Abstract Detail

Population Genetics

Gaffney, Jessica [1], Galliart, Matt [2], Sabates, Sofia [3], Baer, Sara [4], Maricle, Brian [5], McCrea, Evan [4], Bello, Nora [3], Johnson, Loretta [6].

Variations in polyploidy in Big Bluestem (Andropogon gerardii) ecotypes across the Great Plains.

Although polyploidy is common in prairie grasses, its causes and implications for prairie ecosystems are currently not known.  By studying the occurrence and distribution of polyploids of big bluestem (Andropogon gerardii) across the Great Plains, we aimed to initiate study of the potential roles of polyploidy in changing environments.  Among big bluestem populations, two cytotypes are commonly observed: hexaploids (6X) and enneuploids (9X).  Using flow cytometry to quantify genome size, we were able to determine cytotype of individual plants representing three ecotypes (Illinois, eastern Kansas, and central Kansas), each comprised of four populations, planted reciprocally across a precipitation gradient in Hays, KS, Manhattan, KS, and Carbondale, IL.  Over 300 plants were analyzed for genome size. Although the three ecotypes were morphologically distinct, no significant association between cytotype and plant height was observed at the Manhattan planting site.  Cytotype varied, though only slightly, when the same central Kansas ecotype was compared across different reciprocal garden planting sites. The central Kansas ecotype plants had a smaller mean genome size (LSMean±SEM: 5.26±0.04 pg of DNA) when grown in eastern Kansas, compared to when the same populations were grown in central Kansas (5.58±0.06 pg of DNA). In contrast, the Illinois ecotype showed no evidence for site-specific differences in genome size when planted in Illinois or Manhattan. In certain circumstances, the mean ploidy level was significantly higher for plants grown in natural populations than for those grown in reciprocal garden conditions, notably the Relict Prairie population growing in central Kansas and the Tallgrass Prairie National Park population growing in eastern Kansas. This suggests the presence of long term selection in several native prairie populations for the relatively rare enneuploids, indicating population-specific differences in genome size, even within ecotypes.  These results suggest a growth and maintenance advantage of enneuploids in natural populations that may be absent in restorations.  This advantage of enneuploidy in native field populations might provide clues to big bluestem’s mechanisms of adapting to increasingly dry climates.

1 - University of Colorado, Boulder, CO, 80305, USA
2 - Kanas State University, Division of Biology, Ackert Hall, Manhattan, KS, 66506, United States
3 - Kansas State University, Manhattan, KS, 66506, USA
4 - Southern Illinois University, Carbondale, IL, USA
5 - Fort Hays State University, Department Of Biological Sciences, 600 Park St., Hays, KS, 67601-4099, USA
6 - Kansas State University, Biology, Ackert Hall Rm 232, Manhattan, KS, 66506-4901, USA

Keywords:
polyploidy
big bluestem
cytotype
Prairie
precipitation gradient.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Eyrie/Boise Centre
Date: Monday, July 28th, 2014
Time: 5:30 PM
Number: PPG001
Abstract ID:487
Candidate for Awards:None