Molecular Ecology and Evolution
Gray, Miranda , St. Amand, Paul , Johnson, Loretta , Akhunov, Eduard , Garrett, Karen , Knapp, Mary , Morgan, Ted , Bai, Guihua .
Genetic Differentiation of Andropogon gerardii (Big Bluestem) Ecotypes Occurring Along a Natural Precipitation Gradient.
Andropogon gerardii (big bluestem) is a wind-dispersed, outcrossing tallgrass that has precipitation-dependent productivity. With its wide distribution across a natural precipitation gradient (400-1200 mm yr-1 from Kansas to Illinois), we expect genetic variation in drought tolerance and potentially, local adaptation. Future climate predictions for big bluestem’s native range include increased periods of drought, making genetic diversity levels critical for predicting this species’ ability to adjust or adapt. We investigated the genetic diversity of 11 total source populations from across 3 prairie ecoregions (Manhattan, Kansas; Hays, KS; Carbondale, Illinois). We also seeded all populations in a large-scale reciprocal garden experiment across the precipitation gradient to test for local adaptation. Across ~400 plants analyzed, 387 neutral genetic markers were identified using two AFLP primer pairs. Several lines of evidence (neighbor-joining trees, STRUCTURE, AMOVA) support genetic differentiation and population structuring of ecotypes. Principal-coordinate analysis shows that 47% of the variation in the first eigenvalue is explainable by mean annual precipitation alone. Interestingly, 11 ecotype-specific loci under diversifying selection were also identified using BayeScan. In spite of the genetic differentiation of Kansas and Illinois ecotypes, AMOVA analyses partition the greatest genetic variation within populations (80%). This high, within-population genetic diversity may allow bluestem populations to better withstand diverse environmental change and thus has implications for prairie restoration and conservation.
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1 - Kansas State University , Plant Pathology, 4024 Throckmorton Plant Sciences Center Claflin Road, Manhattan, KS, 66502, USA
2 - United States Department of Agriculture Agricultural Research Service, Hard Winter Wheat Genetics Research Unit, 4024 Throckmorton Plant Sciences Center Claflin Road, Manhattan, KS, 66502, United States
3 - Kansas State University, Biology, Ackert Hall Rm 232, Manhattan, KS, 66506-4901, USA
4 - Kansas State University , Department of Plant Pathology, 4024 Throckmorton Plant Sciences Center Claflin Road, Manhattan, KS, 66502, United States
5 - Kansas State University , Department of Agronomy, 1709 Throckmorton Plant Sciences Center, Claflin Road, Manhattan, Kansas, 66502, United States
6 - Kansas State University , Department of Biology, 116 Ackert Hall, Claflin Road, Manhattan, Kansas, 66502, United States
Presentation Type: Oral Paper:Papers for Topics
Location: Union B/Hyatt
Date: Monday, July 9th, 2012
Time: 2:15 PM