Genetic structure of plantations and the conservation of genetic resources of Brazilian pine (Araucaria angustifolia)

With growing concern about maintenance of genetic variation and conservation of gene resources, the question arises on the extent to which a planted population should be considered a resource able to preserve the gene pool of a species. In this study, levels of genetic diversity were assessed in natural and planted populations of Araucaria angustifolia using AFLPs and nuclear microsatellites, in order to assess the usefulness of planted forests in programs of species’ genetic resource conservation. In general, the genetic structure of the plantations was not strongly differentiated from the natural populations. For microsatellites, gene diversity (H) and allelic richness were significantly higher in plantations, while inbreeding was not different between planted and natural populations. For AFLPs, no significant difference was found between groups in the measures of genetic diversity. In the cluster analysis based on microsatellite data, plantations and natural populations from Santa Catarina State were grouped together, suggesting that plantations preserved genetic information very similar to natural populations. The cluster analysis of populations based on AFLP data differentiated plantations from natural populations. This pattern may be a result of genetic hitchhiking of AFLP fragments with genes under selective pressure due to plantations establishment and management. We suggest that the moderate to high level of genetic diversity retained in A. angustifolia populations after the intense fragmentation of the natural forest has the potential to supply plant material with sufficient genetic diversity for the species conservation through the establishment of planted forests. A sustainable management of the extant forest remnants and forestation/reforestation enterprises should additionally attend to trends revealed in previous studies concerning population structure and gene flow.