Introduced lagomorph produce stronger potential apparent competition in invaded communities than any other species in a similar but native food web

Abstract

Apparent competition is an indirect interaction that can strongly influence ecosystem functioning, altering species populations within the same trophic level. As a new resource, an introduced species can generate strong apparent competition in invaded communities, and even stronger if it becomes the primary resource for consumers. We explore how the European hare (Lepus europaeus), an introduced species in Patagonia, could be generating these stronger effects since many native predators shifted their diets towards them. We constructed and compared two food webs, one in which this primary prey role is played by a native species (the European rabbit, Oryctolagus cuniculus, in Spain) and another in which it is played by an introduced one (the European hare, in Patagonia), to explore their effects in the generation of this indirect interaction. Both were the primary prey in their respective food web and caused the strongest cases of potential apparent competition in each region. Potential apparent competition generated by introduced European hares in Patagonia double that produced by the European rabbit in Spain and was several times higher than any other native prey species. This strong potential apparent competition in an invaded ecosystem highlights the threats that some exotic species may produce, even indirectly.