Data from: The coalescent in boundary-limited range expansions

Habitat ranges of most species shift over time, for instance due to climate change, human intervention, or adaptation. These demographic changes often have drastic population genetic effects, such as a stochastic resampling of the gene pool through the "surfing" phenomenon. Most models assume that the speed of range expansions is only limited by the dispersal ability of the colonizing species and its reproductive potential. While such models of "phenotype-limited" expansions apply to species invasions, it is clear that many range expansions are limited rather by the slow motion of habitat boundaries, as driven for instance by global warming. Here, we develop a coalescent model to study the genetic impact of such "boundary-limited" range expansions. Our simulations and analysis show that the resulting loss of genetic diversity is markedly lower than in species invasions if large carrying capacities can be maintained up to the habitat frontier. Counterintuitively, we find that the total loss of diversity does not depend on the speed of the range expansion: Slower expansions have a smaller rate of loss, but also last longer. Boundary-limited range expansions exhibit a characteristic genetic footprint and should therefore be distinguished from range expansions limited only by intrinsic characteristics of the species.多数物种的分布范围会随时间发生位移，驱动因素包括气候变化、人类干预或物种自身的适应性演化。这类种群动态变化往往会对种群遗传产生剧烈影响，例如通过“冲浪（surfing）”现象实现基因库的随机重采样。现有多数模型假设，分布范围扩张的速度仅受定植物种的扩散能力与繁殖潜力限制。这类“表型限制型”扩张模型适用于物种入侵场景，但显然许多分布范围扩张的限速因素实为栖息地边界的缓慢移动——例如全球变暖驱动的边界变化。本研究构建了溯祖模型（coalescent model），以探究此类“边界限制型”分布范围扩张所带来的遗传效应。模拟与分析结果显示，若栖息地前沿可维持较高的环境容纳量（carrying capacity），由此引发的遗传多样性损失将显著低于物种入侵情形。反直觉地，我们发现多样性的总损失与分布范围扩张的速度并无关联：扩张速度越慢，多样性损失的速率越低，但扩张持续的时间也越长。边界限制型分布范围扩张会呈现出特征性的遗传印记，因此应当将其与仅受物种内在特性限制的分布范围扩张区分开来。