Meeting Abstract
S8.11 Wednesday, Jan. 6 Investigating cnidarian phylogeny using rDNA secondary structure models CARTWRIGHT, Paulyn*; BARBEITOS, Marcos S.; COLLINS, Allen G.; DALY, Marymegan; FRANCE, Scott C.; MCFADDEN, Catherine S.; University of Kansas; University of Kansas; National Systematics Lab of NOAA’s Fisheries Service; Ohio State University; University of Louisiana at Lafayette; Harvey Mudd College pcart@ku.edu
Elucidating higher-level cnidarian relationships presents challenges due to the ancient and rapid divergences between many of the major cnidarian lineages. Cnidaria contains a deep divergence separating two major clades, Anthozoa and Medusozoa. The monophyly of these two clades is well supported by compelling morphological and molecular evidence. However, there is uncertainty about many of the major relationships within each of these clades. As part of the Cnidarian Tree of Life effort, we sequenced nearly complete large and small subunit nuclear ribosomal (18S and 28S) and partial large subunit mitochondrial (16S) genes in a comprehensive sampling of cnidarian taxa. Ribosomal genes have traditionally been useful in elucidating higher-level relationships, but alignment is problematic due to length variable regions within these molecules. These length variable regions are often removed from phylogenetic analyses, which can reduce the number of potentially informative characters. In an effort to improve the alignment and maximize the number of unambiguously aligned characters, we incorporated models of secondary structure into our alignment. These models were developed specifically for cnidarians and enable us to confidently increase the number of hypothesized homologous regions in the rDNA molecules and thus retain more potentially informative sites. Here we present the results of our analyses and evaluate the utility of secondary structure models for investigating cnidarian phylogeny. In addition, we present the most up to date phylogenetic framework for Cnidaria and discuss these patterns and their implications for early cnidarian evolution.
