Université Côte d'Azur, Inria, INRA, CNRS, Sorbonne Université, Biocore team, Sophia Antipolis, France; Department of Mathematics, University of Manitoba, Winnipeg, Canada.
Université Côte d'Azur, Inria, INRA, CNRS, Sorbonne Université, Biocore team, Sophia Antipolis, France.
J Theor Biol. 2019 Jun 21;471:91-107. doi: 10.1016/j.jtbi.2019.03.012. Epub 2019 Mar 20.
Forecasting whether individuals of an introduced population will succeed to establish is a challenge in invasion and conservation biology. The present work aims to decouple the impact of the components of propagule pressure on the time for population establishment in the presence of Allee effects and stochasticity in propagule sizes. The mean first passage time (MFPT) for a population to reach a viable size is used as a measure of the establishment success for the introduction processes involving periodic introductions. By fixing the introduction rate (mean number of introduced individuals per unit time) and varying the period of introduction from small ranges (small and frequent introductions) to large ones (infrequent and large releases), we study the influence of introduction distribution over time. These patterns of introduction are compared in a semi-stochastic model by observing which factors minimize the MFPT from an initially absent population, and hence, ensure the fastest population establishment. We investigate the influence on these minima of the introduction rate, variability in the introduction sizes, and occurrence of catastrophes that temporarily wipe out the population. Whereas most investigated cases show that infrequent and large introductions favor population establishment as expected, small and frequent introductions are preferred when the introduction rate is large and/or the variability in the introduction size is strong. Moreover, we observed counterintuitively that catastrophes strongly increase MFPT at small periods of introduction. In addition, we showed that stochasticity in introduction tends to increase the MFPT except when the introduction rate is small and introductions are evenly spread out in time.
预测引入种群的个体是否能够成功建立是入侵和保护生物学中的一个挑战。本研究旨在分离繁殖体压力的组成部分对具有阿利效应和繁殖体大小随机性的种群建立时间的影响。将种群达到可行大小的平均首次通过时间（MFPT）用作涉及定期引入的引入过程的建立成功的度量。通过固定引入率（单位时间内引入的个体的平均数量）并从小范围（小而频繁的引入）到大范围（不频繁且大量的释放）改变引入周期，我们研究了随时间的引入分布的影响。通过观察哪些因素可以从最初不存在的种群中最小化 MFPT，从而确保种群建立最快，在半随机模型中比较这些引入模式。我们研究了引入率、引入大小的可变性以及暂时消灭种群的灾难发生对这些最小值的影响。虽然大多数研究案例表明，不频繁且大量的引入有利于种群建立，正如预期的那样，但当引入率较大且/或引入大小的可变性较强时，小而频繁的引入更受欢迎。此外，我们观察到反直觉的是，在引入的小周期内，灾难会强烈增加 MFPT。此外，我们还表明，除了引入率较小时且引入时间均匀分布外，引入的随机性往往会增加 MFPT。
