title: Environmental correlates of cytotype distribution in Andropogon gerardii (Poaceae).
abstract: •
  
  
  OBJECTIVE
  Information about geographic distribution of cytotypes can provide insight into the origin and maintenance of autopolyploid complexes and builds a foundation for understanding cytotype differentiation and the dynamics of mixed-ploidy populations. Here, we investigate environmental correlates of the geographic distributions of 6x and 9x individuals in the ecologically dominant grass Andropogon gerardii to examine the role of climate in shaping patterns of cytotype distribution in this species.•
  
  
  METHODS
  Flow cytometry was used to estimate ploidy level in 352 individuals from 32 populations across North America. Ecological differentiation of cytotypes was tested by relating BIOCLIM variables to cytotype distribution using principal components analysis and partial linear regression.•
  
  
  RESULTS
  Broad geographic sampling confirmed two primary cytotypes-6x (hexaploid) and 9x (enneaploid)-and revealed that 9x plants are more common than previously thought. Enneaploids occur frequently in the southern portions of the range, with hexaploids dominating in northern regions. Mixed-ploidy populations were common (46.9%). Principal components analysis and partial linear regression indicated that reduced summer precipitation and increased variation in diurnal and seasonal temperature range were significant predictors of the frequency of 9x plants in a population.•
  
  
  CONCLUSIONS
  Results indicate that (1) geographic distribution of 6x and 9x individuals is nonrandom; (2) environmental variables are associated with cytotype distribution in A. gerardii; and (3) nearly half of populations surveyed include both 6x and 9x individuals. The persistence of mixed-ploidy populations may reflect a combination of recurrent polyploid formation and the prevalence of clonal reproduction.
authors.affiliation: Principia College, Department of Biology and Natural Resources, Elsah, Illinois 62028 USA Saint Louis University, Department of Biology, 3507 Macelwane Hall, St. Louis, Missouri 63103 USA.
authors.forename: Christine
authors.initials: C
authors.lastname: McAllister
authors.affiliation: Southern Illinois University, Edwardsville, 1 Hairpin Drive, Edwardsville, Illinois 62025 USA.
authors.forename: Russell
authors.initials: R
authors.lastname: Blaine
authors.affiliation: University of Guelph, Department of Integrative Biology, 50 Stone Road East, Guelph, Ontario, Canada, NIG 2W1.
authors.forename: Paul
authors.initials: P
authors.lastname: Kron
authors.affiliation: Principia College, Department of Biology and Natural Resources, Elsah, Illinois 62028 USA.
authors.forename: Brent
authors.initials: B
authors.lastname: Bennett
authors.affiliation: Principia College, Department of Biology and Natural Resources, Elsah, Illinois 62028 USA.
authors.forename: Heidi
authors.initials: H
authors.lastname: Garrett
authors.affiliation: Principia College, Department of Biology and Natural Resources, Elsah, Illinois 62028 USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Kidson
authors.affiliation: Principia College, Department of Biology and Natural Resources, Elsah, Illinois 62028 USA.
authors.forename: Blanda
authors.initials: B
authors.lastname: Matzenbacher
authors.affiliation: Principia College, Department of Biology and Natural Resources, Elsah, Illinois 62028 USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Glotzbach
authors.affiliation: Saint Louis University, Department of Biology, 3507 Macelwane Hall, St. Louis, Missouri 63103 USA.
authors.forename: Allison J
authors.initials: AJ
authors.lastname: Miller
mesh_terms: D031722:Andropogon / Q000235:genetics*; D002980:Climate; D004777:Environment; D014644:Genetic Variation; D011123:Polyploidy; D014481:United States
keywords: Andropogon gerardii; Poaceae; autopolyploid; cytogeography; cytotype distribution; polyploidy; tallgrass prairie; whole genome duplication