@article {KNZ001395,
	title = {Genomic and resistance gene homolog diversity of the dominant tallgrass prairie species across the U.S. Great Plains precipitation gradient},
	journal = {PLoS ONE},
	volume = {6:e17641},
	year = {2011},
	abstract = {<p>Background Environmental variables such as moisture availability are often important in determining species prevalence and intraspecific diversity. The population genetic structure of dominant plant species in response to a cline of these variables has rarely been addressed. We evaluated the spatial genetic structure and diversity of Andropogon gerardii populations across the U.S. Great Plains precipitation gradient, ranging from approximately 48 cm/year to 105 cm/year. Methodology/Principal Findings Genomic diversity was evaluated with AFLP markers and diversity of a disease resistance gene homolog was evaluated by PCR-amplification and digestion with restriction enzymes. We determined the degree of spatial genetic structure using Mantel tests. Genomic and resistance gene homolog diversity were evaluated across prairies using Shannon\&$\#$39;s index and by averaging haplotype dissimilarity. Trends in diversity across prairies were determined using linear regression of diversity on average precipitation for each prairie. We identified significant spatial genetic structure, with genomic similarity decreasing as a function of distance between samples. However, our data indicated that genome-wide diversity did not vary consistently across the precipitation gradient. In contrast, we found that disease resistance gene homolog diversity was positively correlated with precipitation. Significance Prairie remnants differ in the genetic resources they maintain. Selection and evolution in this disease resistance homolog is environmentally dependent. Overall, we found that, though this environmental gradient may not predict genomic diversity, individual traits such as disease resistance genes may vary significantly.</p>},
	keywords = {LTER-KNZ, Amplified fragment length polymorphism, Cloning, Hexaploidy, Maize, Plant genomics, Plant pathology, Ploidy, Population genetics},
	doi = {10.1371/journal.pone.0017641},
	url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0017641},
	author = {Rouse, M.N. and Saleh, A.A. and Seck, A. and Keeler, K.H. and Travers, S.E. and Hulbert, S.H. and Garrett, K.A.}
}
@article {KNZ00819,
	title = {Clone size of Andropogon gerardii Vitman (Big Bluestem) at Konza Prairie, Kansas},
	journal = {American Midland Naturalist},
	volume = {147},
	year = {2002},
	pages = {295 -304},
	abstract = {Clone size of plants of Andropogon gerardii from Konza Prairie Biological Station, Manhattan, Kansas was estimated from spatial patterns of genetic variation, using proteins detected by starch gel electrophoresis and DNA content (ploidy) measured by flow cytometry. Unique multi-locus protein banding patterns and differences in ploidy were used to exclude plants as members of the same clone. Individual clones averaged about 2 m in diameter and areas of prairie of 100 m2 were calculated to contain an average of 31.8 genetic individuals.},
	keywords = {LTER-KNZ},
	doi = {10.1674/0003-0031(2002)147[0295:CSOAGV]2.0.CO;2},
	author = {Keeler, K.H. and Williams, C.F. and Vescio, L.S.}
}
@article {KNZ00695,
	title = {Comparison of common cytotypes of Andropogon gerardii (Andropoganeae, Poaceae)},
	journal = {American Journal of Botany},
	volume = {86},
	year = {1999},
	pages = {974 -979},
	keywords = {LTER-KNZ},
	author = {Keeler, K.H. and Davis, G.A.}
}
@article {KNZ00606,
	title = {Evolutionary implications of meiotic chromosome behavior, reproductive biology, and hybridization in 6X and 9X cytotypes of Andropogon gerardii (Poaceae )},
	journal = {American Journal of Botany},
	volume = {84},
	year = {1997},
	pages = {201 -207},
	abstract = {Andropogon gerardii, big bluestem, has 60 and 90 chromosome cytotypes. Meiosis in the hexaploid was shown to be regular, although some secondary associations of bivalents form. Meiosis in the enneaploid (2n = 9z = 90) is irregular, leading to most gametes having unbalanced chromosome complements. Both cytotypes show considerable self-incompatibility. Cytotypes crossed freely, forming a variety of fertile euploids and aneuploids. Indistinguishable exomorphology, intermixing in natural populations, and compatibility suggest that A. gerardii is best understood as a cytotypically complex single species.},
	keywords = {LTER-KNZ},
	url = {http://www.amjbot.org/content/84/2/201.short},
	author = {Norrmann, G.A. and Quarin, C.L. and Keeler, K.H.}
}
@inbook {KNZ00492,
	title = {Population Processes},
	booktitle = {The Changing Prairie},
	year = {1995},
	pages = {82 -99},
	publisher = {Oxford University Press},
	organization = {Oxford University Press},
	address = {Oxford},
	keywords = {LTER-KNZ},
	author = {D.C. Hartnett and Keeler, K.H.},
	editor = {Anthony Joern and Keeler, K.K.}
}
@article {KNZ00366,
	title = {Local polyploid variation in the native prairie grass Andropogon gerardii},
	journal = {American Journal of Botany},
	volume = {79},
	year = {1992},
	pages = {1229 -1232},
	keywords = {LTER-KNZ},
	doi = {http://www.jstor.org/stable/2445049},
	author = {Keeler, K.H.}
}
@article {KNZ00289,
	title = {Distribution of polyploid variation in big bluestem (Andropogon gerardii , Poaceae) across the tallgrass prairie region},
	journal = {Genome},
	volume = {33},
	year = {1990},
	pages = {95 -100},
	keywords = {LTER-KNZ, tallgrass prairie},
	doi = {10.1139/g90-015},
	author = {Keeler, K.H.}
}
@proceedings {KNZ00242,
	title = {Polyploid polymorphism in the prairie grass big bluestem (Andropogon gerardii)},
	year = {1989},
	publisher = {University of Nebraska Press},
	address = {Lincoln, NE},
	abstract = {<p>A suprising number of plant species contain individuals of a variety of levels of polyploidy, so that the species is polymorphic for polyploidy. This paper considers possible general causes for this phenomenon in plants of the Great Plains of North America. First we compared the frequency of intraspecific polyploidy in three major plant families, Poaceae, Asteraceae, and Fabaceae. The majority of grass species (Poaceae) and the minority of composite and legume species (Asteraceae and Fabaceae) are polyploid polymorphic. The frequency of grass species with intraspecific polyploidy suggests shared causatin or at least shared tolerance of this character. Having established that the situation occurs frequently in grasses, we analyzed a single species, big bluestem, Andropogon gerardii, looking for information on the function of polyploid polymorphism. We used flow cytometry to determine amount of nuclear DNA per cell; In big bluestem this correlates with chromosome number. Individuals with 7 pg nuclear DNA had 2N=60 chromosomes, and were therefore hexaploid, since in Andropogon x=10. Most other individuals had approximately 10 pg nuclear DNA and 80 (occasionally 90) chromosomes. Seven-pg DNA individuals were predominatnt everywhere, but the frequency of higher polyploids (10 pg nuclear DNA) went from virtually 0 on the eastern end of the tallgrass prairie region to 40\% at the western end. Within native prairies in the west, the full range of variation existed between sites. A recent origin for polyploid polymorphism is suggested in big bluestem and probably other Great Plains grasses, and the data seem most compatible with a transitional situation, although other explanations cannot be ruled out</p>},
	keywords = {LTER-KNZ},
	author = {Keeler, K.H. and Kwankin, B.},
	editor = {Bragg, T.B. and Stubbendieck, J.}
}
