Burg Theresa M, Gaston Anthony J, Winker Kevin, Friesen Vicki L
Department of Biology, Queen's University, Kingston, ON, Canada K7L 3N6.
Mol Ecol. 2005 Oct;14(12):3745-55. doi: 10.1111/j.1365-294X.2005.02710.x.
Post-Pleistocene avian colonization of deglaciated North America occurred from multiple refugia, including a coastal refugium in the northwest. The location of a Pacific Coastal refugium is controversial; however, multiple lines of evidence suggest that it was located near the Queen Charlotte Islands (also known as Haida Gwaii). The Queen Charlotte Islands contain a disproportionately large number of endemic plants and animals including the Steller's jay Cyanocitta stelleri carlottae. Using five highly variable microsatellite markers, we studied population structure among eight populations of Steller's jay (N = 150) from geographical areas representing three subspecies in western North America: C. s. carlottae, C. s. stelleri and C. s. annectens. Microsatellite analyses revealed genetic differentiation between each of the three subspecies, although more extensive sampling of additional C. s. annectens populations is needed to clarify the level of subspecies differentiation. High levels of population structure were found among C. s. stelleri populations with significant differences in all but two pairwise comparisons. A significant isolation by distance pattern was observed amongst populations in the Pacific Northwest and Alaska. In the C. s. carlottae population, there was evidence of reduced genetic variation, higher number of private alleles than northern C. s. stelleri populations and higher levels of divergence between Queen Charlotte Island and other populations. We were unable to reject the hypothesis that the Queen Charlotte Islands served as a refugium during the Pleistocene. Steller's jay may have colonized the Queen Charlotte Islands near the end of the last glaciation or persisted throughout the Pleistocene, and this subspecies may thus represent a glacial relic. The larger number of private alleles, despite reduced genetic variation, morphological distinctiveness and high divergence from other populations suggests that the Queen Charlotte Island colonization pre-dates that of the mainland. Furthermore, our results show rapid divergence in Steller's jay populations on the mainland following the retreat of the ice sheets.
更新世之后，鸟类从多个避难所开始在北美洲冰川消退地区定居，其中包括西北部的一个沿海避难所。太平洋沿岸避难所的位置存在争议；然而，多条证据表明它位于夏洛特皇后群岛（也称为海达瓜伊）附近。夏洛特皇后群岛拥有数量不成比例的大量特有动植物，包括冠蓝鸦夏洛特皇后群岛亚种（Cyanocitta stelleri carlottae）。我们使用五个高度可变的微卫星标记，研究了北美洲西部代表三个亚种的地理区域中八个冠蓝鸦种群（N = 150）的种群结构：C. s. carlottae、C. s. stelleri和C. s. annectens。微卫星分析揭示了三个亚种之间的遗传分化，不过需要对更多的C. s. annectens种群进行更广泛的采样，以阐明亚种分化的程度。在C. s. stelleri种群中发现了高水平的种群结构，除了两个成对比较外，所有比较均存在显著差异。在太平洋西北部和阿拉斯加的种群中观察到显著的距离隔离模式。在C. s. carlottae种群中，有证据表明遗传变异减少，私有等位基因数量比北部的C. s. stelleri种群更多，并且夏洛特皇后群岛与其他种群之间的分化程度更高。我们无法拒绝夏洛特皇后群岛在更新世期间作为避难所的假设。冠蓝鸦可能在末次冰期即将结束时定居在夏洛特皇后群岛，或者在整个更新世都一直存在，因此这个亚种可能代表了一个冰川遗迹。尽管遗传变异减少，但私有等位基因数量较多、形态独特以及与其他种群的高度分化表明，夏洛特皇后群岛的定居早于大陆。此外，我们的结果表明，冰盖消退后，大陆上的冠蓝鸦种群迅速分化。
