它们在基因上并未与大陆熊隔离。来自这四个岛屿种群的数据表明，宽度为2 - 4公里和7公里的水域屏障分别可以减少或消除雌性和雄性的扩散。
