Toews David P L, Heavyside Julian, Irwin Darren E
Department of Zoology and Biodiversity Research Centre University of British Columbia Vancouver BC Canada.
Cornell Lab of Ornithology Cornell University Ithaca NY USA.
Ecol Evol. 2017 Jul 18;7(17):6649-6658. doi: 10.1002/ece3.3222. eCollection 2017 Sep.
Long-distance migration is a behavior that is exhibited by many animal groups. The evolution of novel migration routes can play an important role in range expansions, ecological interactions, and speciation. New migration routes may evolve in response to selection in favor of reducing distance between breeding and wintering areas, or avoiding navigational barriers. Many migratory changes are likely to evolve gradually and are therefore difficult to study. Here, we attempt to connect breeding and wintering populations of myrtle warblers () to better understand the possible evolution of distinct migration routes within this species. Myrtle warblers, unlike most other warblers with breeding ranges primarily in eastern North America, have two disjunct overwintering concentrations-one in the southeastern USA and one along the Pacific Coast-and presumably distinct routes to-and-from these locations. We studied both myrtle and Audubon's warblers () captured during their spring migration along the Pacific Coast, south of the narrow region where these two taxa hybridize. Using stable hydrogen isotopes and biometric data, we show that those myrtle warblers wintering along the southern Pacific Coast of North America are likely to breed at high latitudes in Alaska and the Yukon rather than in Alberta or further east. Our interpretation is that the evolution of this wintering range and migration route along the Pacific Coast may have facilitated the breeding expansion of myrtle warblers into northwestern North America. Moreover, these data suggest that there may be a migratory divide within genetically similar populations of myrtle warblers.
长途迁徙是许多动物群体所表现出的一种行为。新迁徙路线的进化在分布范围扩张、生态相互作用和物种形成中可能发挥重要作用。新的迁徙路线可能会因有利于缩短繁殖地和越冬地之间距离或避开导航障碍的选择而进化。许多迁徙变化可能是逐渐演变的，因此难以研究。在这里，我们试图将桃金娘林莺（）的繁殖种群和越冬种群联系起来，以更好地了解该物种内不同迁徙路线的可能进化情况。与大多数繁殖范围主要在北美东部的其他林莺不同，桃金娘林莺有两个不连续的越冬集中地——一个在美国东南部，另一个在太平洋沿岸——并且往返于这些地点的路线可能不同。我们研究了在这两个分类群杂交的狭窄区域以南沿着太平洋海岸春季迁徙期间捕获的桃金娘林莺和奥杜邦林莺（）。利用稳定氢同位素和生物特征数据，我们表明那些在北美太平洋海岸南部越冬的桃金娘林莺可能在阿拉斯加和育空地区的高纬度地区繁殖，而不是在艾伯塔省或更东部。我们的解释是，沿着太平洋海岸的这个越冬范围和迁徙路线的进化可能促进了桃金娘林莺向北美西北部的繁殖扩张。此外，这些数据表明在基因相似的桃金娘林莺种群中可能存在迁徙分界线。
