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Abstract Detail

Systematics Section/ASPT

Liu, Shih-Hui [1], Hoch, Peter [2], Raven, Peter [3], Barber, Janet [4].

Polyploid evolution in Ludwigia section Macrocarpon(Onagraceae): preliminary insights.

Polyploidy has long been recognized as a crucial force in plant evolution and has also been suggested as a contributing factor in invasiveness. While the understanding of polyploid evolution of a few model organisms is being improved, the role of polyploidy in the evolution of non-model organisms remains poorly understood. Increased variation of traits in polyploid taxa may enable them to adapt to different habitats and contribute to invasion success. The pan-subtropical genus Ludwigia L. (Onagraceae), currently comprising 82 species in 23 sections, exhibits extensive polyploidy and plays important roles in ethnobotany and ecology. Earlier studies have clearly established that Ludwigia is monophyletic and is sister to the remaining genera in the family, but a robust reconstruction of evolutionary relationships within Ludwigia is incomplete. In this study, we are continuing the phylogenetic study of Ludwigia, especially focusing on characterizing polyploid evolution in section Macrocarpon based on both molecular and morphological data. Section Macrocarpon is an ideal group for studying polyploid evolution because it includes self-incompatible diploid taxa (Ludwigia bonariensis and L. lagunae; n=8) with limited distributions, as well as a self-compatible (sometimes autogamous) polyploid species (L. octovalvis; n=8, 16, 24) with worldwide distribution that has become invasive in some regions. In the past two years, we have extended earlier phylogenetic studies of Ludwigia using the same chloroplast and nuclear DNA markers for 25 additional taxa of Ludwigia and one additional outgroup, with a focus on increased sampling within section Macrocarpon. Our current phylogenetic tree includes about 40% of species and half of sections in Ludwigia and strongly supports section Macrocarpon as monophyletic. Moreover, our morphological analyses suggest that tetraploid and hexaploid L. octovalvis can be identified by their pollen sizes, though there is considerable variability in other traits.

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1 - Saint Louis University, Biology, 3507 Laclede Avenue, St. Louis, MO, 63103, USA
2 - Missouri Botanical Garden, P.O. Box 299, St. Louis, MO, 63166-0299, USA
3 - Missouri Botanical Garden, 2345 TOWER GROVE, St. Louis, MO, 63110, USA
4 - Saint Louis University, Department of Biology, 3507 Laclede Avenue, St. Louis, MO, 63103, USA


Presentation Type: Poster:Posters for Sections
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:30 PM
Number: PSY073
Abstract ID:148
Candidate for Awards:Genetics Section Poster Award

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