Genomic Organization and Evolution of Cephalopod Brains

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The origin of nervous systems with complex brains represents a major evolutionary transition in the history of animals. Investigators will test alternative hypotheses for brain/memory evolution to determine whether these functions have single or multiple origins. Genes expressed in Octopus brains will be studied and compared with genes expressed in the brains of other mollusks. New ways of assessing evolutionary relationships between the genes from the different animals will be developed in order to determine whether different animal groups use the same genes during brain development or whether each type of animal has a different set of genes that organize brain centers during development. Project outcomes include making available to the wider research community inexpensive gene analysis techniques with short processing turn-around times. The project will provide opportunities for students to combine research training with field-based marine biodiversity research in Puerto Rico, American Samoa, Palau, and Hawaii. Outreach activities are planned for K-12 teachers and students. This project will investigate whether brains from diverse phylogenetic groups originate from a single ancestral cell lineage or whether neurons and the brains they form have developed from different lineages representing multiple, perhaps 9-12, cephalization events. The tripartite brain hypothesis predicts that the bilaterian brain is composed of three distinct regions which are determined by a set of conserved transcription factors, Hox, Otx, and Pax2/5/6, whereas an alternate view is that cephalopod-specific innovations may have led to independent formation of the complex brains of species in this group. Single-neuron genomics and connectivity will be used to reconstruct the evolutionary fate of homologous cell populations in cephalopod and chordate brains.