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Developmental Plasticity and the Origin of Tetrapods
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Polypterus: Developmental Plasticity and the Origin of Tetrapods • Polypterus senegalus walking on a smooth surface. When raised on land, a primitive, air-breathing fish walks much better than its water-raised comrades, according to a new study. The landlubbers even undergo skeletal changes that improve their locomotion. The work may provide clues to how the first swimmers adapted to terrestrial life (Credit: Antoine Morin - Video 1 of 10.1038/nature13743). • Fish raised on land give clues to how early animals left the seas • http://news.sciencemag.org/biology/20... • Polypterus: Developmental Plasticity and the Origin of Tetrapods • http://www.standenlab.com/research/pr... • References • 1. Evolutionary developmental biology: Dynasty of the plastic fish • Nature (2014) doi:10.1038/nature13743 • http://www.nature.com/nature/journal/... • Ambitious experimental and morphological studies of a modern fish show how developmental flexibility may have helped early 'fishapods' to make the transition from finned aquatic animals to tetrapods that walk on land. • 2. Developmental plasticity and the origin of tetrapods • Nature (2014) doi:10.1038/nature13708 • http://www.nature.com/nature/journal/... • 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.
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