ESTRUTURA GENÉTICA DE Tibouchina papyrus (Pau-papel) EM ÁREAS NATURAIS DE CAMPO RUPESTRE NO CERRADO.

Abstract

(Genetic structure of Tibouchina papyrus (Pohl) Toledo (“pau-papel”) in natural areas of Cerrado rupestrian fields). This paper has the aim describe the genetic of variability of Tibouchina papyrus (Pohl) Toledo local populations, from the regions of “Serra Dourada” and “Serra de Pirineus”, in Goiás State, Central Brazil. The six RAPD primers generated a total of 147 loci, varying from 23 to 26 per primer. The hierarchical evaluation of genetic variability, performed using an Analysis of Molecular Variance (AMOVA) considering the local populations within the two regions (i.e., “Serra dos Pirineus” and “Serra Dourada”), showed an estimate of overall diversity among populations equal to ST=0,3439. The value of divergence between regions ( CT) was equal to 18,96%, so that the variation among local populations within regions was equal to 15,43%. Estimates of gene flow indicates a small number of migrants among local populations per generation. Multivariate analyses (UPGMA and NMDS) indicated that a relationship between genetic and geographical distances exists, which was confirmed by a spatial pattern analysis using Mantel test (r = 0.71; P < 0.015 with 1000 random permutations). Thus, this structure was originated from a stochastic neutral model of population differentiation, in which drift within populations is counteracted by short distance gene flow. Despite strong levels of population structure (i.e., high divergence among populations within regions), the diversity observed support the hypothesis that Tibouchina papyrus is a facultative xenogamous species. For conservation ends of germplasm with base in the preliminary results, it can be suggested the collection of seeds of the most possible number of populations, and in the two appraised areas, because each one contains a singular component of the total genetic variation.