Invasive herbivores shape food web structure: European rabbit and hare acting as primary prey are conservation challenges

Abstract

As part of the current global change scenario, invasive species have caused many direct impacts on native biodiversity and the interactions among species. European rabbits and hares are two herbivore species that have been introduced worldwide, displacing native species within their trophic level, but also affecting native predators. Both species have become extremely abundant in their exotic distributions, becoming primary prey for many predators, a function that they also play in their native ranges. These relatively new and strong interaction links created with their consumers have the potential to destabilize food webs by precluding the occurrence of weaker links. Here, we have compiled the diet of 32 predator species from three food webs and compared them: one in Europe, where these species are native, and two where they are introduced, in South America and Oceania. We found that these lagomorphs are the primary prey in all study sites, generating a dietary shift of predators in the invaded regions. In all food webs studied, these two preys channeled most of the biomass input towards the higher trophic level, generating the strongest interaction links, affecting the food web configuration and stability. They destabilize food web structure by homogenizing predators' diets, augmenting their niche overlap and web vulnerability. Moreover, rapid population changes of these prey, either natural (e.g., diseases) or anthropic (e.g., control measures), create new conservation challenges for predators and scavengers. This highlights that invasive species can strongly affect interactions among species and it should be considered in management and conservation actions.