Diversidade e estrutura genética de populações naturais de Araucaria angustifolia (Araucariaceae) no estado de Minas Gerais

Abstract

Araucaria angustifolia (Bert.) O. Ktze is an endemic gymnosperm from Brazil, which is widespread in Southern landscapes, and restricted in the Southeast. It is popularly known as Brazilian pine, with a peculiar architecture, beauty and size of adult trees; making forests with Araucaria a unique ecosystem. The Southern Minas Gerais is part of the north boundary of the distribution of this tree species in Brazil, and genetic information related to its population is important for conservation, because these areas may contain adaptive genes restricted to these locations; which should be preserved due to high destruction and fragmentation of these ecossystens. This tree specie is considered endangered on the Oficial List of IBAMA (Ministry of Environment, 2008), and it has been classified as vulnerable to extinction in Minas Gerais (COPAM 085/97). In this study, we aimed to quantify levels of diversity and genetic structure of remaining population of Araucaria angustifolia located in the Serra da Mantiqueira, Southern Minas Gerais, using microsatellite markers (SSR). Studies about genetic diversity and structure were performed on 450 individuals distributed in 9 different populations of A. angustifolia. Eight SSR primers were used to generate 65 alleles. The genetic data point out that the remaining areas retain a high genetic diversity so far (He = 0.77). The analysis of molecular variance indicated that the majority of genetic diversity, about 90%, occurs within populations. There was no significant correlation between genetic and geographic distances (r = 0.08939 p = 0.6749). The inbreeding was not detected (f = - 0.09). The Bayesian analysis indicated that the genetic diversity was distributed in two genetic groups (k = 2). The genetic bottleneck was identified in eight of sampled populations. Gene flow barriers were detected, probably due to presence of mountains. The genetic structuring was found in four of sampled populations. The high genetic diversity retained in populations indicates that still existing genetic variability of A. angustifolia in sampled areas, therefore, this variability will be maintained if there is planting or regeneration management.