title: Minority cytotypes in European populations of the Gymnadenia conopsea complex (Orchidaceae) greatly increase intraspecific and intrapopulation diversity.
abstract: OBJECTIVE
  Patterns of ploidy variation among and within populations can provide valuable insights into the evolutionary mechanisms shaping the dynamics of plant systems showing ploidy diversity. Whereas data on majority ploidies are, by definition, often sufficiently extensive, much less is known about the incidence and evolutionary role of minority cytotypes.
  
  
  METHODS
  Ploidy and proportions of endoreplicated genome were determined using DAPI (4',6-diamidino-2-phenylindole) flow cytometry in 6150 Gymnadenia plants (fragrant orchids) collected from 141 populations in 17 European countries. All widely recognized European species, and several taxa of less certain taxonomic status were sampled within Gymnadenia conopsea sensu lato.
  
  
  RESULTS
  Most Gymnadenia populations were taxonomically and/or ploidy heterogeneous. Two majority (2x and 4x) and three minority (3x, 5x and 6x) cytotypes were identified. Evolution largely proceeded at the diploid level, whereas tetraploids were much more geographically and taxonomically restricted. Although minority ploidies constituted <2 % of the individuals sampled, they were found in 35 % of populations across the entire area investigated. The amount of nuclear DNA, together with the level of progressively partial endoreplication, separated all Gymnadenia species currently widely recognized in Europe.
  
  
  CONCLUSIONS
  Despite their low frequency, minority cytotypes substantially increase intraspecific and intrapopulation ploidy diversity estimates for fragrant orchids. The cytogenetic structure of Gymnadenia populations is remarkably dynamic and shaped by multiple evolutionary mechanisms, including both the ongoing production of unreduced gametes and heteroploid hybridization. Overall, it is likely that the level of ploidy heterogeneity experienced by most plant species/populations is currently underestimated; intensive sampling is necessary to obtain a holistic picture.
authors.affiliation: Department of Botany, Charles University in Prague, Prague, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Trávnícek
authors.forename: Jana
authors.initials: J
authors.lastname: Jersáková
authors.forename: Barbora
authors.initials: B
authors.lastname: Kubátová
authors.forename: Jana
authors.initials: J
authors.lastname: Krejcíková
authors.forename: Richard M
authors.initials: RM
authors.lastname: Bateman
authors.forename: Magdalena
authors.initials: M
authors.lastname: Lucanová
authors.forename: Eva
authors.initials: E
authors.lastname: Krajníková
authors.forename: Tamara
authors.initials: T
authors.lastname: Tesitelová
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Stípková
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Amardeilh
authors.forename: Emilia
authors.initials: E
authors.lastname: Brzosko
authors.forename: Edyta
authors.initials: E
authors.lastname: Jermakowicz
authors.forename: Olivier
authors.initials: O
authors.lastname: Cabanne
authors.forename: Walter
authors.initials: W
authors.lastname: Durka
authors.forename: Peter
authors.initials: P
authors.lastname: Efimov
authors.forename: Mikael
authors.initials: M
authors.lastname: Hedrén
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Hermosilla
authors.forename: Karel
authors.initials: K
authors.lastname: Kreutz
authors.forename: Tiiu
authors.initials: T
authors.lastname: Kull
authors.forename: Kadri
authors.initials: K
authors.lastname: Tali
authors.forename: Olivier
authors.initials: O
authors.lastname: Marchand
authors.forename: Manel
authors.initials: M
authors.lastname: Rey
authors.forename: Florian P
authors.initials: FP
authors.lastname: Schiestl
authors.forename: Vladislav
authors.initials: V
authors.lastname: Curn
authors.forename: Jan
authors.initials: J
authors.lastname: Suda
mesh_terms: D005075:Biological Evolution; D032461:Chromosomes, Plant / Q000235:genetics; D003582:Cytogenetics; D062951:Endoreduplication; D005060:Europe; D005434:Flow Cytometry; D014644:Genetic Variation; D018745:Genome, Plant / Q000235:genetics*; D005843:Geography; D006824:Hybridization, Genetic; D029595:Orchidaceae / Q000145:classification / Q000166:cytology / Q000235:genetics*; D011123:Polyploidy