GELLER, J.B.: Evolution of clonality and symbiosis in sea anemones (Anthopleura): phylogenetic and functional genomic approaches.

Clonality and symbiosis, widespread traits among marine invertebrates, are usually evolutionarily conserved in genera of marine invertebrates. Sea anemones in the genus Anthopleura, however, contain members with that lack one or both of these traits. Anthopleura is thus an attractive model to explore adaptive and functional aspects of these ecologically important traits. A phylogeny based on two mitochondrial genes for 13 species of Anthopleura reveals multiple gains and losses of these traits in at least three resolved clades. Symbiosis appears to have been gained independently in western and eastern Pacific species. Mitochondrial DNA evolution has proven to evolve quite slowly in Anthozoa. Therefore, we have sequenced nuclear introns in the genes for arginine kinase and a G-protein coupled receptor to better resolve branching order in the eastern Pacific group of species. To investigate the evolution of clonality and symbiosis from a functional perspective, we have cloned and isolated over 600 cDNAs from A. elegantissima, of which 347 have significant similarity to known genes. Of these, several may be inferred to play a role in fission. These are genes involved in the degradation of extracellular matrix (mesoglea) and involved in apoptosis. Future work will investigate patterns of the expression of these genes and the construction of high density cDNA arrays for genome-wide probing of gene activity in fission and symbiosis.