Tom Titus
titus@darkwing.uoregon.edu

University of Oregon
Institute of Neuroscience
1254 University of Oregon
Eugene, OR 97403-1254 USA

Advisors:
Dr. John H. Postlethwait, Institute of Neuroscience

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Research Interests

Previously my research focused on developing molecular phylogenetic trees for various groups of salamanders and lizards at a variety of taxonomic levels. These trees provided the historical framework for testing evolutionary hypotheses regarding variation in life histories (Titus and Larson, 1995), morphology (Titus and Larson, 1996; Vitt et al., 1997, Frost et al., 2001), and for evaluating procedures used in DNA sequence alignment (Titus and Frost, 1996; Frost et al., 2001).

 My current research focuses on the nature of genome evolution following duplication using the zebrafish (Danio rerio) as a model system. Zebrafish linkage groups 3 and 12 share many closely related gene pairs indicating they are the result of a genome wide duplication event early in the history of teleost fishes. A zebrafish PAC library is screened for clones containing these duplicate gene pairs and the entire insert is is subjected to random subcloning and shotgun sequencing. The resulting data represent an extremely fine-grained physical map of small (100kb) duplicated regions that provide a means for addressing the following questions: 1) How has genomic organization of individual genes evolved following duplication? 2) How has gene content and gene order of smaller regions changed following duplication and how does this compare with similar changes on a larger scale? 3) Can changes in duplicated regulatory regions be identified that correlate with changes in timing and/or tissue specificity of gene expression?

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Publications

• Frost, D.R., R. Etheridge, D. Janies, and T.A. Titus. 2001. Total evidence, sequence alignment, the evolution of the polychrotid Lizards, and a reclassification of the Iguania (Squamata: Iguania). American Museum Novitates, in press. 
• Frost, D.R., H.M. Crafts, L. Fitzgerald, and T.A. Titus. 1998. Geographic variation, species recognition, and molecular evolution of cytochrome oxidase I in the Tropidurus spinulosus complex (Iguania: Tropiduridae). Copeia 1998:839-851. 
• Vitt, L.J., J.P. Caldwell, P.A. Zani, and T.A. Titus. 1997. The role of habitat shift in the evolution of lizard morphology: Evidence from tropical Tropidurus. Proc. Natl. Acad. Sci. USA 94:3828-3832.
• Titus, T.A. and A. Larson. 1996. Molecular phylogenetics of desmognathine salamanders (Caudata: Plethodontidae): A reevaluation of evolution in ecology, life history, and morphology. Syst. Biol. 45:451-472.
• Titus, T.A. and D.R. Frost. 1996. Molecular homology assessment and phylogeny in the lizard family Opluridae (Squamata: Iguania). Mol. Phylo. Evol. 6:49-62. 
• Titus, T.A., E.O. Wiley, and M. Allen. 1996. Allozyme variation in the longnose shiner, Hypopsis longirostris (Cyprinidae: Teleostei). Bull. Alabama Mus. Nat. Hist. 
• Shaw, K., E.O. Wiley, and T.A. Titus. 1995. Phylogenetic relationships among members of the Hypopsis amblops species group. Occas Pap. Mus. Nat. Hist. Univ. Kansas. 172:1-28. 
• Titus, T.A. and A. Larson. 1995. A molecular phylogenetic perspective on the evolutionary radiation of the salamander family Salamandridae. Syst. Biol. 44:125-141. 
• Titus, T.A. 1994. Tissue-specific gene expression in the small mouth salamander, Ambystoma texanum (Caudata: Ambystomatidae). Biochem. Syst. Ecol. 22:477-489. 
• Wiley, E.O. and T.A. Titus. 1992. Phylogenetic relationships among members of the Hypobsis dorsalis species group (Teleostei: Cyprinidae). Occas Pap. Mus. Nat. Hist. Univ. Kansas. 
• Titus, T.A. and M.S. Gaines. 1991. Genetic variation in lowland and montane populations of Ambystoma gracile (Caudata: Ambystomatidae). Occas. Pap. Mus. Nat. Hist. Univ. Kansas. 141:1-12. 
• Wiens, J.J. and T.A. Titus. 1991. Phylogenetic relationships of Spea (Anura: Pelobatidae). Herpetologica 47:21-28. 
• Titus, T.A. 1990. Genetic variation in two subspecies of Ambystoma gracile Baird (Caudata: Ambystomatidae). Journal of Herpetology 24:107-111. 
• Titus, T.A. 1991. Use of road-killed amphibians in allozyme electrophoresis. Herp. Review 22:14-16. 
• Titus, T.A., D.M. Hillis, and W.E. Duellman. 1989. Color pattern polymorphism in neotropical treefrogs: an allozymic investigation of the taxonomic status of Hyla favosa (Cope). Herpetologica 45:17-23.