Systematics Section / ASPT
Tripp, Erin A. , Manos, Paul S. .
Systematics of Ruellia (Acanthaceae): a first look at evolutionary relationships within a species-rich genus.
THE genus Ruellia is pantropical and mostly herbaceous, and belongs to one of four major lineages with the Acanthaceae (ca. 4,000 species): tribe Ruellieae. Though Ruellia is the second largest genus in the family, with approximately 300 species, little was previously known about phylogenetic relationships among species, or relationships among the ca. 800 species that comprise Ruellieae. Thus, this study represents the first investigation of evolutionary relationships in this species-rich lineage, using molecular data. Sequences from nearly 125 species of Ruellia, plus 25 additional species from other genera in Ruellieae, were generated for the nuclear ITS and chloroplast trnG-trnR regions. Bayesian and parsimony analyses were conducted to test the monophyly of Ruellia, resolve species relationships, re-consider previous taxonomic classifications, and to permit character evolution analyses. Results suggest that this large and morphologically diverse genus is likely monophyletic and contains several major clades that can, to some degree, be identified using suites of morphological synapomorphies. Parallel evolution is rampant in Ruellia, with preliminary ancestral reconstructions suggesting that hummingbird, bat, bee, and hawkmoth pollination have all evolved multiple times, as have tree and liana habits. Further, there exists a possible correlation between plant habit and pollination syndrome, such that evolutionary transitions in habit may have permitted subsequent exploitation of new pollinators. Ongoing work on pollination syndrome transitions in Ruellia will undoubtedly reveal interesting patterns of floral character change, as well as whether and how pollinators have been an important selective force in the overall diversification of the genus. This work also contributes to our growing understanding of systematic relationships within Acanthaceae, and how plants and their pollinators have interacted through evolutionary time.
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1 - Duke University, Department of Biology, 139 Biological Sciences Building, PO Box 90338, Durham, North Carolina, 27708, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 31st, 2006
Time: 9:00 AM