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

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 pictur

Atlas des Orchidées de France

Conclusion du long travail d’inventaire des stations d’orchidées de France, cet ouvrage fondamental de 400 pages, au format A4, présente, à travers 159 monographies superbement illustrées de 380 photographies et 154 cartes, un état des lieux de la répartition de ces plantes fascinantes. Cet Atlas est une Publication scientifique du Muséum national d’Histoire naturelle (MNHN), en coédition avec l’éditeur Biotope. Quatorze auteurs et de nombreux photographes ont mené à bien cette entreprise ; François Dusak et Daniel Prat, de la SFO, étant les coordinateurs de cette équipe. Commandé par le Ministère chargé de l’environnement, l’inventaire, fruit du travail de plus de 3 000 observateurs ou organismes (dont les Conservatoires botaniques nationaux), regroupe, sur deux décennies, plus de 420 000 données transmises par la SFO au MNHN (Service du patrimoine naturel) en 2008. Les parties introductives de l’ouvrage détaillent la genèse de la cartographie, les implications de cet Atlas sur la gestion des populations d’orchidées, les différentes zones biogéographiques déduites de leur répartition et des données climatiques, et font le point sur les risques auxquels elles sont exposées. Pour chaque taxon, sont indiqués en plus d’une carte détaillée, la répartition globale, l’écologie et le classement liste rouge nationale selon les critères de l’Union Internationale pour la Conservation de la Nature (UICN). L’Atlas procure des informations de référence pour définir les priorités de protection et les actions à mener en faveur des espèces classées en danger (EN) ou vulnérables (VU) telles que le Sabot de Vénus plante spectaculaire, le Liparis de Loesel espèce fragile des milieux humides, et l’Ophrys de l’Aveyron qui occupe une aire très restreinte. Ce dernier est une des rares espèces de la flore française proposée pour inscription sur la liste rouge mondiale de l’UICN. Dans la lignée des ouvrages naturalistes édités récemment par Biotope et le MNHN, cet Atlas offre un outil important pour l’évaluation de la biodiversité française. Il permet de mieux appréhender les difficultés de la conservation de nos orchidées et de leurs habitats et de comprendre les menaces qui pèsent sur elles ; de ce fait il est, pour les nombreux passionnés, un complément indispensable des livres existants axés sur l’identification. Enfin, la répartition des orchidées, servira tous ceux qui interviennent dans la gestion du territoire

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

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