Mathews, Katherine , Ruigrok, Michelle , Mansion, Guilhem .
Phylogeny and trait evolution in Sabatia (Gentianaceae) and uneven diversification rates in subtribe Chironiinae.
Sabatia (Gentianceae, subtribe Chironiinae) is an herbaceous, eastern U.S., primarily coastal plain group of flowering plants. Previous phylogenetic analyses within Sabatia employing three chloroplast noncoding regions and one nuclear rDNA region resolved five well-supported clades, but relationships among these clades were not resolved. The addition of a fourth noncoding cpDNA region and a new species suspected of being an early-evolving lineage greatly increases resolution at the base of the phylogeny. We find evidence for single origins of both stable floral polymery and white corollas from the ancestral conditions of pentamerous flowers and pink corollas, respectively. Autogamy has evolved twice in this primarily outcrossing genus and appears unrelated to ploidy, but rather to adaptation to ephemeral habitats. Sabatia is characterized by high levels of aneuploidy, which may be responsible for speciation, along with geographical isolation and ecological specialization. The most ancestral species, S. arenicola and S. campetris, have the lowest chromosome numbers in the genus, and ploidy increases throughout the genus. Sabatia (20 species) shows greater species richness than its sister genera, Gyrandra (5 species) and Eustoma (3 species). We explore shifts in diversification rates in subtribe Chironiinae with respect to trait evolution in the group.
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1 - Western Carolina University, 132 NATURAL SCIENCE BUILDING, CULLOWHEE, NC, 28723, USA
2 - Highlands Biological Station, 265 N. Sixth Street, Highlands, NC, 28741, USA
3 - Botanischer Garten und Botanisches Museum Berlin-Dahlem, Freie Universität Berlin, Königin-Luise-Straße 6 - 8, 14195 Berlin, Germany
Presentation Type: Oral Paper:Papers for Sections
Location: Lindell A/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 2:00 PM