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. We are using AFLPs, a rapidly evolving and hypervariable set of genetic markers, as well as plastid and nuclear gene sequences to track genetic variation within and among Calochortus populations in northern California.

Recent Ph.D. Terra Theim examined the geographic scale of genetic differentiation in gap vs. understory species of Psychotria to test the hypothesis that understory tropical trees with fleshy fruits differentiate and speciate 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. I am interested in recruiting a student to analyzed the spatial scales of genetic differentiation and incipient mating barriers in the Hawaiian lobeliads as well.

Kendra Millam is studying the phylogeography of the Trillium erectum complex, reconstructing the historical biogeography of this hallmark lineage of the southern Appalachians. Melissa Chung recently completed a phylogeographic study of the Oxytropis chartacea complex in eastern North America, showing that the federally endangered Fassett's locoweed (O. chartacea var. campestris) is most closely related to populations in Maine and the Maritime Provinces of Canada, and that all of these populations are closely related to some along the southern shore of Hudson Bay.