Thomas J. Givnish


Henry Allan Gleason Professor of Botany and Environmental Studies

Ph.D. (1976) Princeton University • 315 Birge Hall • 608-262-5718 •

Plant ecology and evolution; adaptive radiation and molecular systematics;
phylogeography; physiological ecology; landscape dynamics

Phylogeography - the geographic pattern of differentiation within species or closely related taxa - is an important emerging field, bridging population processes with phylogeny and biogeography. 

We are studying phylogeography and the spatial scales of genetic differentiation in the Bay Area clade of Calochortus, to determine whether species endemic to serpentine have been derived from within more widely ranging, non-serpentine species, and whether poor seed dispersal has led to genetic differentiation at small spatial scales, culminating in high species diversity, geographic cohesion of lineages, and parallel adaptive radiations in several traits across Calochortus as a whole.

As part of a $3M NSF grant on the determinants of local plant extinction and invasion in Wisconsin, we are investigating the spatial scale of genetic differentiation and apparent gene flow in some 40 “winner” and “loser” species. Our aim is to use these data as proxies for overall mobility and incorporate them in models for future species loss and spread. Dr. Rebecca Kartzinel is using next-generation sequencing to characterize variation in RAD-SEQ markers in several populations per species and reconstruct spatial genetic structure.

Recent Ph.D. Terra Theim used AFLPs to examine the geographic scales of genetic differentiation and apparent gene flow in understory species of Psychotria to confirm the hypothesis that understory tropical trees with fleshy fruits differentiate at small spatial scales – and ultimately contribute a remarkably high fraction of rain-forest tree diversity – because they rely on sedentary forest-interior birds for seed dispersal.

Photographs:  TOP - Portrait of the scientist as a young man among Nymphaea; sandstone escarpment, Auyán-tepui, one of the many plateaus of the Guayana Shield and home to many narrow endemics; Calochortus pulchellus (Liliaceae), member of a species-rich genus characterized by seeds with no apparent means of long-distance dispersal; and Trillium flexipes (Melanthiaceae), a wide-ranging, Midwestern element of the Trillium erectum complex, including several narrow endemics from the southern Appalachians. Photograph of Calochortus pulchellus © 2000 Robert M. Case, reprinted with permission.

© 2011 University of Wisconsin Department of Botany

Last updated: 27 November 2011