Predicting the risk of extinction of species: Impact of negative growth rate and allee effect

Abstract

Predicting the risk of extinction of species is an important aspect in conservation biology. Mathematical models describing the density-dependent per capita growth rates play a predominating role in quantifying the risk of extinction. We used population time series data from Global Population Dynamics Database (GPDD) to predict the threat status of the species using three commonly used growth models, allowing demographic disturbances. The best fitted model from a set of candidate models is used to evaluate the extinction measures. We observed that there are instances where the intrinsic growth rate is negative, which has not been reported earlier. We show that, in such cases, the extinction probability is high, but the species may adopt some strategy that saves them from extinction. The mathematical implications are described in the light of ecological concepts.