Department of Biology

Awards

George R. Cooley Award, American Society of Plant Taxonomists
Fellow, Indiana Academy of Science

Research

Our work focuses on three broad areas: Evolution of the Lobeliaceae and Cyphiaceae; Plastid and mitochondrial genome evolution; Documenting the flora of Indiana.

The Lobeliaceae and Cyphiaceae are closely related, mid-sized families of flowering plants. The Lobeliaceae (1200 species in 31 genera) are nearly cosmopolitan and are particularly diverse in temperate and high-altitude tropical areas. The Cyphiaceae (75 species in the genus Cyphia) are restricted to Africa. Biogeographic reconstruction indicates that both families originated in Southern Africa, with repeated patterns of diversification from the winter-rainfall areas of the Western Cape to the summer-rainfall areas to the east, then north to the highlands of eastern Africa, with repeated dispersal to the West African highlands, Madagascar, and (for the Lobeliaceae) elsewhere in the world. Lobelia is the 'core genus' of the Lobeliaceae, from which the remaining segregate genera evolved. The plastid DNA-based phylogenetic estimate for these two families now includes over 900 samples, but additional work is needed to complete the sampling of all major groups. In addition to the biogeographic reconstruction, this phylogenetic estimate permits reconstruction of morphological evolution, particularly the derivation of giant lobelias from herbaceous ancestors, and evolution of the reproductive features used to delimit the segregate genera.

The Lobeliaceae and Cyphiaceae also show extensive rearrangements in their plastid genomes (the chloroplast is one developmental form of the plastid), which is unusual in angiosperms. Over 200 of these plastid genomes have been sequenced in order to understand the molecular basis of this structural instability. The surprising discovery is that these plastid genomes have been repeated invaded by foreign genes, and the integration of these foreign DNA sequences caused many of the rearrangements. Certain groups of Lobeliaceae also show accelerated rates of mitochondrial DNA sequence evolution. Completely sequenced mitochondrial genomes from representatives of the fast and slow groups show that the rapidly evolving mitochondrial genomes are vastly enlarged and fragmented into separate circular chromosomes.

The Indiana University Herbarium (IND) is the main repository for the specimens collected by Charles Deam, upon which he based his 1940 book Flora of Indiana. In 2019, IND completed a five-year project to digitize the 161,000+ specimens in the collection. The vascular plant information is available through the Consortium of Midwest Herbaria (CMH) data portal, with other portals for the algae, lichens, bryophytes, and fungi. The data portals have advanced search features, identification tools, and photographs of the living organisms. The information can be viewed online or downloaded in various ways.

Research areas

Evolution
Genomics and Bioinformatics
Plant Molecular Biology