Geographic pattern of genetic variation in the European globeflower Trollius europaeus L. (Ranunculaceae) inferred from amplified fragment length polymorphism markers

• Main Authors: Despres, L., Loriot, S., Gaudeul, M.
• Other Authors: Laboratoire d'Ecologie Alpine (LECA), Université Joseph Fourier - Grenoble 1 (UJF)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2002
• Subjects: amplified fragment length polymorphism markers (AFLP); genetic; variation; habitat fragmentation; population differentiation; postglacial recolonization; sympatric speciation; Trollius europaeus; Pollinators chiastocheta flies; seed-parasitic pollinators; spruce; picea-abies; population-size; diversity; plant; phylogeography; speciation; evolution; envir; psy; Arctic; Fennoscandia; Fennoscandian
• Online Access: https://hal.archives-ouvertes.fr/halsde-00295037

International audience The distribution of genetic variation and the phylogenetic relationships between 18 populations of the arctic-alpine plant Trollius europaeus were analysed in three main regions (Alps, Pyrenees and Fennoscandia) by using dominant AFLP markers. Analysis of molecular variance revealed that most of the genetic variability was found within populations (64%), although variation among regions (17%) and among populations within regions (19%) was highly significant (P < 0.001). Accordingly, the global fixation index F-ST averaged over loci was high (0.39). The among-population differentiation indicates restricted gene flow, congruent with limited dispersal of specific globeflower's pollinating flies (Chiastocheta spp.). Within-population diversity levels were significantly higher in the Alps (mean Nei's expected heterozygosity H-E = 0.229) than in the Pyrenees (H-E = 0.197) or in Fennoscandia (H-E = 0.158). This finding is congruent with the species-richness of the associated flies, which is maximum in the Alps. We discuss the processes involved in shaping observed patterns of genetic diversity within and among T. europaeus populations. Genetic drift is the major factor acting on the small Pyrenean populations at the southern edge of T. europaeus distribution, while large Fennoscandian populations result probably from a founder effect followed by demographic expansion. The Alpine populations represent moderately fragmented relics of large southern ancestral populations. The patterns of genetic variability observed in the host plant support the hypothesis of sympatric speciation in associated flies, rather than recurrent allopatric speciations.