Abstract

A species' vulnerability to extinction is influenced by both extrinsic threats (e.g., habitat loss and invasive species) and intrinsic biological traits (such as life-history traits, reproductive mode, and reproductive output). In this study, we investigated the roles of intrinsic biological traits in determining the risk of extinction across 960 oviparous species of non-avian reptiles. Our findings revealed that vulnerability to extinction is negatively correlated with clutch size, but positively correlated with egg size when controlling for body size. Surprisingly, we found that body size alone is not a predictor of extinction risk. Additionally, we observed a nonsignificant relationship between the activity phase and vulnerability to extinction across oviparous species. These results suggest that the increased risk of endangerment in oviparous reptiles may stem from declining population density due to decreasing clutch size and increasing egg mass.