3D geometric morphometric analysis of phenotypic plasticity in the pectoral girdle of a basal actinopterygiian fish

Abstract

Polypterids are a basal group of actinopterygian fishes that represent a possible living analogue for the evolutionary transition from fish to tetrapods for number of reasons, including their ability to walk on land using robustly, muscled pectoral fins. We examined the phenotypic plasticity in the pectoral anatomy of Polypterus senegalus induced by habitual terrestrial locomotion. Fish were reared in a fully terrestrial environment where they were forced to live and locomote over land for up to two years. MicroCT scans were taken of the experimental walking group and a swimming control group. 3D reconstructions of the pectoral anatomy were described using spherical harmonics, a 3D extension of elliptic Fourier analysis. Here we present a geometric morphometric analysis of morphological differences in the pectoral anatomy between swimming and walking fish, and discuss potential small‐scale morphological changes in response to the functional demands of terrestrial locomotion during the fin‐to‐limb transition.Grant Funding Source: NSERC, Canada Research Chair, Tomlinson Postdoctoral Fellowship