Straub, Shannon C.K. , Doyle, Jeff J. .
Conservation Genetics of Amorpha georgiana Wilbur (Fabaceae).
Amorpha georgiana (Fabaceae) is a rare shrub native to the southeastern United States. Amorpha georgiana var. georgiana is the more widespread variety of this species and is considered to be endangered (NC) or a species of special concern (SC, GA). Amorpha georgiana var. confusa is restricted to the coastal plain of North Carolina, where it is listed as threatened. The morphological distinctions observed for the two varieties, including differences in leaflet and petiole size, raceme arrangement, petal color, and habitat preference, may warrant recognition of each as a separate species. In order to assess the taxonomy, genetic diversity, and population structure in the two varieties, numerous microsatellite loci were developed. Individuals from nine A. georgiana var. georgiana and six A. georgiana var. confusa populations were genotyped for multiple loci. Population genetics analyses for A. georgiana var. georgiana reveal a high amount of genetic diversity with an average of 14.3 alleles per locus and few significant departures from Hardy-Weinberg expectations. Neither Structure 2.1 analyses nor AMOVA reveal population structuring for this variety with the majority of the genetic variation occurring within populations, which suggests high levels of gene flow among populations. Due to the longevity of these plants, these results may reflect historical gene flow prior to the relatively recent extirpation of most recorded populations of this variety. For A. georgiana var. confusa, genotyping revealed two to four alleles per locus for each individual, suggesting that this variety is tetraploid. The difference in ploidy, combined with the presence of private microsatellite alleles, morphological differences, and non-overlapping geographical distributions support the recognition of each variety as a distinct species. These results will be applicable for future conservation management and planning for in situ, as well as ex situ, conservation efforts.
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1 - Cornell University, L.H. Bailey Hortorium and Department of Plant Biology, 228 Plant Science Building, Ithaca, New York, 14853, USA
Simple Sequence Repeats (SSRs)
Presentation Type: Oral Paper:Papers for Topics
Location: Williford A/Hilton
Date: Tuesday, July 10th, 2007
Time: 8:15 AM