Spatial variation in Allee effects influences patterns of range expansion

Allee effects are thought to slow range expansion and contribute to stable range boundaries. Recent studies have shown Allee effects to vary spatiotemporally due to influences of environmental heterogeneity on population processes. Gradients in Allee effects might occur as a species' range approaches suboptimal conditions while expanding into new territory. Allee effects could exhibit patchiness if drivers of positive density dependence (e.g., mate finding rates) are influenced by habitat patchiness. However, theoretical studies have largely assumed Allee effects to be spatially constant. The goal of this study was to evaluate how spatiotemporal patterns of range expansion respond to spatial variations in Allee effects. We simulated spread in landscapes that differed in the spatial configuration and range of Allee thresholds. We compared spread with a constant Allee effect to spread in landscapes where the Allee threshold varied along a gradient or in a patchy fashion. Landscape configu...

Allee效应（Allee effects）被认为会减缓物种分布范围的扩张，并促成稳定的分布范围边界。近期研究显示，受环境异质性对种群过程的影响，Allee效应会发生时空变异。当物种向新领地扩张且其分布范围趋近次优环境条件时，Allee效应可能呈现梯度分布特征。若正密度依赖的驱动因素（如配偶搜寻速率）受到生境斑块性的影响，Allee效应则可能表现出斑块性特征。然而，现有理论研究大多假设Allee效应在空间上恒定不变。本研究旨在评估物种分布范围扩张的时空格局如何响应Allee效应的空间变异。我们在空间配置与Allee阈值（Allee threshold）范围各不相同的景观中模拟了物种分布范围的扩散过程，并将恒定Allee效应下的扩散过程，与Allee阈值沿梯度变化或呈斑块状分布的景观中的扩散过程进行了对比。景观配置……