My research explores the evolutionary and ecological processes that contribute to plant diversity. In particular, the study of reticulate evolution, including polyploidy/whole genome duplication, hybridization, and introgression, forms the central organizing principle of my research program. The importance of these phenomena in shaping the evolutionary trajectories of many plant lineages is now widely recognized, though the specific effects of reticulation on patterns of relationships and biogeography, organization of post-hybridization genomes, and physiological ecology of hybrids are still largely unexplored. My work bridges a diverse set of disciplines in order to gain insight into the numerous ways in which reticulate processes shape plant evolution. I utilize a variety of study systems, but with a strong focus on seed-free vascular plants, the ferns and lycophytes.
Sessa EB, Givnish TJ. In press. Leaf form and
photosynthetic physiology of Dryopteris species distributed along
light gradients in eastern North America. Functional Ecology.
Sessa EB, Zimmer EA, Givnish TJ. 2012. Unraveling
reticulate evolution in North American Dryopteris (Dryopteridaceae).
BMC Evolutionary Biology 12(1): 104
Sessa EB, Zimmer EA, Givnish TJ. 2012. Reticulate
evolution on a global scale: a nuclear phylogeny for New World
Dryopteris (Dryopteridaceae). Molecular Phylog & Evolution
Sessa EB, Zimmer EA, Givnish TJ. 2012. Phylogeny,
divergence times, and historical biogeography of New World
Dryopteris (Dryopteridaceae). American Journal of Botany 99
Zhang L-B, Zhang L, Dong S-Y, Sessa EB, Gao X-F, Ebihara A.
2012. Molecular circumscription and major evolutionary lineages of
the fern genus Dryopteris (Dryopteridaceae). BMC Evolutionary
Biology 12(12): 180.