The intrinsic and extrinsic drivers of extinction risk in lemurs (Lemuroidea)

Understanding why some species are more susceptible to extinction than others is critical for implementing effective conservation strategies. Phylogenetic comparative methods (PCMs) have been used to understand the drivers of extinction risk, and are most effective when applied to an entire lineage. Lemurs are a monophyletic group that evolved in Madagascar in relative isolation over millions of years, representing a unique and diverse lineage that provides an excellent case study for the drivers of extinction risk. We investigated the drivers of extinction risk in lemurs using intrinsic (species' traits) and extrinsic (environmental) variables related to ecology, life-history, and biogeography. We evaluated the tempo and mode of trait evolution and used PCMs to examine correlations between traits and extinction risk. We used models of trait evolution and historic and future climate data to predict how lemurs will fare under climate change. The predominant drivers of extinction risk in lemurs were diurnal activity and longevity, which were positively and negatively associated with extinction risk, respectively. Body size, as well as temperature mean and temperature variance across a species' range, were also predictors of risk. We found no evidence for evolution punctuated by short periods of rapid change in response to environmental shifts or other factors (punctuated equilibria), suggesting that traits will not evolve to track Madagascar's changing climate. These results may inform conservation strategies in Madagascar by differentiating the role of intrinsic vs. extrinsic traits in extinction risk. Moreover, findings may contribute to preventing declines in other endangered and endemic taxonomic groups.