Genetic structure in loblolly pine stands: Allozyme variation in parents and progeny

Genetic population structure in two adjacent old-field stands of loblolly pine was studied by analyzing allele frequencies for eight polymorphic isozyme loci. The stands represented different generations with trees in the older stand being parents of trees in the younger one. The parental stand consisted of three fairly distinct age classes which differed significantly in allele frequencies for four of the allozyme loci, yet no differences were found among the spatial divisions studied. Within the progeny stand, no genetic differentiation was detected with respect to either age class or spatial grouping. Although allele frequencies did not differ between the two stands, genetic population structure was not the same, demonstrating that local genetic structure can differ between successive generations and that varying structures can exist in localized regions. Evidence suggesting a low level of inbreeding was found in both stands.