Evolution of genetic diversity in metapopulations: Arabidopsis thaliana as an experimental model

Claire Lavigne, Xavier Reboud, Madeleine Lefranc, Emmanuelle Porcher, Fabrice Roux, Isabelle Olivieri, Bernard Godelle
2001 Genetics Selection Evolution  
Two experiments were set up to investigate how to maintain or create genetic diversity in artificial or managed populations of plants. Using Ambidopsis thaliana, we established 18 metapopulations of 20 populations each, all with the same initial genetic composition. We tested the effects of the population size, the artificial selection regime and the extinction/recolonisation regime. We report the results of the first four generations of evolution for a trait under selection (precocity) and for
more » ... (precocity) and for allozyme diversity. As expected, overall diversity decreased in each metapopulation, and differentiation among populations increased. As expected, the differentiation was weaker for larger population sizes and in the treatment with extinction and recolonisat ion with no bottleneck. Artificial selection was effective because the life cycle duration was much reduced. However, most of the reduction occurred during the first generation. We observed an increase of one allele at the LAP-2 locus in all metapopulations, breaching neutral assumptions for this locus. Finally, the selection regime made little difference for small population sizes, whereas large metapopulations were more differentiated when artificial selection was heterogeneous among populations. Altogether, our results agree with theoretical expectations, and provide some new results, which could not have been anticipated. In particular, the overall decrease in genetic diversity was very large (of the order of 20% in 4 generations) even for metapopulations of 2000 individuals. genetic diversity / experimental evolution / conservation / small populations / precocity S400 C. Lavigne et al. Resume -Evolution de la diversite genetique en metapopulation : A rabidopsis thaliana comme modele experimental. Deux experimentations, visant it etudier comment maintenir ou creer de la diversite dans les populations artificielles ou gerees de plantes, ont ete menees en utilisant Ambidopsis thaliana comme espece modele. Nous avons cree 18 metapopulations de 20 populations de meme composition initiale. Nous avons teste les effets de la taille des populations, du regime de selection et du regime d'extinction/recolonisation. Les resultats sur l'evolution du caractere selectionne (duree du cycle de vie) et sur la diversite enzymatique sont presentes pour les quatre premieres generations. Conformement aux attendus theoriques, la diversite a globalement diminue dans les metapopulations et les populations se sont differenciees. La differenciation est plus faible pour les grandes populations et dans le traitement avec extinctions et recolonisations sur une base genetique large. La selection artificielle a reduit la duree du cycle des plantes. Cette reduction a essentiellement eu lieu pendant la premiere generation. Nous avons observe une augmentation d'un des alleles au locus LAP-2 dans toutes les metapopulations, en contradiction avec la neutralite presupposee de ce locus. Enfin, la selection a eu peu d'effet dans les petites populations alors que les grandes populations sont plus differenciees pour les allozymes quand la selection est heterogene entre populations. Globalement, nos resultats sont plutot en accord avec les predictions theoriques ; certains resultats sont neanmoins inattendus. En particulier, la perte de diversite globale a ete tres imp ortante (de l'ordre de 20 % en quatre generations), meme dans les metapopulations de 2000 individus. diversite genetique / evolution experimentale / conservation / petites populations / precocite
doi:10.1186/bf03500892 fatcat:nskpqrfotrghlhcfjowwai3eba