title: Does aquatic foraging impact head shape evolution in snakes?
abstract: Evolutionary trajectories are often biased by developmental and historical factors. However, environmental factors can also impose constraints on the evolutionary trajectories of organisms leading to convergence of morphology in similar ecological contexts. The physical properties of water impose strong constraints on aquatic feeding animals by generating pressure waves that can alert prey and potentially push them away from the mouth. These hydrodynamic constraints have resulted in the independent evolution of suction feeding in most groups of secondarily aquatic tetrapods. Despite the fact that snakes cannot use suction, they have invaded the aquatic milieu many times independently. Here, we test whether the aquatic environment has constrained head shape evolution in snakes and whether shape converges on that predicted by biomechanical models. To do so, we used three-dimensional geometric morphometrics and comparative, phylogenetically informed analyses on a large sample of aquatic snake species. Our results show that aquatic snakes partially conform to our predictions and have a narrower anterior part of the head and dorsally positioned eyes and nostrils. This morphology is observed, irrespective of the phylogenetic relationships among species, suggesting that the aquatic environment does indeed drive the evolution of head shape in snakes, thus biasing the evolutionary trajectory of this group of animals.
authors: UMR CNRS/MNHN 7179, Mécanismes Adaptatifs: des Organismes aux Communautés, 55 Rue Buffon, 75005 Paris, France Laboratoire de Physique et Mécanique des Milieux Hétérogènes (PMMH), UMR CNRS 7636; PSL-ESPCI, 10 Rue Vauquelin, 75005 Paris, France Sorbonne Paris Cité-UDD, Univ. Paris 07, Paris, France marion.segall@live.fr.
authors: Marion
authors: 0000-0002-4913-2106
authors: M
authors: Segall
authors: ISYEB UMR7205 CNRS, MNHN, UPMC, EPHE. 45 Rue Buffon, 75005 Paris, France.
authors: Raphaël
authors: R
authors: Cornette
authors: UMR CNRS/MNHN 7179, Mécanismes Adaptatifs: des Organismes aux Communautés, 55 Rue Buffon, 75005 Paris, France.
authors: Anne-Claire
authors: AC
authors: Fabre
authors: Laboratoire de Physique et Mécanique des Milieux Hétérogènes (PMMH), UMR CNRS 7636; PSL-ESPCI, 10 Rue Vauquelin, 75005 Paris, France.
authors: Ramiro
authors: R
authors: Godoy-Diana
authors: UMR CNRS/MNHN 7179, Mécanismes Adaptatifs: des Organismes aux Communautés, 55 Rue Buffon, 75005 Paris, France Evolutionary Morphology of Vertebrates, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium.
authors: Anthony
authors: A
authors: Herrel
mesh_terms: D000818:Animals; D001070:Appetitive Behavior; D059001:Aquatic Organisms; D005075:Biological Evolution; D006257:Head / Q000033:anatomy & histology*; D010802:Phylogeny; D012911:Snakes / Q000033:anatomy & histology* / Q000502:physiology
keywords: aquatic snakes; constraints; convergence; geometric morphometrics; head morphology; hydrodynamics