Estrutura Filogeográfica de populações de Roupala montana Aublet. (Proteaceae), em áreas de savanas da Amazônia e Brasil central

Abstract

Disjoint savannas found within the Amazon rainforest have been interpreted as biogeographic evidence of expansion and retraction of this type of dry vegetation as a consequence of climatic fluctuations during the Quaternary Period. Little is known, however, about the diversity of isolated savannas in the Amazon and how the gene flow between savannas isolated from the Amazon and continuous savannas from Central Brazil varied in time and geographical space. In this study, the genetic diversity and population structure of the arboreal species Roupala montana was investigated in savanna areas of Central Brazil and in isolated savanna enclaves in the Brazilian Amazon. For this, genetic variation at three microsatellite loci and two non-coding regions (psbA /trnH and trnG /trnS) of the chloroplast genome were analysed. In total, 170 individuals from 25 populations of R. montana were sampled. It was found high genetic diversity which was evidenced by the occurrence of 39 haplotypes for microsatellites and 26 haplotypes for non-coding regions of the cpDNA. For the microsatellite data, only eight haplotypes were shared between the core savannas in Central Brazil and isolated Amazonian savannas. For cpDNA sequencing data, no haplotype sharing was found between the savannas of these two regions. The results suggest, the occurrence of long-term isolation among the Amazonian savannas and also between these and the savannas of Central Brazil. A high number of exclusive haplotypes and high genetic differentiation was evidenced for the populations of R. montana sampled. The disjoint savannas in the Amazon seems to have been colonized by lineages of R. montana from the "core" Central Brazil savannas, emphasizing that, there was a connection between these regions which probably allowed the dispersion of the species. Each set of isolated savanna fragment in the Amazon are redoubts of unique genetic lineages and the patterns of distribution of genetic variability found may serve as a basis for the definition of conservation strategies for Brazilian savannas in general.