Allphin, Loreen , Beck, James , Windham, Michael .
Microsatellites provide new insights into the origin and distribution of Duchesne rock-cress (Boechera duchesnensis: Brassicaceae).
Microsatellites (also known as simple sequence repeats) are DNA markers that are becoming increasingly popular for population-level genetic studies. Because of their substantial variability and co-dominant inheritance, they also provide a powerful tool for investigating hybrid origins. In a separate talk, we have demonstrated that a number of microsatellite loci are amplifiable and informative across the 70+ sexual diploid species belonging to the taxonomically complex genus Boechera (formerly part of Arabis). In this presentation, we use microsatellite data, in conjunction with morphology, isozymes and chromosome counts, to investigate the origin(s) and taxonomic status of Boechera duchesnensis (formerly called Arabis pulchra var. duchesnensis) a rare endemic of northern Utah. Our results indicate that collections of this taxon from the type locality are diploid hybrids between B. formosa and B. thompsonii, two well-differentiated sexual diploids that co-occur at this site. At least two independent hybridization events were involved, and there is evidence that one of the resultant genotypes may be reproducing by apomixis. Widely disjunct populations from the Four Corners region occasionally identified as B. duchesnensis represent an entirely different hybrid. Microsatellite data indicate that this unnamed taxon is a trigenomic triploid incorporating genomes from B. formosa, B. perennans, and a newly discovered sexual diploid B. kelseyana. True B. duchesnensis is a very narrow endemic, apparently restricted to the immediate vicinity of the type locality. This study illustrates, once again, that conservation of rare species is critically dependent on our understanding of their taxonomic relationships.
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1 - Brigham Young University, Department of Plant and Wildlife Sciences, 275 Widtsoe Building, Provo, UT, 84602, USA
2 - Duke University, Department of Biology, 139 Biological Sciences Building, PO Box 90338, Durham, North Carolina, 27708, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 556B/Convention Center
Date: Wednesday, August 4th, 2010
Time: 1:15 PM