Data from: Spatial genetic structure in American black bears (Ursus americanus): female philopatry is variable and related to population history

Previously, American black bears (Ursus americanus) were thought to follow the pattern of female philopatry and male-biased dispersal. However, recent studies have identified deviations from this pattern. Such flexibility in dispersal patterns can allow individuals greater ability to acclimate to changing environments. We explored dispersal and spatial genetic relatedness patterns across ten black bear populations—including long established (historic), with known reproduction >50 years ago, and newly established (recent) populations, with reproduction recorded <50 years ago—in the Interior Highlands and Southern Appalachian Mountains, United States. We used spatially-explicit, individual-based genetic simulations to model gene flow under scenarios with varying levels of population density, genetic diversity, and female philopatry. Using measures of genetic distance and spatial autocorrelation, we compared metrics between sexes, between population types (historic and recent), and among simulated scenarios which varied in density, genetic diversity, and sex-biased philopatry. In empirical populations, females in recent populations exhibited stronger patterns of isolation-by-distance (IBD) than females and males in historic populations. In simulated populations, low density populations had a stronger indication of IBD than medium to high density populations; however, this effect varied in empirical populations. Condition dependent dispersal strategies may permit species to cope with novel conditions and rapidly expand populations. Pattern-process modelling can provide qualitative and quantitative means to explore variable dispersal patterns, and could be employed in other species, particularly to anticipate range shifts in response to changing climate and habitat conditions.

既往研究认为美洲黑熊（Ursus americanus）遵循雌性留居（female philopatry）、雄性偏向扩散（male-biased dispersal）的模式。但近期研究发现了与该模式不符的偏离现象。这类扩散模式的灵活性可使个体具备更强的适应变化环境的能力。我们针对美国内陆高地与阿巴拉契亚山脉南部的10个黑熊种群展开了扩散模式与空间遗传亲缘关系研究，其中包括繁殖记录距今超50年的长期定居（历史种群），以及繁殖记录距今不足50年的新近建立（近期种群）。我们采用空间显性、基于个体的遗传模拟方法，针对种群密度、遗传多样性与雌性留居（female philopatry）水平各异的场景构建基因流模型。借助遗传距离与空间自相关指标，我们比较了不同性别、不同种群类型（历史种群与近期种群）之间的统计量，以及密度、遗传多样性与性别偏向留居水平各异的模拟场景间的差异。在实证种群中，近期种群的雌性个体展现出比历史种群的雌性与雄性个体更强的距离隔离（isolation-by-distance, IBD）模式。在模拟种群中，低密度种群相比中高密度种群展现出更强的距离隔离信号；但该效应在实证种群中存在差异。依赖于环境条件的扩散策略可帮助物种应对新生境并快速实现种群扩张。模式-过程建模可提供定性与定量手段来探究多样化的扩散模式，且可应用于其他物种，尤其可用于预测物种在气候变化与生境变化下的分布范围迁移。