Eye size and investment in frogs and toads correlate with adult habitat, activity pattern and breeding ecology

Frogs and toads (Amphibia: Anura) display diverse ecologies and
behaviours, which are often correlated with visual capacity in other
vertebrates. Additionally, anurans exhibit a broad range of relative eye
sizes, which have not previously been linked to ecological factors in this
group. We measured relative investment in eye size and corneal size for
220 species of anurans representing all 55 currently recognized families
and tested whether they were correlated with six natural history traits
hypothesized to be associated with the evolution of eye size. Anuran eye
size was significantly correlated with habitat, with notable decreases in
eye investment among fossorial, subfossorial and aquatic species. Relative
eye size was also associated with mating habitat and activity pattern.
Compared to other vertebrates, anurans have relatively large eyes for
their body size, indicating that vision is probably of high importance.
Our study reveals the role that ecology and behaviour may have played in
the evolution of anuran visual systems and highlights the usefulness of
museum specimens, and importance of broad taxonomic sampling, for
interpreting macroecological patterns.