Director, Indiana University Herbarium

Ph.D., University of Michigan, 1993

Program Affiliation: Evolution, Ecology and Behavior | Molecular Biology & Genetics | Plant Biology

Research Groups Affiliation: Evolution | Genetics | Plant Biology

George R. Cooley Award, American Society of Plant Taxonomists

Phone: 812/855-2549 or -5007
Fax: 812/855-6705
Email Eric

Our work focuses on three broad areas: Evolution of the Lobeliaceae and Cyphiaceae; Horizontal gene transfer in Amborella trichopoda ; 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 DNA-based phylogenetic estimate for these two families now includes over 650 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.   These families also show extensive rearrangements in their chloroplast genomes, which is unusual in angiosperms.   We are in the process of sequencing 50 of these chloroplast genomes in order to understand the molecular basis of this structural instability.   Certain groups of Lobeliaceae also show accelerated rates of mitochondrial DNA sequence evolution, and we are sequencing the mitochondrial genomes from representatives of the fast and slow groups.

Amborella trichopoda is a small tree that grows in the rainforest of New Caledonia.   The sole member of its genus and family, A. trichopoda has long been recognized as an unusual plant with several morphological features thought to be primitive in the evolution of flowering plants.   Although several other groups of plants were similarly regarded as 'relics' of early angiosperm evolution, Amborella is possibly the single surviving species of a lineage that is sister to all other flowering plants.   Even more surprising, the mitochondrial genome of Amborella is about three times the normal size and contains many foreign copies of mitochondrial genes that were acquired by horizontal gene transfer from various donor that include other angiosperms and mosses.   We are sequencing the mitochondrial genome of Amborella , and we recently completed the first phase of fieldwork in New Caledonia in order to collect the potential donors of these horizontally transferred genes.

The Indiana University Herbarium (IND) is the main repository for the specimens collected by Charles Deam, upon which he based his 1940 book The Flora of Indiana .   We are working to update the taxonomy and distribution information for the native and naturalized species of vascular plants in Indiana, and to make this information widely available through a fully searchable website known as the Indiana Botanical Information System (IBIS).   Once IBIS is implemented, a variety of research and educational modules will be developed to help make this information accessible to a wide range of potential users.

Knox, E. B.   2005.   Dendrosenecio .   Pp. 548-563 in H. J. Beentje, C. Jeffrey & D. J. N. Hind (eds.), Flora of Tropical East Africa, Compositae (part 3, pp. 547-869).   Royal Botanic Gardens, Kew, U.K.

Knox, E. B., Q. Luke, and M. Thulin.   2004.   A new giant Lobelia from the Eastern Arc Mts, Tanzania.   Kew Bull. 59: 189-194.

Knox, E. B.   2004   Adaptive radiation of African montane plants.   Pp. 345-361 in U. Dieckmann, M. Doebeli, J. A. J. Metz, and D. Tautz (eds.), Adaptive Speciation .   Cambridge University Press, Cambridge.

Phillipson, P. B., and E. B. Knox.   2003.   Lobeliaceae.   Pp. 604-612 i n G. Germishuizen and N. L. Meyer (eds.), Plants of southern Africa: an annotated checklist .   Strelitzia 14.   National Botanical Institute, Pretoria.

Knox, E. B.   1999.   Reconstruction of adaptive radiation in insular habitats using integrated biogeographic information.   J. Biogeogr. 26: 983-992.

Knox, E. B., and J. D. Palmer.   1999.   The chloroplast genome arrangement of Lobelia thuliniana (Lobeliaceae ): expansion of the inverted repeat in an ancestor of the Campanulales .   Pl. Syst. Evol. 214: 49-64.

Knox, E. B., and J. D. Palmer.   1998.   Chloroplast DNA evidence on the origin and radiation of the giant lobelias in eastern Africa.   Syst. Bot. 23: 109-149.

Knox, E. B.   1998.   The use of hierarchies as organizational models in systematics.   Biol. J. Linn. Soc. 63: 1-49.

Knox, E. B., and J. D. Palmer.   1995.   Chloroplast DNA variation and the recent radiation of the giant senecios (Asteraceae) on the tall mountains of eastern Africa.   Proc. Natl. Acad. Sci. USA 92: 10349-10353.

Knox, E. B., S. R. Downie, and J. D. Palmer.   1993.   Chloroplast genome rearrangements and the evolution of giant lobelias from herbaceous ancestors.   Molec. Biol. Evol. 10: 414-430.