Meeting Abstract

97.5  Thursday, Jan. 7  Phylogenetic Placement of Myxozoa: An exploration of conflict between phylogenomic and rDNA molecular data EVANS, N.M.**; CARTWRIGHT, P.; University of Kansas; University of Kansas evansnat@ufl.edu

Myxozoa is a diverse clade of microscopic obligate endoparasites, several of which can cause serious disease in a number of economically important fish. Yet despite this significance, myxozoan higher-level classification has proven difficult due to an overall paucity of morphological characters and, more recently, the discovery of this clade’s highly divergent molecular sequences. Currently there exists two competing molecular hypotheses for the placement of Myxozoa. The most recently advanced is based on a phylogenomic approach, which places the long branched myxozoan Buddenbrockia, with Cnidaria. The second hypothesis, based on a larger taxon sampling, but with a single marker, 18S rDNA, supports the placement of Myxozoa as a long-branched clade sister to Bilateria. As part of the Cnidarian Tree of Life Project, we investigated the phylogenetic placement of Myxozoa, evaluating the conflict and support for both hypotheses within and between traditional and phylogenomic datasets. Our efforts include augmentation of traditional 18S data with new 28S rDNA sequences and comprehensive taxon sampling of metazoans, including myxozoans and cnidarians. Effects of missing data as well as alternative amino acid substitution models are explored for the phylogenomic data. Our results suggest caution when interpreting results of long branched taxa due to the vulnerabilities inherent to both traditional and phylogenomic molecular approaches.