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Abstract Detail


Principles of crucifer evolution

Alexander, Patrick [1], Beck, James [2], Li, Fay-Wei [3], Windham, Michael [4], Allphin, Loreen [5], Al-Shehbaz, Ihsan A.  [6], Bailey, Donovan [7].

Patterns of Evolutionary Divergence and Homoploid Hybridization in Boechera (Brassicaceae).

Boechera, with its primary center of distribution in western North America, is one of the diverse genera of Brassicaceae. The genus includes a wide range of sexual diploids, apomictic di- and tri-genomic triploids, and numerous recently discovered apomictic diploid hybrid lineages (hereafter - apomictic diploids). This lineage diversity offers a unique opportunity to investigate correlations between parental divergence and the establishment of new hybrid lineages. Nearly 100 years ago, Winge noticed correlations between parental divergence and the establishment of polyploid lineages. Subsequent studies have discussed a positive correlation between parental divergence and the likely establishment of a novel polyploid species, ultimately suggesting that increased divergence of parental genomes favors, and perhaps even drives, polyploid lineage formation. More recent research on parental divergence and hybridization has extended to homoploid hybrids, where a negative correlation between parental divergence and successful hybrid lineage establishment is clear. In both cases, the primary explanation for these patterns involves potential problems with meiotic pairing and segregation (i.e., diploid hybrids require homeologous pairing for even segregation while homeologous pairing in polyploids actually contributes to uneven segregation). To determine the general applicability of this model, we investigate the correlation between parental divergence and the establishment of apomictic diploid hybrid lineages in Boechera. Phylogenetic hypotheses were generated for most of the sexual diploid species in the genus based on sequence data from nrDNA ITS and seven low-copy nuclear genes. The parentages of apomictic diploid hybrids were inferred based on 15 microsatellite loci representing nearly every linkage group in the genome. Because seed production in these lineages does not involve meiosis, lineage establishment should not be constrained by parental divergence.

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1 - New Mexico State University, Biology Department, 248 Foster Hall, MSC 3AF, Las Cruces, NM, 88003, USA
2 - Wichita State University, Biology, 1845 Fairmount, Box 26, Wichita, KS, 67260-0026, USA
3 - Duke University, Biology, Box 90338, Durham, NC, 27708, USA
4 - DUKE UNIVERSITY, Department Of Biology, BOX 90338, DURHAM, NC, 27708, USA
5 - Brigham Young University, DEPT INTEGRATIVE BIOLOGY, 275 WIDB, Provo, UT, 84602, USA
6 - Missouri Botanical Garden, Asian Botany, P.O. Box 299, St. Louis, MO , MO, 63166-0299, USA
7 - New Mexico State University, Department Of Plant Sciences, P.O. Box 30001 Msc 3AF, Las Cruces, NM, 88003, USA

Keywords:
Brassicaceae
Boechera
homoploid
hybridization
Polyploidy
apomixis.

Presentation Type: Symposium or Colloquium Presentation
Session: C4
Location: Delaware C/Hyatt
Date: Tuesday, July 10th, 2012
Time: 2:45 PM
Number: C4006
Abstract ID:764


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