Body Size in Ray-Finned Fishes

Abstract

Bergmann’s rule predicts a change in body size with latitude, with larger members of a taxonomic group occurring further from the equator. This pattern has been described for many groups of organisms; however, no study has assessed this relationship across a substantial number of ray-finned fish species, the largest group of vertebrates. I performed Bayesian phylogenetic modeling using maximum length and latitude data for 3021 species of actinopterygians to assess Bergmann’s rule in the group. The impact of salinity tolerance on the relationship between length and latitude was also considered. Maximum length and salinity tolerance data were obtained from FishBase, and latitude data were obtained from museum records. I found that, overall, Bergmann’s rule holds and is not significantly affected by salinity tolerance except when not considering phylogeny, in which case only marine species show the trend.