Population Structure of a Federally Endangered Plant (Astragalus Jaegerianus Munz Fabaceae) With a Limited Range Using Microsatellites

Event Center BC

Astragalus jaegerianus Munz is a federal critically endangered endemic plant species found in a geographically restricted area, with a population size of approximately 5,700 plants as of a 2001 census. A. jaegerianus can be found in the transition zone between 3,100-4,200 feet elevation with a restricted range of 300km2, but have been found to only occupy approximately 85km2 within that range. (Walker & Metcalf, 2008) Endangered species within a restricted geographic range tend toward limited genetic diversity but previous work by Walker & Metcalf (2008) utilized Amplified Fragment Length Polymorphism (AFLP) markers to successfully establish the presence of high levels of genetic variation within and among A. jaegerianus populations. The limitations of AFLP markers are the inability to indicate genome sequence variation. Microsatellite analysis, through the identification of highly conserved regions of genome flanking base pair tandem repeats between 75-300 base pair lengths is another avenue for research which will allow us to determine population structure within this endangered species. The process of microsatellite analysis identifies short tandem base pair repeats, two to four base pairs that are repeated for a total length between 75-300 base pairs from the genome. Through the assistance of Savannah River Ecology Lab, 26 microsatellite loci were identified (Manuscript in process) and from those loci nine optimal loci will be identified for further research on 186 distinct plant samples from 4 different subpopulations.