Evolution of avian foot morphology through anatomical network analysis

Abstract

The avian evolutionary pathway led to morphological adaptive variations in their15 feet. Diverse foot types are accompanied by a complex muscle system, allowing16 birds to adopt different primary lifestyles, and to display various locomotor and17 manipulative skills. We provide novel insights of evolutionary and functional18 significance on the avian foot architecture through Anatomical Network Analysis.19 Here we show that there is no link between the more complex foot networks and20 the ability to perform more specialized skills or a higher number of different tasks.21 Additionally, there is a trend towards the simplification of foot networks on a22 microevolutionary scale. The anatomical parts largely conserved in living birds23 and already present in ancestral dinosaurs exhibit the highest connectivity degree,24 a network parameter related to the constraint of an anatomical part for25 evolutionary change. Foot networks are phylogenetically constrained and26 conserved in all birds despite their foot type diversity. We suggest that this27 scenario could be the result of stabilizing selection, which led the connectivity of28 anatomical parts of the foot to be conserved.