Systematists and molecular phylogeneticists study the patterns and processes of organismal diversity, from the gene to the organism to the clade level, and ask questions focused on how the diversity we see has originated, and how different processes have led to these diversification patterns. Integration of studies across these different hierarchical levels is important to understand not only how lineages have diversified, and how they might be classified, but also what processes might have been important. My research has focused on two general questions: (1) what are the patterns of angiosperm diversity, from species boundaries to clade classifications to historical biogeography; and (2) what are the evolutionary dynamics of morphological and physiological traits (and their underlying genes) important to diversification, particularly floral structural changes and photosynthetic pathway modification. Current projects focus on the Cyperaceae, Gesneriaceae, Cleomaceae, and Chenopodiaceae, with studies exploring a variety of phylogenetic, cytogenetic, morphological, and physiological questions.
Rosnow, J. J., G. E. Edwards, and E. H. Roalson. 2014. Positive selection of Kranz and non-Kranz C4 phosphoenolpyruvate carboxylase amino acids in Suaedoideae (Chenopodiaceae). Journal of Experimental Botany. Published online March 5, 2014 doi:10.1093/jxb/eru053
Akhani, H., W. Greuter, and E. H. Roalson. 2014. Notes on the typification and nomenclature of Salsola and Kali (Chenopodiaceae). Taxon. Published online June 2, 2014 doi: http://dx.doi.org/10.12705/633.1
Patchell, M. J., E. H. Roalson, and J. C. Hall. 2014. Resolved phylogeny of Cleomaceae based on all three genomes. Taxon 63: 315–328.
Jiwan, D., E. H. Roalson, D. Main, and A. Dhingra. 2013. Antisense expression of peach mildew resistance locus O (PpMlo1) gene confers cross-species resistance to powdery mildew in Fragaria x ananassa. Transgenic Research 22: 1119–1131.
Riser II, J. P., W. M. Cardinal-McTeague, J. C. Hall, W. J. Hahn, K. J. Sytsma, and E. H. Roalson. 2013. Phylogenetic relationships among the North American cleomoids (Cleomaceae): A test of Iltis' reduction series. American Journal of Botany 100: 2102–2111.
Voznesenskaya, E. V., N. K. Koteyeva, H. Akhani, E. H. Roalson, and G. E. Edwards. 2013. Structural and physiological analyses in Salsoloideae (Chenopodiaceae) indicate multiple transitions among C3, intermediate, and C4 photosynthesis. Journal of Experimental Botany 64: 3583–3604.
Hinchliff, C. E. and E. H. Roalson. 2013. Using supermatrices for phylogenetic inquiry: an example using the sedges. Systematic Biology 62: 205–219.
Chung, K.-S., A. L. Hipp, and E. H. Roalson. 2012. Chromosome number evolves independently of genome size in a clade with non-localized centromeres (Carex: Cyperaceae). Evolution 66: 2708–2722.
Clark, J. L., E. H. Roalson, R. A. Pritchard, C. L. Coleman, V.-H. Teoh, and J. Matos. 2011. Independent origin of radial floral symmetry in the Gloxinieae (Gesnerioideae: Gesneriaceae) is supported by the rediscovery of Phinaea pulchella in Cuba. Systematic Botany 36: 757–767.
Koteyeva, N. K., E. V. Voznesenskaya, E. H. Roalson, and G. E. Edwards. 2011. Diversity in forms of C4 which evolved in genus Cleome (Cleomaceae). Annals of Botany 107: 269–283.
Roalson, E. H. 2011. C4 photosynthesis origins in the monocots: a review and reanalysis. Pp. 319–338 in C4 Photosynthesis and Related CO2 Concentrating Mechanisms. Raghavendra, A. S. and R. F. Sage (eds.). Dordrecht, The Netherlands, Kluwer.
Feodorova, T., E. V. Voznesenskaya, G. E. Edwards, and E. H. Roalson. 2010. Biogeographic patterns of diversification and the origins of C4 in Cleome (Cleomaceae). Systematic Botany 35: 811–826.
Hinchliff, C. E., A. E. Lliully Aguilar, T. Carey, and E. H. Roalson. 2010. The origins of Eleocharis (Cyperaceae) and the phylogenetic position of Websteria, Egleria, and Chillania. Taxon 59: 709–719.
Hinchliff, C. E., S. Petersen, and E. H. Roalson. 2010. Eleocharis endounifascis: A new species of Eleocharis subgenus Limnochloa (Cyperaceae) from northern South America. Phytotaxa 7: 19–24.
Roalson, E. H., C. E. Hinchliff, R. Trevisan, and C. R. M. da Silva. 2010. Phylogenetic relationships in Eleocharis (Cyperaceae): C4 photosynthesis origins and patterns of diversification in the spikerushes. Systematic Botany 35: 257–271.
Skinner, M. K., A. Rawls, J. Wilson-Rawls, and E. H. Roalson. 2010. Basic helix-loop-helix transcription factor gene family phylogenetics and nomenclature. Differentiation 80: 1–8.
Besnard, G., A. M. Muasya, F. Russier, E. H. Roalson, N. Salamin, and P.-A. Christin. 2009. Phylogenomics of C4 photosynthesis in sedges (Cyperaceae): multiple appearances and genetic convergence. Molecular Biology and Evolution 26: 1909–1919.
Clark, J. R., W. L. Wagner, and E. H. Roalson. 2009. Patterns of diversification and ancestral range reconstruction in the Southeast Asian-Pacific angiosperm lineage Cyrtandra (Gesneriaceae). Molecular Phylogenetics and Evolution 53: 982–994.
Hinchliff, C. E. and E. H. Roalson. 2009. Evolution of stem architecture in Eleocharis subgenus Limnochloa (Cyperaceae): evidence of rapid dynamic evolution in a group of pantropical sedges. American Journal of Botany 96: 1487–1499.
Hipp, A. L., P. E. Rothrock, and E. H. Roalson. 2009. The evolution of chromosome arrangements in Carex (Cyperaceae). The Botanical Review 75: 96–109.