Systematics Section / ASPT
Gruenstaeudl, Michael , Stuessy, Tod F. , Urtubey, Estrella .
Phylogenetic relationships in Barnadesioideae revisited.
Subfamily Barnadesioideae is sister to all other Asteraceae and of importance for our understanding of character evolution in the family. It consists of 91 species in nine genera, all restricted to South America and mainly distributed in xeric habitats along the Andes mountains and in the Patagonian steppe. Its monophyly is clearly defined by both morphological and molecular synapomorphies, such as paired axillary spines, pseudobilabiate corollas, "barnadesioid" floral hairs, and the absence of two combined DNA inversions located in the large single-copy region of the chloroplast genome. Several morphological, palynological, and biogeographical studies, as well as DNA sequence variation in ITS and trnL intron have resulted in highly conflicting phylogenies. A comprehensive molecular phylogeny on the genus level, therefore, is needed. Based on two coding and two non-coding chloroplast markers, sequence variation analysis confirms the previous molecular phylogeny and indicates the necessity of taxonomic reassessment. The hypothesis of the monotypic genus Schlechtendalia being basal within the subfamily, though having the lowest chromosome number (n = 8), is not upheld on molecular grounds. Variability in pollen structure, when plotted on the molecular phylogeny, is congruent with generic relationships; variations in floral characters, in contrast, are homoplasious. At least two independent polyploidisation events must have occurred in the subfamily, and hummingbird pollination originated several times. The dichotomy between Barnadesioideae and all other members of Asteraceae is reiterated, as is the position of the South American family Calyceraceae as sister to Compositae.
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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, Institute for Botany, Dept. of Higher Plant Systematics and Evolution, Rennweg 14, Vienna, A-1030, Austria
3 - Museo De La Plata, Department Cient. Plantas Vasculares, Museo De La Plata, Paseo Del Bosque S/N, La Plata, Buenos Aires, 1900, Argentina
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Erie/Hilton
Date: Monday, July 9th, 2007
Time: 3:15 PM