The Ecological Correlates of Mammal Coloration

Abstract

Mammals are relatively understudied in terms of their coloration, owing to their
predominately drab grey and brown colours when compared to other groups such as birds, amphibians, and insects. With most mammals being small, undefended prey such as rodents or bats, there is a strong selective pressure for cryptic coloration in this group. What research has been done on mammals has focused on the efficacy of such camouflage. Very little research attention has been given to other potential functions of mammalian colours and patterns. Using phylogenetic comparative methods on a global sample of terrestrial, non-volant mammal species, this study finds very little evidence for conspicuous patches of mammalian pelage being used as social signals, though white coloration might be important for signalling in nocturnal species, conspicuous rump patches might act as sexually-selected signals in some groups of mammal, and conspicuous pelage on distal body regions could be used in species identification for species in small social groups. When analysed in a Bayesian phylogenetic framework, mammals appear to follow one aspect of Gloger’s rule; species inhabiting warmer, more humid environments sport darker coloration, but not to follow the converse aspect; that species living in hotter, more arid environments sport redder coloration. There is also little evidence to suggest that Alfred Russell Wallace’s historical theories about animal colours in the tropics hold true when applied to mammals. With a variety of equipment and methodologies available to research animal coloration, it is vital that each method is validated to justify future research uses. When comparing a qualitative colour chart of mammalian pelage coloration to two quantitative measures; extracted amounts of pigmentation from hair samples and RGB colour values from photography, the colour chart was discovered to return values correlated with both methods, ensuring its validity for future use in mammal coloration research.

Date of Award	23 Jan 2024
Original language	English
Awarding Institution	University of Bristol
Supervisor	Tim Caro (Supervisor) & Davide Pisani (Supervisor)