02634nas a2200277   4500008004100000245014400041210006900185490001300254520174100267653004302008653001202051653001502063653001002078653001902088653002002107653001102127653002402138100001602162700001602178700001302194700001702207700001802224700001802242700001802260856007802278       2011                        eng d00aGenomic and resistance gene homolog diversity of the dominant tallgrass prairie species across the U.S. Great Plains precipitation gradient0 aGenomic and resistance gene homolog diversity of the dominant ta0 v6:e176413 a<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>10aAmplified fragment length polymorphism10aCloning10aHexaploidy10aMaize10aPlant genomics10aPlant pathology10aPloidy10aPopulation genetics1 aRouse, M.N.1 aSaleh, A.A.1 aSeck, A.1 aKeeler, K.H.1 aTravers, S.E.1 aHulbert, S.H.1 aGarrett, K.A.  uhttps://journals.plos.org/plosone/article?id=10.1371/journal.pone.001764103161nas a2200205   4500008004100000245012500041210006900166260004300235300001100278490002100289520245800310653002602768653003102794653002002825653002402845653002102869653001502890100001402905856003602919       2009                        eng d00aHost associated genetic divergence and sexual isolation in the grasshopper Hesperotettix viridis (Orthoptera: Acrididae)0 aHost associated genetic divergence and sexual isolation in the g  aManhattan, KSbKansas State University  a1 -1270 vPhD Dissertation3 a<p>Understanding evolutionary processes that structure genetic variation associated with lineage diversification and speciation is a central problem. Shifts in host plant use by insect herbivores and subsequent divergence in mating signals can lead to sexual isolation, especially when selection for specialization on different hosts restricts gene flow among populations. The grasshopper Hesperotettix viridis (Thomas) is an oligophagous grasshopper feeding on plants primarily in the host plant genera Gutierrezia and Solidago in Kansas. I used mitochondrial and microsatellite genetic markers to evaluate the diversification pattern and underlying evolutionary mechanisms of two putative host races of H. viridis. I also quantified host preferences, the degree of sexual isolation among putative host races and divergence in cuticular attributes to identify the nature and origins of initial barriers that isolated populations in the formative stages of divergence. mtDNA data revealed a star-shaped phylogeny, suggesting isolation in a single refugium ~110,000 years ago based on a molecular clock, followed by rapid population expansion. Microsatellite data reveal significant host-based genetic differentiation and structuring in H. viridis populations in Kansas, including a microsatellite locus under strong divergent selection. Neutral microsatellite loci did not reveal a differentiation pattern specific to host plant use. Significant host-based preferences by individuals that fed on two host plant groups were detected in host paired-feeding preference studies. No-choice mate selection experiments revealed preferences for individuals collected from the same host species independent of location with little mating observed between individuals from different host species. Significant differentiation in color and cuticular composition among different host plant races within the study area was also detected. Correlations between host choice, mate choice and phenotypic divergence were observed and this host associated divergence appears to have a genetic basis. Based on the results of this study, I conclude that divergent selection for host plant use underlies observed sexual isolation among populations in this species. Hesperotettix viridis populations in Kansas that fed on Solidago and Gutierrezia species represent two incipient host races, early stages of diversification that could lead to speciation in insect herbivores.</p>10aHesperotettix viridis10aHost Associated Divergence10aMicrosatellites10aPopulation genetics10asexual isolation10aSpeciation1 aGrace, T.  uhttp://hdl.handle.net/2097/1541