The ecological role of the European rabbit in the Magellanic/Fuegian ecosystem of southernmost Chile

Abstract

The European rabbit has invaded numerous ecosystems around the world, but rarely steppes. We studied the food web in the Magallanes region of southernmost Chile, where the rabbit is now a key player, interacting with species at different trophic levels. Because the rabbit is currently well embedded in the Magellanic/Fuegian ecosystem, especially in the steppe, any changes in its local abundance can spread out through trophic interactions and generate unwanted impacts in the regional food web. We used a multi-species trophic network approach and built the food web of the Magellanic/Fuegian steppe based on the rabbit interspecific relationships through a bibliographic review. We evaluated its topological properties and performed a species extinction analysis to assess the relative importance of the rabbit. The network has 222 nodes (64% native, 12% exotic, and 23% mixed), 576 links, and a connectance of 0.011. The rabbit was the most connected node of the network, had the second largest dietary breadth, and was the sixth with the highest number of predatory species. Our results suggest that rabbit control could trigger several ecological impacts on other regional species, such as releasing herbivory pressure on plants of various genera. In addition, by reducing or removing a staple prey resource for predators, they may decrease their abundance or change their diet to alternative prey, generating unexpected effects. The multi-species network approach could be a complementary tool to apply a more holistic management of the rabbit, which would allow the identification of non-target species that should be monitored when control is being applied, and thereby generate early warnings against unwanted impacts.