Population genetic studies on indigenous conifers in Korea

Abstract

Studies on the genetic variation in tree populations have been greatly facilitated by the development of molecular markers. Allozyme and DNA markers have been employed to estimate the level of genetic diversity and characterize the distribution patterns of genetic variation within and among populations. They have also been applied to examine the dispersal patterns and mating systems influencing the degree of population differentiation. We reviewed 18 population genetic studies on 8 native Korean conifers (Pinus densiflora, P. thunbergii, P. koraiensis, P. pumila, Abies holophylla, A. koreana, Taxus cuspidata, and Torreya nucifera), which appeared in the literature between 1992 and 2005. The level and distribution patterns of genetic variation observed in the 8 conifers were comparable with those reported in studies on other conifers. From studies on allozyme markers, the expected heterozygosity ranged from 0.168 to 0.262 for Taxus cuspidata and Pinus densiflora, and the degree of genetic differentiation between populations (GST) ranged from 0.031 to 0.067 for Pinus densiflora and Taxus cuspidata, respectively. From studies on the DNA markers of I‐SSR, the genetic diversity (Shannon's Index) ranged from 0.306 to 0.478 for Pinus koraiensis and Taxus cuspidata, respectively, and most of genetic variations were allocated within populations with FST values (i.e., degree of population differentiation) ranging from 0.066 to 0.198 for Pinus densiflora and Abies holophylla, respectively. Although the multilocus outcrossing rate (t m) of Pinus densiflora was 0.860, based on allozymes, suggesting a high level of outcrossing, highly correlated outcrossed paternity (r p=0.874) and evidence of biparental inbreeding (t m‐t s=0.115) were also verified. A study on the spatial autocorrelation of a scattered Korean pine (Pinus koraiensis) stand with relatively low density revealed a significant spatial genetic structure at distances between 24 and 32 m. At the allozyme level, the species with limited distributions tended to show less genetic diversity, but a higher level of genetic differentiation (G ST). For DNA markers, this tendency was not marked.