Systematics Section / ASPT
Levin, Rachel , Miller, Jill S. .
Relationships within tribe Lycieae: paraphyly, gender dimorphism, fruit evolution and biogeography.
TRIBE Lycieae (Solanaceae) includes three genera: Grabowskia, Lycium, and Phrodus. Lycium is the largest genus, with ca. 80 species distributed worldwide, and centers of diversity in South America, southwestern North America, and southern Africa. We examine phylogenetic relationships among and within these three genera using DNA sequence data from the nuclear granule-bound starch synthase gene (GBSSI, waxy) and the chloroplast region trnT-trnF. Data suggest that although tribe Lycieae is strongly monophyletic, Grabowskia and the monotypic Phrodus microphyllus are nested within Lycium. As in many Solanaceae, tribe Lycieae most likely originated in South America. Our data indicate frequent dispersal between North and South America, and a single dispersal event from the Americas to the Old World. In addition, we show that the evolution of gender dimorphism in Lycium is convergent within the genus, having occurred at least twice in North America and several times in southern Africa, although determination of the exact number of such shifts is complicated by data set incongruence. Most Lycium species have red berries when ripe and are attractive to birds. However, other Lycium species have few-seeded, hardened fruits and are similar to Grabowskia (also with hardened fruits). The diversity of fruit types in Lycieae is discussed in light of dispersal patterns and recent work on fruit evolution across Solanaceae. Results of this study will provide the basis for a revised classification of genera within the tribe.
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1 - Amherst College, Department of Biology, Mcguire Life Sciences Building, Amherst, Massachusetts, 01002, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, August 2nd, 2006
Time: 8:00 AM