GENETIC STRUCTURE AND DIVERSITY OF Pinus engelmannii Carr. POPULATIONS IN CHIHUAHUA, MEXICO

Abstract

The assessment of the genetic structure and diversity of forest species contributes to the formulation of strategies that preserve their genetic richness. In turn, genetic richness significantly contributes to the adaptation of species to new factors or environments derived from climate change. The objective of this study was to assess the structure and genetic diversity of three Pinus engelmannii populations in the state of Chihuahua, Mexico. The populations are located in the municipalities of Madera, Bocoyna and Balleza at the North, Center and South of the state, respectively. Thirty trees from the three populations were analyzed using AFLP (amplified fragment length polymorphism) molecular markers. Results revealed that P. engelmannii presents a high level of diversity (Shannon index I = 0.380, expected heterozygosity H_e = 0.249). The population from the center showed differences (P ≤ 0.05) in the level of diversity (I = 0.364 and H_e = 0.237) compared to populations from the North and South. Meanwhile, the Northern and Central populations did not show significant genetic differentiation (P = 0.28), while the Southern population was different to the Central (P < 0.045) and Northern populations (P < 0.001). The mountainous systems and canyons in the South of the state seem to act as a geographic barrier that decreases the genetic flow of the Central and Northern populations with their Sothern counterpart, with values of 5.74 and 3.38 N_m, respectively. The genetic structure found in the P. engelmannii populations suggests that reforestation programs in the Southern region of the state of Chihuahua should be carried out using local materials. In contrast, reforestation at the Central and Northern areas can be carried out with materials from both regions, in order to preserve the structureand genetic diversity of this species.