Abstract

The Allee threshold, the critical population density separating growth from decline in populations experiencing strong Allee effects, can vary over space and time but few empirical studies have examined this variation. A lack of geographically extensive, long-term studies on low density population dynamics makes studying variability in Allee effects difficult. We used North American gypsy moth population data from 1996 to 2016 to quantify Allee thresholds in 11 regions of the invasion front. Allee thresholds spanned a continuum from being undetectable due to strong population growth at all densities, to being unmeasurable because populations declined across all densities. The lag-1 temporal autocorrelation in Allee thresholds tended to be negative and spatial synchrony in Allee thresholds extended no further than adjacent regions. This work furthers understanding of spatiotemporal variation in Allee effects using extensive empirical data at the range edge of an invasive insect.

中文翻译：

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吉卜赛蛾种群入侵的Allee效应时空变化

摘要

Allee阈值（临界人口密度，将增长与经历强烈Allee效应的人口下降隔离开来）可以随时间和空间变化，但是很少有实证研究研究这种变化。缺乏对低密度种群动态的地理上广泛的长期研究，使得研究Allee效应的变异性变得困难。我们使用1996年至2016年的北美吉普赛蛾种群数据来量化入侵前沿11个地区的Allee阈值。从所有密度的人口增长强劲到无法检测到，由于各种密度的人口下降，Allee的阈值跨越了一个连续的过程。Allee阈值中的lag-1时间自相关趋于为负，Allee阈值中的空间同步性延伸的范围不超过相邻区域。