PT  - JOURNAL ARTICLE
AU  - Gregory Roth
AU  - Sebastian J. Schreiber
TI  - Pushed Beyond the Brink: Allee Effects, Environmental Stochasticity, and Extinction
AID  - 10.1101/004887
DP  - 2014 Jan 01
TA  - bioRxiv
PG  - 004887
4099  - http://biorxiv.org/content/early/2014/09/02/004887.short
4100  - http://biorxiv.org/content/early/2014/09/02/004887.full
AB  - To understand the interplay between environmental stochasticity and Allee effects, we analyze persistence, asymptotic extinction, and conditional persistence for stochastic difference equations. Our analysis reveals that persistence requires that the geometric mean of fitness at low densities is greater than one. When this geometric mean is less than one, asymptotic extinction occurs with high probability for low initial population densities. Additionally, if the population only experiences positive density-dependent feedbacks, conditional persistence occurs provided the geometric mean of fitness at high population densities is greater than one. However, if the population experiences both positive and negative density-dependent feedbacks, conditional persistence only occurs if environmental fluctuations are sufficiently small. We illustrate counter-intuitively that environmental fluctuations can increase the probability of persistence when populations are initially at low densities, and can cause asymptotic extinction of populations experiencing intermediate predation rates despite conditional persistence occurring at higher predation rates.