Global latitudinal and bathymetric gradients in body size among cartilaginous fishes (Gnathostomata: Chondrichthyes)

This is a Preprint and has not been peer reviewed. This is version 1 of this Preprint. You must log in to post a comment. There are no comments or no comments have been made public for this article. This is a Preprint and has not been peer reviewed. This is version 1 of this Preprint. Add a Comment You must log in to post a comment. Comments There are no comments or no comments have been made public for this article. Understanding the macroecological rules governing body size variation across environmental gradients has long been a central focus of biology for centuries. Bergmann’s rule – the tendency for animals to reach larger body sizes in colder environments – has been studied in endotherms but with mixed support. However, phylogenetically informed tests of this rule in ectotherms remain scarce, and there is very limited evidence at higher taxonomic scales. Here, we provide robust evidence for Bergmann’s rule in Chondrichthyes (sharks, rays, and chimaera), a predominantly ectothermic clade, using a phylogenetically informed dataset of over 900 species extracted from existing databases and primary literature. We show that chondrichthyans tend to mature at larger sizes and also reach larger maximum body sizes at higher latitudes and in deeper habitats – a pattern that is consistent with Bergmann’s rule. We suggest that increased survivorship in these environments may promote evolutionary shifts toward greater resource allocation to growth and larger body sizes. This work fills a critical gap in testing Bergmann’s rule among ectotherms in a phylogenetic context, demonstrating the potential for environmental gradients to shape the evolution of body size in marine vertebrates. https://doi.org/10.32942/X24X05 Ecology and Evolutionary Biology, Evolution, Life Sciences, Other Ecology and Evolutionary Biology, Terrestrial and Aquatic Ecology Life history, Sharks, Temperature-size rule, Bergmann's rule, Ectotherm, Evolution Published: 2026-03-11 17:32 CC BY Attribution 4.0 International Conflict of interest statement: None Data and Code Availability Statement: Data, code, and supplementary materials will be made fully available in an open-access repository upon acceptance. Language: English