Meeting Abstract

P3.204  Tuesday, Jan. 6  Determining an optimal sequence divergence for phylogenetic analyses COX, Christian L. *; MAKOWSKY, Robert; ROELKE, Corey E.; University of Texas at Arlington; University of Texas at Arlington; University of Texas at Arlington clcox@uta.edu

Determining the appropriate gene for phylogeny reconstruction can be a difficult process. Rapidly evolving genes tend to resolve recent relationships, but suffer from alignment issues and increased homoplasy between distantly related species. Conversely, slowly evolving genes work well for deeper relationships, but lack sufficient variation to resolve recent relationships. We attempt to determine the optimal level of sequence divergence for resolving phylogenetic relationships at different levels using a known phylogeny. We compiled the known phylogeny using well-supported relationships between 28 taxa within the phylum Chordata. Sequences of 7 mitochondrial protein coding genes, 1 mitochondrial ribosomal gene, 2 nuclear protein coding genes and 2 nuclear ribosomal genes were acquired for each taxa, and Bayesian posterior probabilities for the correct nodes were calculated for each gene. Across all genes, we found that 15-25% sequence divergence was optimal for resolving the correct relationships. However, the ability of a gene to resolve the correct relationship varied among gene type, with protein coding genes correctly resolving relationships at very low divergence (less than 15%), while ribosomal genes correctly resolved at greater sequence divergence (20%). This information should be useful for selecting the right gene to clarify intractable relationships, as well as minimizing both cost and confounding information during project design.