No Genetic Diversity at Molecular Markers and Strong Phenotypic Plasticity in Populations of Ranunculus nodiflorus, an Endangered Plant Species in France
International audience, Background and Aims: Although conservation biology has long focused on population dynamics and genetics, phenotypic plasticity is likely to play a significant role in population viability. Here, an investigation is made into the relative contribution of genetic diversity and phenotypic plasticity to the phenotypic variation in natural populations of Ranunculus nodiflorus, a rare annual plant inhabiting temporary puddles in the Fontainebleau forest (Paris region, France) and exhibiting metapopulation dynamics. Methods: The genetic diversity and phenotypic plasticity of quantitative traits (morphological and fitness components) were measured in five populations, using a combination of field measurements, common garden experiments and genotyping at microsatellite loci. Key Results: It is shown that populations exhibit almost undetectable genetic diversity at molecular markers, and that the variation in quantitative traits observed among populations is due to a high level of phenotypic plasticity. Despite the lack of genetic diversity, the natural population of R. nodiflorus exhibits large population sizes and does not appear threatened by extinction; this may be attributable to large phenotypic plasticity, enabling the production of numerous seeds under a wide range of environmental conditions. Conclusions: Efficient conservation of the populations can only be based on habitat management, to favour the maintenance of microenvironmental variation and the resulting strong phenotypic plasticity. In contrast, classical actions aiming to improve genetic diversity are useless in the present case.
Auteurs du document :
Noël, Florence, Machon, Nathalie, Porcher, Emmanuelle, Institut des Sciences de l'Evolution de Montpellier (UMR ISEM) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École pratique des hautes études (EPHE) ; Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), Centre d'Ecologie et des Sciences de la COnservation (CESCO) ; Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Conservatoire Botanique National du Bassin Parisien (CBNBP) ; Muséum national d'Histoire naturelle (MNHN)