Meeting Abstract

P3.191  Sunday, Jan. 6  The diversity and evolution of locomotor muscle properties in anurans ASTLEY, H. C.*; ROBERTS, T. J.; Brown University henry_astley@brown.edu

Anuran jumping is a model system for linking muscle physiology to organismal performance. However, anuran species display substantial diversity in their locomotion and morphology, reflecting their habitats (including aquatic, terrestrial, arboreal, and fossorial environments) as well as other factors (such as protective toxins). Some anurans are renowned for performing powerful leaps from riverbanks or tree branches, but other species move predominantly via burrowing, swimming, short hops, or even diagonal-sequence gaits. Many anurans with similar locomotion and morphology are actually convergent, with “tree frogs” and “walking frogs/toads” both evolving independently several times. On the other hand, closely related species may differ drastically, as with the bullfrog-like Bufo asper compared to other, more typical Bufonid toads. These multiple convergences and divergences allow us to examine the extent to which phylogeny constrains multiple muscle properties linked to locomotor performance, as well as the interdependence of these muscle properties. We hypothesized that traits which must be altered by changes to the muscle proteins (such as maximal shortening speed) would be strongly constrained by ancestry, while traits which can also be altered by changes in expression level (such as relaxation time) would show less constraint. We performed locomotor tests (jumping or running) on 32 total individuals of eight species of anurans, followed by in vitro tests on the semimembranosus and plantaris longus muscles. Preliminary results show significant variation in muscle properties across species, and the ongoing addition of more species to the dataset will allow explicit statistical testing of phylogenetic and functional influences on muscle properties.