Early warning signals of demographic regime shifts in invading populations
Early warning signals of demographic regime shifts in invading populations
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DOI：
10.1007/s10144-009-0148-2
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发表时间：
2009-03
影响因子：
1.7
通讯作者：
G. Takimoto
中科院分区：
文献类型：
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作者：
G. Takimoto
Allee效应可以引起入侵物种种群丰度的交替稳定状态。入侵种群从低丰度到高丰度的突然爆发可以被视为政权从一个替代状态向另一个替代状态的转变。之前的研究提出了几种类型的预警信号来预测生态系统的制度变化，如受污染的湖泊和半干旱草原。本文从理论上探讨了这些指标在预测入侵人口的人口制度转变方面的潜力。我分析了一个受Allee效应和繁殖压力影响的入侵物种种群动力学的随机微分方程模型。随机模型的扩散近似表明，持续的传播压力使人口制度的转变不可避免，但Allee效应可以延长平均时间，直到制度实际上无限期地转变。为了比较指标的潜力，我检查了纵向种群丰度的标准差、偏度和估计收益率。我发现，随着政权更迭的可能性增加，标准差显示出明显的增加，但偏度和回报率没有显示出明显的趋势。这一结果表明，在入侵种群丰度仍然较低的时期，标准差可能是一个有用的警告信号，用于预测入侵种群即将发生的人口制度转变。
The Allee effect can cause alternative stable states in population abundance of invasive species. Sudden eruption of invading populations from low to high abundance may be viewed as a regime shift from one alternative state to another. Previous research proposed several types of early warning signals to predict regime shifts in ecological systems such as polluted lakes and semiarid grasslands. This paper explores theoretically the potential of such indicators in predicting demographic regime shifts of invading populations. I analyzed a stochastic differential equation model for the population dynamics of an invasive species subject to Allee effects and propagule pressure. Diffusion approximation to the stochastic model suggests that persistent propagule pressure makes demographic regime shifts inevitable, but Allee effects can lengthen the mean time until regime shifts virtually indefinitely. To compare the potential of indicators, I examined standard deviation, skewness, and estimated return rates of longitudinal population abundance. I found that standard deviation showed a distinct increase as regime shifts became more likely, but skewness and return rates showed no clear trends. This result suggests that standard deviation might be a useful warning signal for forecasting an impending demographic regime shift of invading populations during the period when their abundance is still low.