title: Distribution and diversity of cytotypes in Dianthus broteri as evidenced by genome size variations.
abstract: OBJECTIVE
  Studying the spatial distribution of cytotypes and genome size in plants can provide valuable information about the evolution of polyploid complexes. Here, the spatial distribution of cytological races and the amount of DNA in Dianthus broteri, an Iberian carnation with several ploidy levels, is investigated.
  
  
  METHODS
  Sample chromosome counts and flow cytometry (using propidium iodide) were used to determine overall genome size (2C value) and ploidy level in 244 individuals of 25 populations. Both fresh and dried samples were investigated. Differences in 2C and 1Cx values among ploidy levels within biogeographical provinces were tested using ANOVA. Geographical correlations of genome size were also explored.
  
  
  RESULTS
  Extensive variation in chromosomes numbers (2n = 2x = 30, 2n = 4x = 60, 2n = 6x = 90 and 2n = 12x =180) was detected, and the dodecaploid cytotype is reported for the first time in this genus. As regards cytotype distribution, six populations were diploid, 11 were tetraploid, three were hexaploid and five were dodecaploid. Except for one diploid population containing some triploid plants (2n = 45), the remaining populations showed a single cytotype. Diploids appeared in two disjunct areas (south-east and south-west), and so did tetraploids (although with a considerably wider geographic range). Dehydrated leaf samples provided reliable measurements of DNA content. Genome size varied significantly among some cytotypes, and also extensively within diploid (up to 1.17-fold) and tetraploid (1.22-fold) populations. Nevertheless, variations were not straightforwardly congruent with ecology and geographical distribution.
  
  
  CONCLUSIONS
  Dianthus broteri shows the highest diversity of cytotypes known to date in the genus Dianthus. Moreover, some cytotypes present remarkable internal genome size variation. The evolution of the complex is discussed in terms of autopolyploidy, with primary and secondary contact zones.
authors.affiliation: Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, E-41080 Sevilla, Spain. fbalao@us.es
authors.forename: Francisco
authors.initials: F
authors.lastname: Balao
authors.forename: Ramón
authors.initials: R
authors.lastname: Casimiro-Soriguer
authors.forename: María
authors.initials: M
authors.lastname: Talavera
authors.forename: Javier
authors.initials: J
authors.lastname: Herrera
authors.forename: Salvador
authors.initials: S
authors.lastname: Talavera
mesh_terms: D032461:Chromosomes, Plant / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D029749:Dianthus / Q000235:genetics*; D005434:Flow Cytometry; D014644:Genetic Variation / Q000235:genetics; D018745:Genome, Plant / Q000235:genetics*; D011123:Polyploidy
chemical_list: D018744:DNA, Plant