Sex biases and the scarcity of sex metadata in global herpetology collections

Natural history specimens are a widely used and valuable resource for conservation, ecology, and evolutionary biology. One might assume that these collections are representative of natural populations, but recent work has suggested that many collections have disproportionately more male than female specimens. Here, we investigate sex ratios in > 5 000 000 amphibian and reptile specimen records from global natural history collections. We found a slight bias towards males in amphibians (39% females) and reptiles (47% females), but this varied among orders and families. Body size, sexual size dimorphism, and year of collection had little effect. Strikingly however, > 95% of herpetology specimen records had no sex data associated with them at all, even from recent collections. This lack of sex data substantially limits the utility of herpetological museum collections in many ways. We propose that enhanced efforts to train taxonomic specialists and support their careers would unlock the potential of sex-based research using museum collections and their associated public databases.