Demographic genetics of the American beech, Fagus grandifolia. II. Genet substructure of populations for the Blue Ridge, Piedmont and the Great Smoky Mountains

Abstract

Populations of American beech in Virginia and the Great Smoky Mountain National Park in Tennessee and North Carolina were investigated for demographic genetic substructurings. Two Virginia populations, one on the Blue Ridge (WG1) and the other on the Piedmont (WG2) occur over an elevational gradient of several hundreds meters. One of the Great Smoky Mountain populations (GS1) was in a ‘beech gap’ and the other (GS2) in a ‘cove forest’ along a creek. The populations in the Great Smoky Mountain National Park were only separated by a few hundred meters in elevation, but both on the same physiographic province. The populations had two growth forms. Trees produced extensive root suckers at WG1, GS1 and GS2, but WG2 had no root suckers and all individuals had obviously been established from seeds. A total of 1335 shoots were mapped at the four sites, their size measured [diameter at breast height (DBH) or diameter at ground height (DGH)], and genotypes were determined for each locus using allozyme analysis. FIS among five different size‐classes revealed an excess of homozygotes in WG1, GS1 and GS2, and an excess of heterozygotes in WG2. The offshoot formation from root suckers obviously contributed to the abundance of intermediate size‐classes in WG1, GS1 and GS2. Exceedingly localized patchiness of different multilocus genotypes reveals genetic clustering of shoots that have obviously originated from root suckers in WG1, GS1 and GS2. The Piedmont population (WG2), on the other hand, showed loose localization of genetically related trees at a scale of 35–40 m in area, suggesting broader ranges of pollen and seed dispersal. The data are discussed in the light of the differences in growth form and mode of reproduction, and also in relation to the post‐glacial migration and the current geographic distribution of the species.

Demographic genetics of the American beech (Fagus grandifolia Ehrh.) III. Genetic substructuring of coastal plain population in Maryland

“…7a) compared to root suckering populations (Kitamura et al . 2000) were more or less identical to the Piedmont population (Kitamura et al . 2001), which also does not show root sucker formation.…”

“…Our previous demographic genetic studies of the American beech have revealed that there occur unique but diverse spatiotemporal genetic substructures related to its reproductive systems as noted (Kitamura et al . 2000, 2001).…”

“…In the present series of studies, we have consistently used multilocus genotypes to demonstrate clonal substructures in the patch or local populations, and also size‐class discrimination was introduced to show chronological genetic differentiation among different size‐classes, i.e. different generations (Kitamura et al . 2000, 2001).…”

“…The present study, as one in a series of demographic genetic analyses of the American beech populations, attempts to examine the demographic genetic structures of the coastal plain populations in Maryland, focusing on the aspects of recovery, and maintenance mechanisms of genetic variations within a local population during the process of secondary succession (Kitamura et al . 2000, 2001; Kitamura & Kawano 2001).…”

Genetic variation in Fagus multinervis Nakai (Fagaceae), a beech species endemic to Ullung Island, South Korea

“…1988; Comps et al . 1990; Leonardi & Menozzi 1995, 1996), F. grandifolia (Houston & Houston 1994; Kitamura et al . 1998, 2000, 2001, 2003; Kitamura & Kawano 2001) and F. crenata (Kawano & Kitamura 1997; Kitamura et al .…”