Data from: Genetic variation and seasonal migratory connectivity in Wilson’s warblers (Wilsonia pusilla): species-level differences in nuclear DNA between western and eastern populations

There is growing interest in understanding patterns of seasonal migratory connectivity between breeding and wintering sites, both because differences in migratory behavior can be associated with population differentiation and because knowledge of migratory connectivity is essential for understanding the ecology, evolution, and conservation of migratory species. We present the first broad survey of geographic variation in the nuclear genome of breeding and wintering Wilson’s warblers (Wilsonia pusilla), which have previously served as a research system for the study of whether genetic markers and isotopes can reveal patterns of migratory connectivity. Using 153 samples surveyed at up to 257 variable amplified fragment length polymorphism (AFLP) markers, we show that Wilson’s warblers consist of highly distinct western and eastern breeding groups, with all winter samples grouping with the western breeding group. Within the west there is weak geographic differentiation, at a level insufficient for use in assignment of wintering samples to specific areas. The distinctiveness of western and eastern genetic groups, with no known intermediates, strongly suggests that these two groups are cryptic species. Analysis of mitochondrial cytochrome b sequence variation shows that the estimated coalescence time between western and eastern clades is roughly 2.3 million years ago, a surprisingly old time of divergence that is more typical of distinct species than of subspecies. Given their morphological similarity but strong genetic differences, western and eastern Wilson’s warblers present a likely case of association between divergence in migratory behavior and the process of speciation.学界对繁殖地与越冬地间的季节性迁徙连通模式的研究兴趣与日俱增：一方面，迁徙行为差异可能与种群分化相关；另一方面，明晰迁徙连通性对于理解迁徙物种的生态学、演化及保护工作至关重要。本研究首次针对繁殖与越冬期的威尔逊莺（Wilsonia pusilla）的核基因组地理变异展开系统性调查——此前该物种曾被用作探究遗传标记与同位素能否揭示迁徙连通模式的研究体系。本研究通过对153份样本的至多257个可变扩增片段长度多态性（amplified fragment length polymorphism, AFLP）标记进行分型分析，结果显示威尔逊莺可分为分化极为显著的西部繁殖种群与东部繁殖种群，且所有越冬样本均聚类于西部繁殖种群分支。西部种群内部仅存在微弱的地理分化，其分化程度不足以将越冬样本准确归属至特定繁殖区域。西部与东部遗传类群间分化显著，且尚未发现中间过渡类群，这强烈表明二者属于隐存种。对线粒体细胞色素b序列变异的分析显示，西部与东部演化支的溯祖时间约为230万年前，这一分化时间早得异乎寻常，更符合独立物种间的分化特征，而非亚种间的分化水平。尽管西部与东部威尔逊莺在形态上极为相似，但二者遗传差异显著，这为迁徙行为分化与物种形成过程间的关联提供了极具说服力的研究案例。