Ronald W. DeBry

I work at the intersection of phylogenetics, evolutionary biology, and molecular biology. I use DNA sequences (primarily from nuclear protein-coding genes) to infer phylogenetic relationships. I also use phylogenies to help discover how gene sequences evolve. For example: What sort of regularities are there in the mutation process that generates molecular-level variation? What role does natural selection play, especially in places where traditionally we do not expect it to be very effective?

Systematics

My current funding comes from the National Science Foundation (grant DEB 0075306), for a project to study the phylogeny of rodents. Rodents comprise very nearly one half of all species of mammals, yet the basic pattern of divergences at the base of the rodent family tree are still a mystery. Using sequence data from portions of several nuclear genes (currently, Recombination Activating Gene 2, Interphotoreceptor Retinol Binding Protein, Cannabanoid receptor type 2, von Willebrand factor, and c-Myc) I am using methods including parsimony and maximum likelihood to infer rodent phylogeny.

In addition, I am using these data to address several questions about the process of molecular evolution:

Are “silent” sites under the influence of natural selection?

Are rodents really evolving 5-10 times as fast as primates, and, if so, why?

Does the pattern of natural selection on protein sequence remain constant, or does it vary substantially over time?

In addition to the bench-work of the rodent phylogeny project, I also maintain an active research program in the area of phylogenetic methodology. My primary interest is not so much in development of new tools, but rather in a careful evaluation of how the tools we commonly use are likely to perform in the real world. These studies make use of both real data and simulations.

Molecular evolution

In the area of molecular evolution, I am currently focusing on the question of codon usage bias in the mammalian genome. The genetic code has 64 words, but only needs to encode 21 messages (the 20 amino acids plus stop). Therefore, each amino acid is encoded by between one and six functionally equivalent codons. It might seem logical that any one amino acid in a protein would be encoded by a randomly chosen codon, yet nearly all organisms show a distinct bias in favor of some codons and against others. Considerable evidence supports a hypothesis that codon bias is controlled by natural selection in bacteria and yeast. Specifically, there appears to be a coevolution between codons and transfer RNAs - the most commonly used codon corresponds to the most abundant tRNA. This selective interaction is weak, so the impact of selection should be a function of the effective population size. Bacteria and mammals are likely to have population sizes differing by several orders of magnitude, so it is surprising that the magnitude of codon-usage bias is nearly the same in mammals as it is in bacteria.

Population Biology of Colonial Spiders (collaboration with George Uetz)

Social behavior is extremely rare in spiders, but studies of the few species that are an exception to the rule have yielded valuable insights and provided new model organisms with which to test hypotheses about the evolution of sociality. We are currently studying the facultatively group-living species Metepeira spinepes from several localities on the central coast of California.

In my lab, we are examining the relatedness among colony members, between colonial and solitary individuals, and among and between populations. Preliminary data has been obtained using RAPDs (Randomly Amplified Polymorphic DNAs). We are also currently screening a Metepeira genomic library for microsattelite sequences, which we will use to perform more detailed analyses of relatedness.

(5/14/07) Click here for details on job opportunity as a research associate who will acquire and maintain DNA sequence data

Each Fall term I teach Evolution (Bio 767), which is one of the three “Tier I” courses that form the core of our department’s graduate curriculum. The course starts with a fairly heavy dose of population genetics, intended to get everyone to a point where they can understand and appreciate the differences between Fisher's view of natural selection and Sewell Wright's shifting balance theory. From there, we cover a variety of topics, including adaptation, sexual selection, speciation, and the comparative method.

Each Spring term I teach an advanced graduate course. In even years it is Bio 888, Molecular Evolution, and in odd years it is 876, Phylogenetic Systematics.

Dr. DeBry's Links Page is also available.

	Ronald W. DeBry Associate Professor Ph.D., Michigan State University Molecular Evolution, Molecular Systematics

Address: Ronald DeBry Department of Biological Sciences, ML006 University of Cincinnati Cincinnati, Ohio 45221-0006	Telephone: (513) 556-9743 FAX: (513) 556-5299 Email: Ron.DeBry@UC.Edu