title: Seed gene flow and fine-scale structure in a Mediterranean pine ( Pinus pinaster Ait.) using nuclear microsatellite markers.
abstract: The Mediterranean populations of maritime pine ( Pinus pinaster Ait.) are typically small and have a scattered distribution, being threatened by human activities and forest fires. In the framework of the genetic-resources conservation program of this species, a native multi-age stand located in a Mediterranean area (central Spain) was studied using three highly polymorphic nuclear microsatellites (SSRs). Spatial autocorrelation analysis was conducted using Moran's index in order to detect fine-scale structure in both natural regeneration and mature trees. The spatial pattern of seed flow based on dispersed progeny was studied using a highly reliable subset of parent-offspring matches obtained by means of parentage analysis and simulation-based calculation of statistical confidence. Maritime pine showed a fine-scale structure at the seedling stage. In natural regeneration, the autocorrelograms indicated a patch size of approximately 10 m. The fine-scale structure seems to be produced by a restricted seed gene flow. In fact, there was an excess of parent-offspring matches in a radius of 15 m from the parent trees. Pines with a heavy seed, such as P. pinaster, are expected to have a short dispersal distance, thus producing a fine-scale structure. However, the fine-scale structure did not persist in the mature trees. Within-population genetic structure in Mediterranean pines may be affected by a number of post-dispersal events (e.g. mortality due to the severity of the Mediterranean climate and animal-mediated secondary dispersal during the summer period). Thus, great alteration in the pattern produced by the initial seed rain and differences in genetic structure between tree cohorts are expected.
authors.affiliation: Departamento de Mejora Genética y Biotecnología, INIA, P.O. 8111, 28080 Madrid, Spain.
authors.forename: C.
authors.initials: C
authors.lastname: González-Martínez
authors.forename: S.
authors.initials: S
authors.lastname: Gerber
authors.forename: T.
authors.initials: T
authors.lastname: Cervera
authors.forename: M.
authors.initials: M
authors.lastname: Martínez-Zapater
authors.forename: L.
authors.initials: L
authors.lastname: Gil
authors.forename: R.
authors.initials: R
authors.lastname: Alía