# Allee effect and associated risk of species extinction: An empirical study based on global population dynamics database

### Abstract

The Allee effect represents a density mediated drop in population fitness when they are small in numbers. Its presence increases the likelihood of species extinction if the population numbers fall below a critical threshold, called the Allee threshold. In this manuscript, we have used Global Population Dynamics Database to detect the evidence of Allee effects in natural populations from the time series data. The parameters estimates areobtained under the assumption that, the population fluctuates due to demographic stochasticity. A mathematical model of Allee effect is fitted to estimate the relationship between per capita growth and population size by using the weighted nonlinear least squares method. Thirty one species were identified, where evidence of Allee effect is prevalent. We have also evaluated the extinction measures e.g. probability of extinction, approximation of stationary density, sensitivity of the critical threshold on the probability of extinction.