Abstract Detail

Principles of crucifer evolution

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

Easy come, easy go: Diversification and extinction via hybridization in the genus Boechera (Brassicaceae).

In the past few years, the genus Boechera (Brassicaceae) has emerged as a model system for studies of apomixis and ecological genomics. There is, however, one major caveat: to fully exploit the potential of Boechera as a model system, we must deal with the formidable systematic complexity of the genus. Boechera has one of the highest rates of divergent speciation on record; in less than 4 million years, it has produced at least 75 extant, morphologically distinct, sexual diploids. Yet this figure pales in comparison to the number of independent lineages produced by hybridization. Reticulate evolution among geographically proximate sexual diploids has given rise to hundreds of diploid and triploid hybrid lineages that primarily reproduce through apomixis. Recently, great progress has been made toward understanding the complex systematics of Boechera by integrating morphological, ecological, and genetic data. Most significant has been the development of a15-locus microsatellite data set that allows us to determine the genomic make-up, ploidy level and reproductive mode of nearly any Boechera specimen collected within the last 150 years. Analyses of these microsatellite data provide intriguing insights regarding the impact of hybridization on taxon diversity in Boechera. Although there are, indeed, hundreds of hybrid lineages, none of these have been particularly successful in an evolutionary sense. Geographically widespread genomic combinations (such as B. divaricarpa) invariably turn out to be a mosaic of independent origins, each confined to a small portion of the total range. The discovery of orphan genomes (found only in hybrids) and rare species driven to the verge of extinction by hybridization suggests that reticulate evolution may also play a significant role in the extinction of sexual diploids. So far as biodiversity in Boechera is concerned, hybridization clearly is a two-edged sword.

Broader Impacts:

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

Keywords:
apomixis
microsatellites
Systematics
triploidy.

Presentation Type: Symposium or Colloquium Presentation
Session: C4
Location: Delaware C/Hyatt
Date: Tuesday, July 10th, 2012
Time: 2:30 PM
Number: C4005
Abstract ID:802