Meeting Abstract
A typical frog may elicit the image of a small, leggy vertebrate with bulging eyes. However, relative eye size is highly variable among different species of frogs and toads (Amphibia: Anura). Larger eyes are costlier, but can improve visual performance, so variation in eye size has direct functional implications for vision. Research into major vertebrate groups such as birds, mammals, reptiles, and fishes has shown that ecological traits such as habitat, activity pattern, and behaviours associated with vision are often correlated with the relative sizes of eyes across species. However, anuran eye size has been understudied despite a stunning diversity of anuran ecologies and behaviours, and a single published study found no correlations between eye size and ecology in anurans. We measured anuran eye, cornea, and body sizes in 642 adult specimens representing 211 species and all 55 currently recognized families, and scored five natural history traits for all species from available literature in order to test for ecological correlates of relative eye size. Our data showed that frogs have large relative eye sizes compared to other vertebrates, and their eye diameters scale isometrically with the cube root of mass across species. Relative eye sizes were correlated with adult habitat and breeding ecology. Our study demonstrates the salient role that ecology has played in the evolution of anuran visual systems and highlights the importance of broad taxonomic sampling for detecting macroevolutionary patterns of trait evolution.
