Data from: How far is too close? Restricted, sex-biased dispersal in black-capped vireos

Understanding the interplay of dispersal and how it translates into gene flow is key to understanding population processes, and especially so for endangered species occupying fragmented habitats. In migratory songbirds, there is evidence that long-distance movement capabilities are not highly related to observed dispersal. Our objectives were to 1) define the fine-scale spatial genetic structure in the endangered black-capped vireos to shed light on dispersal patterns, and 2) to relate dispersal dynamics to overall population genetic structure using a simulation approach. We sampled 160 individuals over two years to describe the fine-scale genetic structuring, and used this information to model scenarios to compare with actual data on change in population structuring over a 100-year interval. We found that black-capped vireo exhibit male-philopatry, and restricted dispersal distances, relative to females. Our simulations support a sex-biased dispersal model. Additionally, we find that fragmentation related changes in rates of dispersal might be a likely cause for increasing levels of population structure over a 100-year period. We show that restricted dispersal can explain population structuring in this species, and that changes in dispersal rates due to fragmentation may be a continuing threat to genetic viability in this species.厘清扩散（dispersal）作用及其转化为基因流（gene flow）的内在关联，是理解种群过程的核心要义，对于栖息于破碎化生境的濒危物种而言尤为关键。针对迁徙鸣禽的研究显示，其长距离移动能力与实际观测到的扩散行为并无显著相关性。本研究的目标分为两点：其一，明确濒危物种黑顶绿鹃（black-capped vireo）的精细空间遗传结构（fine-scale spatial genetic structure），以揭示其扩散模式；其二，通过模拟方法（simulation approach），将扩散动态与整体种群遗传结构相关联。本研究耗时两年采集了160个个体的样本以解析其精细遗传结构，并基于该数据构建模拟情景，与百年尺度下种群结构变化的实测数据开展对比分析。研究发现，相较于雌性个体，黑顶绿鹃存在雄性恋巢（male-philopatry）行为，且扩散距离受限。本研究的模拟结果验证了性别偏向性扩散（sex-biased dispersal）模型的合理性。此外，本研究发现，生境破碎化引发的扩散速率改变，或为百年尺度下种群结构分化程度加剧的核心诱因。本研究证实，受限扩散能够合理解释该物种的种群结构特征，而由生境破碎化导致的扩散速率变化，或持续威胁该物种的遗传存续能力（genetic viability）。