Genetic temporal dynamics in restored wetlands : A case of a predominantly clonal species, Berula erecta (Huds.) Coville
Résumé
Genetic variability is a key component of biodiversity. Therefore, the health of populations that colonise restored ecosystems depends on maintaining a level of genetic diversity similar to what is found in unre- stored and healthy populations. Wetland restoration occurs frequently, but genetic monitoring rarely considers the genetic variability of species that grow spontaneously in restored ecosystems as a marker of overall ecological restoration success. In this study, the temporal dynamics of genetic variability in an aquatic pioneer plant species, Berula erecta (Hudson) Coville (Apiaceae), were assessed based on an anal- ysis of 12 different microsatellite markers. We hypothesised that vegetative propagation was enhanced by restoration and consequently tended to decrease clonal richness and to stabilise genetic diversity. Several genetic and genotypic indices were surveyed over five years in three restored and two reference sites. An assessment of the breeding system in this population suggested that B. erecta was an ISR (initial seedling recruitment) species; for this type of species, disturbances caused by dewatering permitted an increase in the level of genetic diversity. The results suggested that there were no temporal changes in genetic diversity at any of the studied sites over the time scale of the study, despite strong changes in population sizes that were induced by restoration processes. Clonal richness tended to decrease over time, although not significantly. This study demonstrated that restored populations of clonal species maintained their genetic variability over time and that they might even display greater diversity than unrestored populations. This study also underscored the importance of monitoring the genetic diversity of species in restoration projects to maintain biodiversity.