The competitive dynamics of metapopulations subject to the Allee-like effect

It is well recognized that individuals of many species can benefit from the presence of conspecifics, a concept broadly referred to as the Allee effect. At the metapopulation level, there is an analogous but essentially different phenomenon called the Allee-like effect that leads to metapopulation extinction thresholds at low habitat occupancy. But so far not adequate attention has been paid to this phenomenon. In this paper, the Allee-like effect is introduced into a metapopulation model of one species and also that of a three-state two-species competitive system. Phase plane analysis is used to investigate the dynamics of these models. We demonstrate that the Allee-like effect alone could lead to multiple stable states in three-state two-species competitive systems at the metapopulation level, and the number of stable states decrease as the Allee-like effect becomes more severe. Severe Allee-like effects may make coexistence impossible and may even lead to the extinction of both species even if their initial habitat occupancies are high and suitable habitats are enough. It is especially noticeable that depending on their initial conditions one species may exclude the other one that subjects to a weaker Allee-like effect than the former, while the second species always excludes the first one when both species are assumed to be in the absence of the Allee-like effect. We also investigate the habitat destructive effect on the Allee-like system mentioned above. Research indicates that the existence of the Allee-like effect makes a metapopulation more susceptible to habitat destruction. All in all, the Allee-like effect is probably a destabilizing factor that, together with habitat destruction, would affect the continuous existence of species. These conclusions may have important implications for conservation and metacommunity organization.