Clade-wide variation in bite-force performance is determined primarily by size, not ecology.

Justin E. Isip,Natalie Cooper,Marc E. H. Jones

doi:10.1098/rspb.2021.2493

Abstract

Performance traits are tightly linked to the fitness of organisms. However, because studies of variation in performance traits generally focus on just one or several closely related species, we are unable to draw broader conclusions about how and why these traits vary across clades. One important performance trait related to many aspects of an animal's life history is bite-force. Here, we use a clade-wide phylogenetic comparative approach to investigate relationships between size, head dimensions and bite-force among lizards and tuatara (lepidosaurs), using the largest bite-force dataset collated to date for any taxonomic group. We test four predictions: that bite-force will be greater in larger species, and for a given body size, bite-force will be greatest in species with acrodont tooth attachment, herbivorous diets, and non-burrowing habits. We show that bite-force is strongly related to body and head size across lepidosaurs and, as predicted, larger species have the greatest bite-forces. Contrary to our other predictions, tooth attachment, diet and habit have little predictive power when accounting for size. Herbivores bite more forcefully simply because they are larger. Our results also highlight priorities for future sampling to further enhance our understanding of broader evolutionary patterns.

Highlights

Performance traits are of vital importance for activities that influence organism survival, such as food acquisition, predator avoidance and mate acquisition [1,2,3,4]
We explored the distribution of raw bite-force across clades and families, and within tooth attachment, diet and substrate categories, and visualized the differences in bite-force and the four size measures in the full dataset, and the data for females and males separately
Bite-force was strongly positively correlated with snout–vent length (SVL) and head dimensions across the 161 species in our analyses

Summary

Introduction

Performance traits are of vital importance for activities that influence organism survival, such as food acquisition, predator avoidance and mate acquisition [1,2,3,4]. We explored the distribution of raw bite-force (i.e. biteforce values before correcting for size differences) across clades and families, and within tooth attachment, diet and substrate categories, and visualized the differences in bite-force and the four size measures in the full dataset, and the data for females and males separately.

Results

Conclusion