MCHUGH, Damhnait; Colgate University, Hamilton NY: Phylogenetic Analyses of Annelid Relationships Using Nuclear Coding Genes

Developing a robust hypothesis of annelid relationships will inform us about the evolution of segmentation, whether the ancestral annelid was a burrowing form or a surface-dwelling crawler, and the identity of the closest living relative to the clitellates. It will also shed light on the phylogenetic position of enigmatic groups such as the semi-terrestrial polychaetes, the interstitial annelids, and the planktonic forms. A comprehensive phylogenetic analysis of all annelid groups using DNA sequences from four nuclear coding genes for over 100 species is underway. The genes are elongation factor-1&alpha (1200 bp), elongation factor-2 (1400 bp), RNA polymerase II (700 bp), and myosin heavy chain type II (700 bp). Results from separate and combined parsimony and maximum likelihood analyses of these data sets for up to 50 taxa show that while some sister group relationships are well supported (e.g., Onuphidae and Eunicidae, Maldanidae and Arenicolidae), basal relationships are not. These results from multiple independent data sets indicate a rapid early radiation of the group. The addition of taxa, the combination of these data with genomic-level data (e.g., mitochondrial gene order), and specific hypothesis-testing are underway to determine whether robust resolution of basal nodes is possible. Funded by the National Science Foundation (U.S.A) (EAR 0342392)