| Abstract Detail
Thursday Morning Contributed Talks Smith, Stacey [1], Baum, David [1]. Systematics of Iochrominae (Solanaceae): Dual challenges of diversification and hybridization. IOCHROMINAE is a florally diverse clade of 34 Andean species, traditionally divided among 6 genera. Recent plastid and nuclear phylogenetic analyses have clarified that Iochrominae is a member of Physaleae and is likely to be sister to Physalinae (sensu Olmstead et al., 1999). While the vast majority of taxa within Physaleae have small, white or yellow, rotate flowers, Iochrominae flowers may be red, orange, yellow, green, blue, purple or white and the corolla may be rotate, campanulate, infundibuliform or tubular. Moreover, flower length varies by a factor of eight-fold across taxa. A phylogeny derived from three nuclear loci reveals multiple instances of convergence in color and form. Because the traditional taxonomic schemes for Iochrominae have relied mainly on the apparently labile floral characters, all genera but one appear to be non-monophyletic. An additional challenge in the taxonomy of this group is the occurrence for interspecific hybridization. Comparison of the nuclear loci suggests that at least two, and possibly more accessions are the products of hybridization events. Examination of plastid DNA variation in the trnL-trnF intergenic spacer corroborates the occurrence of introgression and hybridization across the phylogeny. Greenhouse crosses show that species from quite distantly related lineages of Iochrominae can yield viable hybrids. These results suggest that the speciation and diversification of Iochrominae has not been accompanied by the formation of strong barriers to gene exchange. However, pre-mating factors, such as allopatry and ethological isolation, and post-mating factors, such as reduced hybrid fitness, might have together acted to maintain the morphological and evolutionary cohesiveness on the clades and species of Iochrominae.
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1 - University of Wisconsin-Madison, Department of Botany, 132 Birge Hall, 430 Lincoln Dr., Madison, WI, 53706, USA
Keywords:
interspecific hybridization
nuclear gene phylogeny
floral morphology
convergence.
Session: SOL06-5
Location: Ballroom AB/Monona Terrace
Date: Thursday, July 27th, 2006
Time: 9:30 AM
Abstract ID:47 |
