Visiting Scientists

Valderês de Sousa

Associated to Labex Scientist Alfredo Augusto Alves

Methods to assess the genetic diversity, sampling, and genetic erosion in populations of Araucaria angustifolia

Research team: Valderês de Sousa – Embrapa Forestry, Colombo, PR; and Christopher Richards – NCGRP/ARS, Fort Collins CO.

Objective: To characterize genetically, via molecular markers, the native populations of Araucaria angustifolia and germplasm banks, aiming to develop models to collect samples for conservation and support a breeding program.

Approach: Materials used: (1) Lyophilized cambium of two tests of provenances/progenies of Araucaria angustifolia. The first, with a total of 192 trees and the second, represented by 222 trees; (2) 336 samples of endosperms from 42 trees (8 endosperms per tree) collected in the population of Camanducaia-MG; (3) Cambium from 120 native trees in a preserved forest of Araucaria (3 plots with 40 individuals each); from 120 individuals from an explored native forest; and from 120 adult
trees of Araucaria collected in a pine plantation. These materials were used for sampling studies, aimed at genetic conservation and genetic erosion studies by comparing the population structure of the preserved forest with the structure of the areas explored in different circumstances. The study used the methodology routinely used for Brassica, in the laboratory of genetics and genomics of NCGRP. And some adjustments were made for cambium and endosperm lyophilized, since the papers published in this species involved only fresh tissues (needles, endosperm, embryo and cambium). SSR genotyping was conducted and the data was analyzed using several complimentary approaches. Descriptive statistics among sampling sites were used to develop ranking to genetic diversity. Additionally genetic diversity was partitioned non-hierarchically to estimate the size and composition of genetic clusters using a Bayesian assignment method. Finally genetic distances between individuals were correlated with pair-wise least cost path distances derived from niche quality models.

Results: These models were used to weight spatial distances and to identify barriers to gene flow among the north and south regions in the range and to correlate these barriers to long-term biogeographic processes that have influenced the flora of southern Brazil. These data have important implications on future conservation planning for this species. Results from these data also have an important role in supporting forestry tree improvement programs. Publication of 1 abstract and presentation of 1 poster at the ‘International Conference Molecular Biology’, in Vienna, Austria, Feb. 4-7, 2012 (http://www.vipca.at/MOLECOL).