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Abstract Detail

Conservation Biology

Morris, Ashley B. [1], Trostel, Kevin [1], Scalf, Cassandra [2], Burleyson, Austin [1], Albrecht, Matthew [3].

Genetic variation, demographic structure, and reproductive ecology of the federally endangered Astragalus bibullatus (Fabaceae).

Conservation efforts in rare plant species are increasingly informed by genetic data, but these data are potentially most useful when integrated with long-term demographic studies, particularly in long-lived perennials. In extremely rare taxa with limited numbers of extant populations and apparently low levels of genetic diversity, demographic data have the potential to reveal genetic structure that is otherwise masked in standard population genetic analyses. Astragalus bibullatus is a federally endangered legume endemic to the limestone glades of the Central Basin of Tennessee. Most natural populations occur within a five-mile radius of one another. Molecular studies have suggested limited genetic structure that is not consistent with geographic structure, and long-term demographic data have indicated that reproductive success is dependent on microsite variation in canopy cover. In the present work, we used novel nuclear microsatellite loci to genotype permanently tagged individuals in an ongoing long-term demographic study to further inform reproductive ecology in this system. Seven nuclear loci were used to genotype 302 individuals from five naturally occurring populations and three reintroduction populations in Rutherford County, Tennessee. Population pairwise FST values across all populations ranged from 0.007 to 0.056, with reintroduced populations being more similar to each other and known source populations, as expected (pairwise FST = 0.010 – 0.033). PCoA results suggest high levels of admixture across populations. Structure analysis revealed three possible clusters, although probability of individual assignment to one of these clusters was often less than 0.85. These combined results lead us to conclude that genetic drift has played a significant role in these geographically close, but somewhat reproductively isolated populations. Future analyses will include assessment of correlation between measures of genetic diversity by population (number of effective alleles, expected and observed heterozygosity, and inbreeding coefficient) and measures of individual plant fitness by population (number of flowers per plant, number of fruits per plant) using linear regression. By integrating genetic data and measures of individual fitness within and among populations, we expect to obtain a more sophisticated view of the factors impacting reproductive success and long-term viability in this extremely rare species.

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Related Links:
Morris Lab Website

1 - Middle Tennessee State University, 1301 E. Main Street, SCI 2044, Murfreesboro, TN, 37132, United States
2 - Western Kentucky University, Department of Biology, 1906 College Heights Blvd., Bowling Green, KY, 42101, USA
3 - Missouri Botanical Garden, P.O. Box 299, St. Louis, MO, 63166, USA

cedar glades.

Presentation Type: Oral Paper
Session: 38, Conservation Biology
Location: Sundance 1/Omni Hotel
Date: Wednesday, June 28th, 2017
Time: 2:00 PM
Number: 38003
Abstract ID:473
Candidate for Awards:None

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