Weiss-Schneeweiss, Hanna , Schneeweiss, Gerald M. , Blöch, Cordula , Rebernig, Carolin A. , Stuessy, Tod F. .
Dysploid and polyploid chromosome number changes and reticulate evolution drive the diversification of Melampodium (Millerieae, Asteraceae).
Chromosome evolution (including polyploidy, dysploidy, and structural changes) as well as hybridization and introgression are recognized as important aspects in plant speciation. A suitable group for investigating the evolutionary role of chromosome number changes and reticulation is the medium-sized mainly Mexican genus Melampodium (Millerieae, Asteraceae), which contains several chromosome base numbers (x = 9, 10, 11, 12, 14) and a number of polyploid species, including putative allopolyploids. Molecular phylogenetic analysis including all 40 species of the genus suggests that chromosome base numbers are predictive of evolutionary lineages within Melampodium, emphasizing the role of dysploidy for the evolution of the group. Reticulate evolution is evident with allopolyploids, which prevail over autopolyploids and whose origin has been confirmed by DNA sequence and caryological data, and also (but less often) on the diploid level. Within sect. Melampodium, the complex pattern of bifurcating phylogenetic structure among diploid taxa overlain by reticulate relationships from allopolyploids has non-trivial implications for intrasectional classification.
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1 - University of Vienna, Institute for Botany, Dept. of Higher Plant Systematics and Evolution, Rennweg 14, Vienna, A-1030, Austria
2 - University of Vienna, Department of Biogeography, Rennweg 14, Vienna, Vienna, A-1030, Austria
3 - University of Vienna, Department of Systematic and Evolutionary Botany, Rennweg 14, Vienna, Wien, A-1030, Austria
4 - University of Vienna, Department of Higher Plant Systematics and Evolution, Rennweg 14, Vienna, Vienna, A-1030, Austria
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Cottonwood D/Snowbird Center
Date: Wednesday, July 29th, 2009
Time: 11:45 AM