PHENOTYPIC VARIATION OF NATURAL Pinus oocarpa Schiede ex Schltdl. POPULATIONS IN CHIAPAS

Abstract

According to the NOM-059 Mexican Official Standard, Pinus oocarpa is not an endangered species; however, its locally adapted populations are considerably valuable as genetic resources and are currently object of severe destruction due to the change of land use. For this reason a study was carried out in three of its natural populations with the purpose of determining the phenotypic variations between them. Twelve morphological variables –i.e. five mensuration, three cone and four needle variables– were assessed, and multivariate variance, principal component and grouping analyses were practiced. Significant differences (P<0.01) were found among the populations of Motozintla, General Leyva and Corazón del Valle, according to the mensuration, needle and cone variables. Variation in the mensuration characteristics is linked to environmental factors. The variations in the needles and cones show that it is very likely that the populations of Motozintla and of General Leyva belong to the same genetic unit and are closely linked to the populations of Central America. The inherent variation observed in the cones and needles of Corazón del Valle may be due strictly to a local adaptation to a subhumid warm climate made possible by the great ecological plasticity of the species.