DISSERTATION RESEARCH: Evolution of Asymmetry in Flatfishes (Pleuronectiformes: Percomorpha)

American Museum Natural History, New York NY

Investigators

Abstract

Flatfishes (Pleuronectiformes), the commercially important soles, flounders, and halibuts, exhibit one of the most remarkable vertebrate metamorphoses, where one eye of a bilaterally (left-right) symmetrical larva migrates to the opposite side of the head, resulting in highly asymmetrical juvenile and adult forms. Despite the complexity and uniqueness of this transformation, virtually nothing is known about its evolutionary origin or the mechanism behind the change. Flatfishes are the only vertebrates to deviate so dramatically from a bilaterally symmetrical body plan, making them an ideal group to conduct the first comparative studies of regulatory genes and anatomical structures associated with this body asymmetry. Through analyses of DNA sequence data and MRI images we aim to resolve the evolutionary relationships of flatfishes, examine the evolution of developmental regulatory genes involved in left-right axis formation and assess the origins of structures in the head hypothesized to be unique to flatfishes and to have evolved as adaptations to a life on the sea floor. Examination of anatomical structures associated with vertebrate asymmetry and of the molecular mechanisms generating this bizarre anatomy will provide for a novel interpretation of the evolution of bilateral asymmetry.