Arias, Tatiana , Pires, Joseph .
A fully resolved phylogeny of the brassica crops and wild relatives (Brassiceae: Brassicaceae): testing biogeographical and diversification hypothesis in the tribe.
We reconstructed the phylogeny of the tribe Brassiceae (Brassicaceae) using four plastid regions (rpl32-trnL, atpI-atpH, psbD-trnT, Ycf6-PsbM) in order to understand historical biogeography, chronological origin of the major lineages in the tribe and variation in diversification rates in the phylogeny. We sampled representatives of almost all genera in the tribe covering the entire natural range for the tribe from Central Asia to western Mediterranean. New collections from fieldwork in the Mediterranean as well as old material from herbaria were included. Phylogenetic analysis recovered for the first time eight well-supported clades in the tribe including a new African clade comprised of genera that have not been previously sampled (Henophyton). Relationships within and between there eight major clades are also strongly supported. We estimated the tribe origin and as such the triplication event to be ca.37.54 Mya during the Eocene- Oligocene boundary in the Saharo-Sindian region. Main clades in the tribe appeared in the boundary between the Paleogene and Neogene, while the majority of species diversified during the Miocene (20 - 10 Mya). Core Brassiceae had a SW Mediterranean origin around 28.24 Mya. Time estimates are older than previously hypothesized indicating that the evolution of the tribe ocurred much more slowly. We concluded that ancestors of the domesticated species in the Oleracea clade originated in the NE Mediterranean region late in the Miocene (8.73Mya.). Brassica rapa ancestors were then dispersed to the Iranio-Turanian region and Asia around 3.23 Mya (Pliocene), while immediate ancestors of the cole crops were dispersed to the Euro-Siberian region around2.39 Mya (Pleistocene). A strong shift in diversification rates was only found in the Nigra clade.Broader impacts: Results from this study will have significant potential for understanding these economically vital crops and their diversity. These studies will do so by first promoting the understanding of the evolutionary relationships among species in the tribe. The proposed methods are of most interest to evolutionary biologists since they offer new and inexpensive ways to sequence, and the capacity to analyze, many unlinked loci. We are developing an online resource that will make all resources generated in this project available to the scientific community. We are training undergraduate students.
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1 - University of Missouri, Biological Sciences, 311 Life Sciences Center, Columbia, MO, 65211, USA
2 - University Of Missouri, 371 Bond Life Sciences Center, 1201 Rollins Street, Columbia, MO, 65211-7310, USA
Presentation Type: Poster:Posters for Topics
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM