Rajanikanth, G , Hughes, Colin E. , Filer, Denis L. , Bailey, C. Donovan .
Three independent allopolyploidization events involving divergent crosses with one widespread diploid in Leucaena.
The genus Leucaena comprises a complex assemblage of 17 diploid and five polyploid species whose evolutionary relationships have been complicated by human translocation, interspecific hybridization, and polyploid speciation. Despite previous study, the origin(s) of several of the polyploid taxa, as either autoploids or alloploids, has remained uncertain. Using a multilocus gene-tree approach incorporating data from four cpDNA markers and seven nuclear encoded loci, we have identified strong support for the genomic contributors in each polyploid. All five polyploid species retain divergent genomic backgrounds at multiple loci consistent with allopolyploidy and four of the five polyploids have the geographically widespread diploid L. trichandra, or a “trichandra-like” ancestor, in their genomes. The L. trichandra genome appears to have combined with three divergent diploid species in the formation of the tetraploids L. confertiflora, L. diversifolia, and the species pair L.pallida plus L. involucrata. The later pair share the same maternal-paternal genomic combination, questioning whether their allopolyploid genomes are the result of independent allopolyploid speciation events or secondary divergent speciation from one allopolyploid ancestor.
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1 - New Mexico State University, Department of Biology, Po Box 30001, Department 3Af, Las Cruces, New Mexico, 88003-8001, USA
2 - University of Zurich, Institute of Systematic Botany, Zollikerstrasse 107, Zurich, ZH, 8008, Switzerland
3 - Oxford University, Plant Sciences, Oxford, OX1 3RB, UK
Presentation Type: Oral Paper:Papers for Sections
Location: Ballroom D/Convention Center
Date: Monday, August 2nd, 2010
Time: 3:00 PM