Meeting Abstract
Marine habitats vary widely in structure, from incredibly complex coral reefs through to less complex deep water and open ocean habitats. Hydromechanical models suggest that optimal morphologies differ between these habitats. Simple habitats are predicted to select for sustained efficient swimming, which can be achieved by fusiform body shapes. In contrast, complex habitats are predicted to select for maneuverability, which can be achieved by deep-bodied and laterally compressed forms. To look for a signature of these processes at a broad macroevolutionary scale, we tested for differences in body shapes between fishes living in complex and more simple habitats. We quantified body shapes across 3658 species of ray-finned fishes using a series of linear measurements informative to swimming kinematics. We scored each species for whether they lived in reefs, the most complex marine habitat, or not and tested for morphological differences in a phylogenetic framework. Our results confirmed significant overall shape differences between fishes living in complex and less complex marine habitats. Consistent with our predictions, reef species have on average deeper bodies, lower fineness ratios and higher depth/width ratios, while non-reef species are more streamlined with more tapering tails. Despite the numerous evolutionary forces that may influence body shapes at such a broad macroevolutionary scale, our results support the expected morphological differences predicted from hydromechanical models of swimming kinematics.
