Givnish, Thomas J. , Theim, Terra J. , Henss, Jillian M. .
Phylogeography of the Bay Area clade of Calochortus (Liliaceae).
CALOCHORTUS has undergone extensive speciation and parallel radiations in floral syndrome, habitat, and substrate type in seven major lineages, centered in different geographic areas, mostly in the California Floristic Province. The Bay Area clade includes ten species (Calochortus albus, C. amabilis, C. amoenus, C. monophyllus, C. pulchellus, C. raichei, C. tiburonensis, C. tolmiei, C. umbellatus, C. uniflorus) that range into the Coastal Ranges, western foothills of the Sierra Nevada, Siskiyous, and (in Oregon) the Cascades. We quantified phylogeographic relationships in this group using AFLP variation, building on an earlier species-level phylogeny based on plastid DNA sequences. The plastid phylogeny implied a remarkable degree of divergence in floral syndromes (fairy lanterns, cat’s ears, star tulips) among close relatives. While the AFLP and plastid trees agree in many respects, conflicts identify at least three species as being of hybrid origin. Where the AFLP and plastid trees differ, the (nuclear) AFLP tree groups species similar in form (e.g., the fairy-lantern species) while the plastid tree groups species of neighboring distributions, suggesting the likelihood of chloroplast capture. Populations of the wide-ranging Calochortus albus from the Coastal Ranges show substantial differentiation from those on the western slopes of the Sierra Nevada; genetic distance and geographic distance are significantly correlated with each other in this species, with genetic differentiation occurring at relatively small geographic scales, supporting our hypothesis that limited seed dispersal leads to genetic differentiation – and ultimately speciation and narrow endemism – at small spatial scales. Several fairy-lantern species appear to form a ring-species complex around the Central Valley.
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1 - University of Wisconsin Madison, Department of Botany, Birge Hall, 430 Lincoln Drive, Madison, Wisconsin, 53706-1381, USA
Presentation Type: Oral Paper:Papers for Topics
Location: 134/Performing Arts Center
Date: Wednesday, August 2nd, 2006
Time: 10:30 AM