Systematics Section / ASPT
Smith, Stacey D. , Baum, David A. .
Floral diversification despite hybridization in the Andean clade Iochrominae (Solanaceae).
Iochrominae, a clade of 35 Andean species nested in Physaleae sensu Olmstead et al. 1999, exhibits an immense floral diversity, including shapes and colors that are not found in related lineages and uncommon in Solanaceae as a whole. To place the acquisition of these novel traits in an evolutionary framework, we generated a phylogeny of Iochrominae using three nuclear regions, ITS, the second intron of LFY and the granule-bound starch synthase gene (waxy). We sampled 33 of the 35 known species of Iochrominae along with representatives of six genera in Physaleae and four far outgroups (Capsicum, Lycianthes, Solanum and Nicandra). Floral morphology was found to be extremely labile with multiple convergences on similar combinations of form and color. Since the taxonomic division of Iochrominae into six genera was largely based on floral characters, all genera but one were rendered non-monophyletic. In addition, comparison of the nuclear datasets revealed two clear cases of interspecific hybrid formation. Examination of plastid DNA variation at the trnL-trnF intergenic spacer corroborated the occurrence of hybridization and introgression across the phylogeny. However, the leakiness of species boundaries in this group has clearly not hindered its diversification, perhaps due to pollinator-mediated selection coupled with the potential for microallopatry in montane Andean habitats.
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Baum Lab Website
1 - University of Wisconsin Madison, Department of Botany, Birge Hall, 430 Lincoln Drive, Madison, Wisconsin, 53706-1381, USA
nuclear gene phylogeny
Presentation Type: Oral Paper
Location: Salon G - Austin Grand Ballroom/Hilton
Date: Wednesday, August 17th, 2005
Time: 1:45 PM