CONICET | Buscador de Institutos y Recursos Humanos

Natural populations of forest tree species from fragmented biomes such as Seasonally Dry Tropical Forests (SDTF) show spatial patterns of genetic variation, which result of demographic and microevolutionary dynamics in the space?time context. Under isolation by distance, kinship levels between individuals are inversely correlated with the spatial distance separating them. Fine-scale spatial genetic structure (FSGS) is defined by the non-random spatial distribution of genotypes, which is generally associated with local family structures as a consequence of restricted gene dispersal. Fragmented landscapes from southern Misiones provide a framework that allows to develop FSGS studies of the native forest tree species Anadenanthera colubrina var. cebil (Leguminosae). The main aim of this work was to evaluate the spatial genetic structure in a remnant population of A. colubrina var. cebil from southern Misiones. As a starting point for spatial inference, a total of 119 individuals of two life stages: adults and saplings were genotyped using eight specific nuclear microsatellite loci for characterizing the genetic diversity of that remnant population. Differences of genetic clusters and FSGS between stages were evaluated. High levels of genetic diversity and high inbreeding were detected. Genetic structure was stronger in saplings than in adult trees, probably due to assortative mating and density dependent mortality effects. Inbreeding levels and FSGS patterns suggest that the species shows a mixed mating system. Family structures defined by full-sib or half-sib saplings spatially clumped could be a consequence of restricted gene dispersal, limited mobility of propagules and spatial recruitment of seedlings. Gene dispersal of plants combine the effects of spatial scales and heterogeneity, temporal scales, and system complexity. Restricted seed dispersal distances, high tree densities and mixed mating system patterns directly influence FSGS levels. Therefore, the knowledge of gene dispersal distances of keystone forest tree species from SDTF is relevant to design sampling strategies in conservation and restoration projects.