Meeting Abstract

56.3  Tuesday, Jan. 6  Molluscan phylogeny investigated using three nuclear protein-coding genes KOCOT, K. M.*; HALANYCH, K. M.; Auburn University; Auburn University kmkocot@auburn.edu

With over 130,000 described extant species, Mollusca is the second most diverse animal phylum. Surprisingly, the phylogenetic relationships among the eight major lineages of Mollusca remain largely unknown. Although relatively few molecular phylogenetic studies have addressed mollusk higher-level relationships, the results of these studies have called into question several long held hypotheses of molluscan phylogeny such as the Diasoma hypothesis, the monophyly and basal position of the aplacophorans, and even the monophyly of Bivalvia and Gastropoda. These studies which have relied mostly on 18S, 28S, and mitochondrial genes have been unable to resolve most higher-level molluscan relationships. Conserved nuclear protein-coding genes have been shown to be useful for higher-level metazoan phylogenetics but little work using such genes as molecular markers has been done on molluscs. Therefore, we have employed constitutively expressed nuclear protein-coding genes novel to deep mollusk relationships which can be relatively easily obtained from molluscs and other lophotrochozoans. Specifically, we have sequenced large fragments of heat shock protein 90A (Hsp90A), sodium/potassium ATPase alpha subunit (NaK), and elongation factor 1 alpha (EF-1a) for a total of ~6.6 kbp per taxon from a diverse set of molluscs. These highly conserved, single copy genes were carefully selected for use as molecular markers on the basis of analyses of available sequence data from GenBank, genomes and EST libraries. These preliminary phylogenetic analyses indicate that these genes have good potential to provide insight into mollusc higher-level phylogeny. This approach allows us to collect a complete set of data for a large number of taxa relative to phylogenomic (EST-based) investigations at a much lower cost.