Spatial genetic structure in fourPinusspecies in the Sierra Madre Occidental, Durango, Mexico

Abstract

In this study, we examined the spatial genetic structure (SGS) in extensively managed, but naturally regenerated forest stands of Pinus cembroides Zucc., Pinus discolor Bailey et Hawksworth, Pinus durangensis Martínez, and Pinus teocote Schiede ex Schltdl. & Cham. at local (within the stands) and large (among the stands) scales using amplified fragment length polymorphisms (AFLP), with respect to conservation and sustainable management of genetic resources of these species. Because these four pine species grow in different landscape structures, we expected to find differences in their SGS, although all of them are widely spread, wind pollinated, and often occur at high population densities. At the local scale, there was no evidence of significant SGS in the four species under study (except in 1 out of 18 seed stands), suggesting that the genetic variants of these species are almost always randomly distributed in space, probably due to high wind pollination and seed dispersal. At a larger scale, the significant SGS found may be the result of isolation by distance among populations. We recommend (i) establishing a tight network of seed stands, with a maximum distance of 3–11 km between seed stands, to prevent greater loss of local genetic structure, and (ii) using these seeds to establish reforestations within a maximal radius of 3–5 km from seed provenances.