Blair Hedges, Thesis Supervisor Dr. Stephen Blair Hedges, Thesis Supervisor Dr. Bernhard Lüscher, Thesis Honors Advisor Andrew George Stephenson, Faculty Reader
The diversification of nematode species has thus far not been timed in a large-scale analysis. In this study, 761 nematode species and 54 outgroup species are timed using molecular methods. Pre-aligned 18S rRNA sequences were obtained from the Silva database and their phylogeny was constructed using maximum likelihood. Nodes of the resulting tree were timed using a Bayesian method and with fossil calibrations. Nematodes appear to have split from other phyla, such as arthropods and chordates, approximately 1000 million years ago (MYA), which is corroborated by other molecular studies. The model organisms Caenorhabditis rhabditis and C. briggsae split 110 MYA. Although this study consists of a single-gene analysis, it paves the way for more in-depth research in the future on nematode lineage diversification.
