Kidd Monica G, Friesen Vicki L
Department of Biology, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
Evolution. 1998 Aug;52(4):1158-1168. doi: 10.1111/j.1558-5646.1998.tb01842.x.
We surveyed population-level sequence variation in part of the mitochondrial control region for three species including eight subspecies of Cepphus guillemots (Charadriiformes: Alcidae) to test specific predictions about mechanisms of population differentiation. We found that sequences of spectacled guillemots (C. carbo) were more closely related to those of pigeon guillemots (C. columba; both found in the Pacific Ocean) than to those of black guillemots (C. grylle; Arctic and Atlantic Oceans), despite dissimilarities in plumage between spectacled guillemots and the other species. Distributions of species and timing of divergence events suggest that speciation involved allopatric and microallopatric populations isolated by Pleistocene glaciers. Control region sequences were significantly differentiated among populations within species and suggest that gene flow is low; however, populations are probably not in genetic equilibrium, so these results probably reflect historical isolation of colonies. In contrast, phylogenetic relationships among sequences within species were poorly resolved, probably because of a combination of incomplete lineage sorting and contemporary gene flow. Indices of genetic diversity provided no suggestion of recent bottlenecks in most populations, although two populations apparently underwent recent severe bottlenecks. Genetic divergence among populations was not correlated with geographic distance, which argues against isolation by distance. Results of these analyses, combined with breeding distributions and timing of divergence events, suggest that populations diverged during isolation in glacial refugia. Our results are consistent with earlier hypotheses posed by Storer and Udvardy.
我们对包括8个亚种的厚嘴海鸦（鸻形目：海雀科）在内的3个物种的线粒体控制区部分进行了群体水平的序列变异调查，以检验关于群体分化机制的具体预测。我们发现，眼镜海鸦（C. carbo）的序列与鸽海鸦（C. columba；均见于太平洋）的序列比与黑海鸦（C. grylle；见于北极和大西洋）的序列关系更密切，尽管眼镜海鸦与其他物种在羽毛上存在差异。物种分布和分化事件的时间表明，物种形成涉及被更新世冰川隔离的异域和微异域种群。控制区序列在物种内的群体间有显著差异，表明基因流较低；然而，群体可能并未处于遗传平衡状态，因此这些结果可能反映了群体的历史隔离。相比之下，物种内序列之间的系统发育关系解析度较差，这可能是由于不完全谱系分选和当代基因流共同作用的结果。遗传多样性指数并未表明大多数群体近期经历过瓶颈效应，尽管有两个群体显然近期经历过严重瓶颈。群体间的遗传分化与地理距离无关，这与距离隔离的观点相悖。这些分析结果，结合繁殖分布和分化事件的时间，表明群体是在冰川避难所隔离期间发生分化的。我们的结果与斯托勒和乌德瓦迪早期提出的假设一致。
