title: Developmental plasticity and the origin of tetrapods.
abstract: The origin of tetrapods from their fish antecedents, approximately 400 million years ago, was coupled with the origin of terrestrial locomotion and the evolution of supporting limbs. Polypterus is a member of the basal-most group of ray-finned fish (actinopterygians) and has many plesiomorphic morphologies that are comparable to elpistostegid fishes, which are stem tetrapods. Polypterus therefore serves as an extant analogue of stem tetrapods, allowing us to examine how developmental plasticity affects the 'terrestrialization' of fish. We measured the developmental plasticity of anatomical and biomechanical responses in Polypterus reared on land. Here we show the remarkable correspondence between the environmentally induced phenotypes of terrestrialized Polypterus and the ancient anatomical changes in stem tetrapods, and we provide insight into stem tetrapod behavioural evolution. Our results raise the possibility that environmentally induced developmental plasticity facilitated the origin of the terrestrial traits that led to tetrapods.
authors.affiliation: Biology Department, University of Ottawa, Gendron Hall, 30 Marie Curie Private, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: Emily M
authors.initials: EM
authors.lastname: Standen
authors.affiliation: Redpath Museum, McGill University, 859 Sherbrooke Street West, Montreal, Quebec H3A 0C4, Canada.
authors.forename: Trina Y
authors.initials: TY
authors.lastname: Du
authors.affiliation: Redpath Museum, McGill University, 859 Sherbrooke Street West, Montreal, Quebec H3A 0C4, Canada.
authors.forename: Hans C E
authors.initials: HC
authors.lastname: Larsson
mesh_terms: D058500:Animal Fins / Q000033:anatomy & histology / Q000502:physiology; D000818:Animals; D005075:Biological Evolution; D001696:Biomechanical Phenomena; D001842:Bone and Bones / Q000033:anatomy & histology / Q000502:physiology; D004777:Environment; D005121:Extremities / Q000033:anatomy & histology* / Q000254:growth & development*; D005260:Female; D005399:Fishes / Q000033:anatomy & histology* / Q000145:classification / Q000254:growth & development* / Q000502:physiology; D008124:Locomotion; D008297:Male; D023421:Models, Animal; D009132:Muscles / Q000033:anatomy & histology / Q000502:physiology; D010802:Phylogeny; D013550:Swimming / Q000502:physiology; D013997:Time Factors; D016138:Walking / Q000502:physiology