About Dr. Mason-Gamer's Research

As a plant systematist, I am interested in the evolutionary processes that lead to divergence among plants, and in the phylogenetic patterns that describe relationships among them. Within this broad area, I am especially interested in using molecular genetic techniques to study phylogenetic relationships among closely related species. At this level, taxa have begun to diverge, yet often still show evidence of past or ongoing gene exchange. Closely related taxa, therefore, may show a reticulate pattern of evolution, a situation in which two divergent branches on the phylogenetic tree of life appear to have merged back together. Reticulate patterns may result from the maintenance of gene diversity from ancestral populations (lineage sorting) or from explicitly reticulating processes such as hybridization, allopolyploidy, or horizontal gene transfer. In some reticulate groups, a combination of these may give rise to observed patterns. Obtaining evidence for reticulate evolution often requires detailed comparisons among multiple phylogenetic data sets, and this has led to my interest in the philosophy and methodologies that underlie such comparisons.

Much of my current research involves the grass family, with a particular emphasis on the wheat tribe (Triticeae). Comparisons among diploid genera in this economically important group show strong evidence of gene exchange, even though the genera are currently intersterile. More recently, phylogenetic studies of allopolyploids have helped to identify their parental genome donors, and with studies now underway, I hope to further address the relationships between allopolyploids and their related diploids, as well as the complicated relationships among the allopolyploid species.

For more specific information about ongoing projects, go to my research page, or go to the lab page and visit the members of the lab.

Representative Publications

Mason-Gamer, R. J., M. Naum, and M. M. Burns. 2009. Phylogenetic relationships and reticulation among Asian Elymus (Poaceae) allotetraploids: Analyses of three nuclear gene trees. Molecular Phylogenetics and Evolution in press.

Mason-Gamer, R. J. 2008. Allohexaploidy, introgression, and the complex phylogenetic history of Elymus repens (Poaceae). Molecular Phylogenetics and Evolution 47:598-611.

Mason-Gamer, R. J. 2007. Allopolyploids of the genus Elymus (Triticeae, Poaceae): a phylogenetic perspective. Aliso 23:372-379.

Mason-Gamer, R. J. 2007. Multiple homoplasious insertions and excisions of a Triticeae (Poaceae) DNA transposon: a phylogenetic perspective. BMC Evolutionary Biology 7:92.

Mason-Gamer, R. J. 2005. The ß-amylase genes of grasses and a phylogenetic analysis of the Triticeae (Poaceae). American Journal of Botany 92:1045–1058.

Helfgott, D. M. and R. J. Mason-Gamer. 2004. The evolution of North American Elymus (Triticeae, Poaceae) allotetraploids: evidence from phosphoenolpyruvate carboxylase gene sequences. Systematic Botany 29:850–861.

Mason-Gamer, R. J. 2004. Reticulate evolution, introgression, and intertribal gene capture in an allohexaploid grass. Systematic Biology 53:25–37.