Consumer demand for plant and animal products threatens many populations with
extinction. The anthropogenic Allee effect (AAE) proposes that such extinctions
can be caused by prices for wildlife products increasing with species rarity.
This price-rarity relationship creates financial incentives to extract the last
remaining individuals of a population, despite higher search and harvest costs.
The AAE has become a standard approach for conceptualizing the threat of
economic markets on endangered species. Despite its potential importance for
conservation, AAE theory is based on a simple graphical model with limited
analysis of possible population trajectories. By specifying a general class of
functions for price-rarity relationships, we show that the classic theory can
understate the risk of species extinction. AAE theory proposes that only
populations below a critical Allee threshold will go extinct due to increasing
price-rarity relationships. Our analysis shows that this threshold can be much
higher than the original theory suggests, depending on initial harvest effort.
More alarmingly, even species with population sizes above this Allee threshold,
for which AAE predicts persistence, can be destined to extinction. Introducing
even a minimum price for harvested individuals, close to zero, can cause large
populations to cross the classic anthropogenic Allee threshold on a trajectory
towards extinction. These results suggest that traditional AAE theory may give
a false sense of security when managing large harvested populations
