Synergistic effects of habitat fragmentation and hunting on the extinction risk of neotropical primates

Habitat fragmentation and overexploitation of natural resources are the most prevalent and severe threats to biodiversity in tropical forests. Several studies have estimated the effect of these threats on species extinction risk, however the effect resulting from their interaction remains poorly understood. Here, we assess whether and how habitat area, fragmentation, and hunting can synergistically affect the extinction risk of neotropical primates (Platyrrhine). We use a Random Forest model to estimate the Red List extinction risk category of 147 primate species based on their biological traits and the environmental predictors they are exposed to. We find that environmental variables are better predictors of extinction risk than biological traits, and that hunting and fragmentation interact creating synergistic feedback that lead to higher extinction risk than when considered in isolation. We also show that the effect of environmental predictors is mediated by biological traits, with large species being sensitive to habitat area and fragmentation, and frugivorous species more threatened by hunting. Our results increase the understanding of potentially interactive effects between different threats, habitat area and species traits, supporting the idea that multiple threats can reinforce each other and should be thus addressed simultaneously in conservation agendas.