Data from: Fitness declines toward range limits and local adaptation to climate affect dispersal evolution during climate-induced range shifts

Dispersal ability will largely determine whether species track their climatic niches during climate change, a process especially important for populations at contracting (low-latitude/low-elevation) range limits that otherwise risk extinction. We investigate whether dispersal evolution at contracting range limits is facilitated by two processes that potentially enable edge populations to experience and adjust to the effects of climate deterioration before they cause extinction: (i) climate-induced fitness declines towards range limits and (ii) local adaptation to a shifting climate gradient. We simulate a species distributed continuously along a temperature gradient using a spatially explicit, individual-based model. We compare range-wide dispersal evolution during climate stability vs. directional climate change, with uniform fitness vs. fitness that declines towards range limits (RLs), and for a single climate genotype vs. multiple genotypes locally adapted to temperature. During climate stability, dispersal decreased towards RLs when fitness was uniform, but increased when fitness declined towards RLs, due to highly dispersive genotypes maintaining sink populations at RLs, increased kin selection in smaller populations, and an emergent fitness asymmetry that favoured dispersal in low-quality habitat. However, this initial dispersal advantage at low-fitness RLs did not facilitate climate tracking, as it was outweighed by an increased probability of extinction. Locally adapted genotypes benefited from staying close to their climate optima; this selected against dispersal under stable climates but for increased dispersal throughout shifting ranges, compared to cases without local adaptation. Dispersal increased at expanding RLs in most scenarios, but only increased at the range centre and contracting RLs given local adaptation to climate.扩散能力在很大程度上决定了物种能否在气候变化过程中追踪其气候生态位，这一过程对于分布范围收缩（低纬度/低海拔）的边缘种群尤为关键，此类种群若无法完成生态位追踪则将面临灭绝风险。本研究旨在探究分布范围收缩边缘的扩散演化，是否可通过两类过程得以促进：这两类过程可使边缘种群在气候恶化引发灭绝前，感知并适应其影响：(i) 气候诱导下随分布范围边缘（range limits, RLs）逐渐降低的适合度；(ii) 对动态气候梯度的本地适应。本研究使用空间显式基于个体的模型（individual-based model），模拟了沿温度梯度连续分布的物种种群。本研究对比了多种情境下的全分布范围扩散演化：包括气候稳定与定向气候变化两种气候场景，适合度均匀分布与随分布范围边缘逐渐降低两种适合度模式，以及单一气候基因型与多个适应温度的本地基因型两种遗传背景。在气候稳定场景下，当适合度均匀分布时，扩散能力随分布范围边缘逐渐降低；而当适合度随分布范围边缘递减时，扩散能力则随边缘升高。这一现象源于三方面原因：高扩散基因型可维持分布边缘的汇种群、小种群内亲缘选择作用增强，以及低质量生境中偏好扩散的涌现性适合度不对称性。然而，这种在低适合度分布边缘出现的初始扩散优势，并未促进气候生态位追踪，因为其带来的灭绝风险上升抵消了这一优势。相较于无本地适应的情境，具备本地适应的基因型可通过保留在其气候最适生境中获益：这一选择压力在气候稳定场景下会抑制扩散，但在动态变化的分布范围中则会选择提升扩散能力。在多数情境下，分布范围扩张边缘的扩散能力会有所提升；而仅当存在气候本地适应时，分布范围中心与收缩边缘的扩散能力才会上升。