Dispersal may enable persistence of fruit flies suffering from the Allee effect and scramble competition

Larvae of drosophilid fruit flies experience an Allee effect: they cannot develop into adults at low densities. In addition, the larvae suffer from a scramble type of competition. The Allee effect and scramble competition create a lower as well as an upper bound to the number of larvae that can successfully develop on a resource. The common resources for drosophilid fruit flies are ephemeral and patchily distributed. Therefore, a non-dispersing fruit fly population is doomed to go extinct, because the population number almost certainly crosses the lower or upper bound at some point in time. Our study shows that dispersal is one of the mechanisms that might help to surmount these effects and ensure long-term persistence of the fruit fly population.