Data from: Inferring the timing of long-distance dispersal between rail metapopulations using genetic and isotopic assignments

The stochastic and infrequent nature of long-distance dispersal often makes it difficult to detect. We quantified the frequency, distance, and timing of long-distance dispersal in a non-migratory, secretive wetland bird, the California black rail (Laterallus jamaicensis coturniculus), between an inland and a coastal metapopulation separated by greater than 100 km. Using 15 microsatellites in conjunction with stable carbon, nitrogen, and sulfur isotopes, we classified rails as: residents of their capture population, recent migrants that dispersed to their capture population less than one year before capture, established migrants that dispersed to their capture population more than one year before capture, and seasonal migrants that dispersed away from their capture population to forage, but returned the next season. Most rails (195 of 204 or 95.6%) were classified as residents, but we detected two established migrants that had moved >100 km more than a year before capture. Seven rails appeared to be seasonal migrants, but comparisons of feather isotope values with isotope values from wetland soils indicated that the isotope values in the feathers of these rails likely resulted from natural environmental variation (e.g., source element effects) rather than long-distance dispersal of individuals. Thus, these seven rails were most likely misassigned by isotopic population assignments due to small-scale variation in the isoscape. Using genetic data in conjunction with isotopic data allowed us to not only infer the timing of long-distance dispersal events, but to successfully track long-distance movements of non-migratory rails between metapopulations even when environmental variation of isotopes occurred across small spatial scales.长距离扩散（long-distance dispersal）具有随机性与低发生频率的特点，往往难以被检测到。本研究以一种非迁徙性、行踪隐秘的湿地鸟类——加州黑秧鸡（Laterallus jamaicensis coturniculus）为研究对象，在间隔超100km的内陆与沿海集合种群（metapopulation）之间，量化分析了其长距离扩散的发生频率、扩散距离与时间节点。研究借助15个微卫星标记（microsatellites）结合稳定碳、氮、硫同位素，将捕获的加州黑秧鸡划分为四类：定居于捕获种群的个体、捕获前一年内扩散至该捕获种群的新近迁入个体、捕获前一年以上扩散至该捕获种群的已定居迁入个体，以及为觅食离开捕获种群并于次年返回的季节性移动个体。本次研究共纳入204只加州黑秧鸡，其中195只（占比95.6%）被归类为定居个体，仅检测到2只为捕获前一年以上扩散距离超过100km的已定居迁入个体。另有7只个体看似为季节性移动个体，但通过将其羽毛同位素值与湿地土壤同位素值对比分析发现，这些个体羽毛中的同位素信号更可能源自自然环境变异（如源元素效应（source element effects）），而非个体发生的长距离扩散。因此，这7只个体大概率是因同位素景观（isoscape）存在小尺度空间变异，被同位素种群归属分析误判的个体。结合遗传数据与同位素数据开展的分析，不仅使我们得以推断长距离扩散事件的发生时间，还能在同位素环境变化仅存在小尺度空间差异的情况下，成功追踪非迁徙性加州黑秧鸡在集合种群间的长距离移动情况。