|
Bedford Web site
Fields of study
Population genetics
Mentor
Mercedes Pascual
Research interests
I'm broadly interested in the process of adaptation. I did my thesis work on the "molecular clock,” looking at the tempo of protein evolution in yeast, Drosophila and mammals. I found that the pattern of protein evolution is significantly more random than the Poisson expectation, meaning that protein substitutions tend to cluster on a phylogeny. Correlations between time, rate of substitution and population size suggest that the extra randomness observed can be explained with reference to "nearly-neutral networks" of amino acid substitutions. In this framework, when a substitution occurs it influences the effects that future mutations have on the protein. This results in a change in the rate of evolution with every substitution event. I hypothesize that these hidden fluctuations are what cause the observed deviation from a "molecular clock.”
Currently, I am investigating similar themes in the evolution of the influenza virus. The rich genomic and epidemiological record makes influenza particular amenable to such analysis.
Select publications
Bedford, T., S. Cobey, P. Beerli, and M. Pascual. Global migrational dynamics underlie evolution and persistence of human influenza A (H3N2). Submitted.
Bedford, T., and D. L. Hartl. 2009. Optimization of gene expression by natural selection. Proc. Natl. Acad. Sci. USA 106: 1133-1138.
Rogers, R. L., T. Bedford, and D. L. Hartl. 2009. Formation and longevity of chimeric and duplicate genes in Drosophila melanogaster. Genetics 181: 313-322.
Bedford, T. and D. L. Hartl. 2008. Overdispersion of the molecular clock: temporal variation of gene-specific substitution rates in Drosophila. Mol. Biol. Evol. 25:1631-1638.
Bedford, T., I. Wapinski and D. L. Hartl. 2008. Overdispersion of the molecular clock varies between yeast, Drosophila and mammals. Genetics 179:977-984.
Volkman, S. K., E. Lozovsky, A. E. Barry, T. Bedford, L. Bethke, A. Myrick, K. P. Day, D. L. Hartl, D. F. Wirth and S. A. Sawyer. 2007. Genomic heterogeneity in the density of noncoding single-nucleotide and microsatellite polymorphisms in Plasmodium falciparum. Gene 387(1-2):1-6.
Castillo-Davis, C.I., T. Bedford, and D.L. Hartl. 2004. Accelerated rates of intron gain/loss and protein evolution induplicate genes in human and mouse malaria parasites. Mol. Biol. Evol. 21:1422-1427.
Nielsen, K.M., J. Kasper, M. Choi, T. Bedford, K. Kristiansen, D.F. Wirth, S.K. Volkman, E.R. Lozovsky, and D.L. Hartl. 2003. Gene conversion as a source of nucleotide diversity in Plasmodium falciparum. Mol. Biol. Evol. 20:726-734.
Feder M.E., T. Bedford, D.R. Albright, and P. Michalak. 2002. Evolvability of Hsp70 expression under artificial selection for inducible thermotolerance in independent populations of Drosophila melanogaster. Phys. Biochem. Zool. 75(4):325-334.
|
|
|
