Meeting Abstract

28.8  Jan. 5  Paraphyly across oceans: a molecular phylogeny of the family Chromodorididae (Gastropoda: Nudibranchia) using three molecular markers TURNER, L.M.; WILSON, N.G.*; British Antarctic Survey, Cambridge; Scripps Insitute of Oceanography, University of California, San Diego wilsong@auburn.edu

The Chromodorididae are a colourful, speciose family of nudibranchs (sea slugs), and are found in all of the five oceans on earth. Like many marine invertebrate groups, their greatest diversity occurs in the tropical Indo-west Pacific. There are seventeen known genera, but only six of these are found in multiple biogeographic provinces; the rest are restricted to a single province. The monophyly of the family, and its constituent genera has not been examined to date, and provides an interesting test of molecular concordance with traditionally recognized marine biogeographic provinces. There are also several genera that are monotypic, which cannot be linked easily with other genera. The lack of well-supported phylogenetic hypotheses means that existing evidence showing coloration patterns within a genus were the result of shared ancestry, rather than mimicry, could not be tested across genera. We used three genes with differing rates of evolution (18S, 16S and COI) to try to answer the questions outlined above. Is the family monophyletic? Are the genera monophyletic, (especially those that occur in multiple biogeographic regions)? Can we link monotypic genera to other groups? Is mimicry occurring? We used Maximum Parsimony and Bayesian analyses to generate phylogenetic hypotheses for this family of sea slugs. We discovered that the family was monophyletic after the exclusion of one genus. However, most of the genera that encompass more than one biogeographic province were paraphyletic (Chromodoris, Hypselodoris, Glossodoris, Mexichromis). The current classification for these nudibranchs does not reflect evolutionary relationships, and requires revision.