Standen et al, 2014 wrote: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.

My research program has three central objectives.

First, to understand the developmental flexibility of vertebrates over ontological time scales. Environmental conditions change and animals are forced to change with them. My research focuses on how environmental conditions throughout ontogeny can affect an animal’s functional morphology and behaviour. Biomechanical metrics help quantify to what degree a species is able to adapt behaviourally to environmental changes. Understanding the developmental flexibility of animals to their environments may clarify some of the epigenetic influences on adaptation and evolution.

"I'm very surprised the fish survived so well on land," said Standen, who conducted this research while she was a postdoctoral researcher at McGill University in Montreal.