Effects of evolutionary history and life form on extinction risk of Chinese flowering plants

There has been much debate on what, including evolutionary history, ecological processes or environmental change, might contribute to species extinctions. In this study, we explored how evolutionary attributes and life forms were correlated with extinction risk of Chinese flowering plants. We defined genus-level extinction risk as the ratio of threatened species over all species in each plant genus. We compiled data on extinction risk for 2731 genera representing 27332 angiosperm species from the IUCN Red List threatened species assessments. We quantified the strength of phylogenetic signal in extinction risk and used phylogenetic generalized linear mixed models to test the effects of evolutionary age, genus size, and evolutionary distinctiveness on extinction risk. We found woody plants suffered greater extinction risk than herbs. There were significant phylogenetic signals in extinction risk, but the signal was stronger in herbaceous plants than in woody plants. Genus size and genus stem age were both negatively associated with extinction risk. In constrast, we found positive correlations between evolutionary distinctiveness and extinction risk. We further indentified many genera (e.g., Cynomorium, Mytilaria, Kingdonia, Scheuchzeria, Brasenia, and Manglietia) had both high evolutionary distinctiveness and high extinction risk. Our study shows that the extinction risk of Chinese flowering plant is not randomly distributed across genera but has strong evolutionary predisposition. We suggest information on life forms, genus size, genus stem age, and evolutionary distinctiveness be considered when making priority for the protection of Chinese flowering plants.