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Abstract Detail



Biogeography

Schuster, Tanja [1], Setaro, Sabrina [2], Kron, Kathleen [3].

Age estimates for Polygonaceae Juss. based on sequence data calibrated by fossils: implications for the historical biogeography of the amphi-Pacific Muehlenbeckia Meisn.

The buckwheat family Polygonaceae is a diverse group of plants and is a good model for investigating hypotheses concerning biogeography, breeding systems, functional trait evolution, hybridization, invasiveness, morphological plasticity, pollen morphology and wood anatomy. The main goal of this study was to obtain age estimates for Polygonaceae by calibrating a Bayesian phylogenetic analysis, using a relaxed molecular clock with fossil data. Based on the age estimates, we also develop hypotheses about the historical biogeography of the Southern Hemisphere group Muehlenbeckia. We are interested in addressing whether vicariance or dispersal account for the diversification of Muehlenbeckia, which has a so called Gondwanan distribution. Eighty-one species of Polygonaceae were analyzed with MrBayes to infer species relationships. One nuclear (nrITS) and three chloroplast markers (the trnL-trnF spacer region, matK and ndhF genes) were used. The molecular data were also analyzed with Beast to estimate divergence times. Seven calibration points including fossil pollen and a leaf fossil of Muehlenbeckia were used to infer node ages. Results of the Beast analyses indicate an age of 110.9 (exponential/lognormal priors)/118.7 (uniform priors) million years (Myr) with an uncertainty interval of (90.7 - 125.0) Myr for the stem age of Polygonaceae. This age is older than previously thought (Maastrichtian, approximately 65.5 - 70.6 Myr). Results for Eriogonoideae and Polygonoideae indicate a split around 97.8/105.5 (78.2 - 122.5) Myr. The estimated divergence time for Muehlenbeckia is 41.0/41.6 (39.6 - 47.8) Myr and its crown clade is 20.5/22.3 (14.2 - 33.5) Myr old. Because the breakup of Gondwana occurred from 95 - 30 Myr ago and clades of Muehlenbeckia with disjunct distributions across e.g. New Zealand and South America are younger than when these landmasses broke apart, long-distance and maybe stepping-stone dispersal rather than vicariance is likely the main driver for diversification within Muehlenbeckia. This study is the first to give age estimates for clades of Polygonaceae and functions as a jumping-off point for future studies on the historical biogeography of the family.

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1 - University of Maryland, Plant Science And Landscape Architecture, Research Greenhouse Complex, Rm. 1114, Terrapin Trail, College Park, MD, 20742, USA
2 - Wake Forest University, Biology, 1834 Wake Forest Road, Winston Hall, Winston-Salem, NC, 27106, USA
3 - Wake Forest University, Department of Biology, 1834 Wake Forest Road, WINSTON-SALEM, NC, 27106, USA

Keywords:
Andes
Australia
ektexine
fire ecology
Miocene
New Guinea
paramo
temperate Asia.

Presentation Type: Oral Paper:Papers for Topics
Session: 38
Location: Marlborough A/Riverside Hilton
Date: Wednesday, July 31st, 2013
Time: 9:00 AM
Number: 38003
Abstract ID:103
Candidate for Awards:None


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