DOCTORAL DISSERTATION: Evolution of neural circuits underlying species-specific swimming behaviors in opisthobranch molluscs

Georgia State University Research Foundation, Inc., Atlanta GA

Investigators

Abstract

Understanding the neural mechanisms that cause species to behave differently has been an elusive goal in biology. This project, which is part of a doctoral dissertation, uses the nervous systems of sea slugs (opithobranch molluscs) to address this issue by comparing neural circuits underlying swimming behavior. Sea slugs have large neurons and simple nervous systems, allowing researchers to map out neural circuitry underlying equally simple behaviors. Some sea slug species swim by flexing their bodies up and down. Other species either do not swim or swim by other means. The neural circuitry underlying up and down swimming has been determined in two species: Tritonia diomedea and Pleurobranchaea californica. The neural circuits and interactions underlying swimming in these two species are remarkably similar even though these animals are not closely related. There is evidence to suggest the ability to swim evolved independently using the same (or homologous) neurons. This leads to the prediction that other species that swim in this manner would also use the same neurons and neural interactions to produce the behavior. To test this intriguing prediction, a third species of sea slug that swims with up and down movements will be be studied. The only readily available species are found in Australia. Electrophysiological, pharmacological, and histological approaches will be employed by the student to study the Australian species to determine if it also uses the same neurons and neural mechanisms. The results of this project will contribute to our understanding of the neural mechanisms that allowed behavior to evolve. A positive result would show that behavior could predict neural circuitry in animals that independently evolved the behavior. A negative result would still be interesting because it would show that similar behaviors can be produced by different mechanisms. There are several broader impacts of this project. The first is that it will be a training opportunity for the student that will greatly enhance his dissertation project. The work will also establish a new partnership with colleagues internationally. The results of this project will be disseminated broadly both in the form of research papers, but also as contributions to NeuronBank.org, a project that tracks identified neurons and synaptic connections.