title: Ecogeography of ploidy variation in cultivated potato (Solanum sect. Petota).
abstract: OBJECTIVE
  The taxonomy of cultivated potatoes has been highly controversial, with estimates of species numbers ranging from 3 to 17. Ploidy level has been one of the most important taxonomic characters to recognize cultivated potato species, containing diploid (2n = 2x = 24), triploid (2n = 3x = 36), tetraploid (2n = 4x = 48), and pentaploid (2n = 5x = 60) cultivars. We tested the environmental associations of different ploidy levels in cultivated potato species that traditionally have been recognized as Linnaean taxa to see whether, in combination with prior morphological, molecular, and crossing data, some of the ploidy variants can be recognized as distinct taxa. •
  
  
  METHODS
  We summarize 2780 chromosome counts of landrace cultivated potatoes, provide georeferences to 2048 of them, and analyze these data for 20 environmental variables at 10-min resolution using the randomForest algorithm to explore associations with taxa and ploidy variants. •
  
  
  RESULTS
  Except for the S. tuberosum Chilotanum Group and extreme northern and southern range extensions of the Andigenum Group, it is impossible to find distinct habitats for the ploidy variants of the S. tuberosum Andigenum Group. •
  
  
  CONCLUSIONS
  Our distributional and ecological data, in combination with prior results from morphology, microsatellites, and crossing data, provide yet additional data to support a major reclassification of cultivated potato species. A rational, stable, and universally accepted taxonomy of this major crop plant will greatly aid all users of wild and cultivated potatoes from breeders to gene bank managers to ecologists and evolutionary biologists.
authors: USDA, Agricultural Research Service, Department of Horticulture, University of Wisconsin, 1575 Linden Drive, Madison, Wisconsin 53706-1590 USA.
authors: David M
authors: DM
authors: Spooner
authors: Tatjana
authors: T
authors: Gavrilenko
authors: Shelley H
authors: SH
authors: Jansky
authors: A
authors: A
authors: Ovchinnikova
authors: E
authors: E
authors: Krylova
authors: Sandra
authors: S
authors: Knapp
authors: Reinhard
authors: R
authors: Simon