Journal Article

Minority cytotypes in European populations of the <i>Gymnadenia conopsea</i> complex (Orchidaceae) greatly increase intraspecific and intrapopulation diversity

Pavel Trávníček, Jana Jersáková, Barbora Kubátová, Jana Krejčíková, Richard M. Bateman, Magdalena Lučanová, Eva Krajníková, Tamara Těšitelová, Zuzana Štípková, Jean-Pierre Amardeilh, Emilia Brzosko, Edyta Jermakowicz, Olivier Cabanne, Walter Durka, Peter Efimov, Mikael Hedrén, Carlos E. Hermosilla, Karel Kreutz, Tiiu Kull, Kadri Tali, Olivier Marchand, Manel Rey, Florian P. Schiestl, Vladislav Čurn and Jan Suda

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 110, issue 5, pages 977-986
Published in print October 2012 | ISSN: 0305-7364
Published online October 2012 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcs171
Minority cytotypes in European populations of the Gymnadenia conopsea complex (Orchidaceae) greatly increase intraspecific and intrapopulation diversity

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

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.

Key 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.

Keywords: Coexistence; contact zone; cytogeography; flow cytometry; fragrant orchid; Gymnadenia; Orchidaceae; hybridization; mixed-ploidy population; polyploidy; sympatry; unreduced gametes

Journal Article.  5704 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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