Are threatened species important for glueing interaction networks together?

Abstract

Biotic interactions are a critical element for the functioning and the stability of ecosystems, yet anthropogenic pressures can significantly disrupt these networks of interacting species. While species-focused conservation is central to most conservation policy, it is also vital to identify the interactions at risk and the ones that play a disproportionate role in glueing communities together. Here we assess the importance of species for ecological network integrity and the risk of loss of interactions that is brought by species loss in a global predator-prey network comprising 877 mammal species. We calculated the importance of species and their interactions using network centrality analyses. The risk of loss of interactions was determined by quantifying the extinction risk of each pair of interacting species. Additionally, we examined whether specific traits or phylogenetic history influenced both extinction risk and species importance. We found that extinction risk is unrelated to species’ importance in the network. We also showed that the most important interactions are at least partially at risk of being lost. Moreover, important and threatened species showed higher ecological distinctiveness, but similar low evolutionary distinctiveness. We emphasise that conservation strategies should consider the contributions of both threatened and non-threatened species to ecological networks, acknowledging the vital roles they play for ecosystem stability and function.