Convergence in the Shape of Frog Toepads

Abstract

Convergent evolution is the process in which unrelated species have independently evolved to have similar traits as each other despite not having a recent common ancestor.  For example, species of anurans are highly diverse, yet there are great resemblances in the structure of toepads amongst unrelated frogs.  Many studies have focused on the size of the toepads and adhesion.  However, none have studied the actual shape of the toepads.  We studied a total of 624 individual museum specimens from 167 different species.  We took pictures of the toepads of every specimen and made an outline of the shape.  Our analyses showed convergence in the shape of toepads because most species had the same relative shape despite being from different microhabitats.  However, there were unique shapes that diverged from the typical shape.  The species that had these unique shapes weren’t closely related, and therefore independently evolved the unique shapes.