Demographic Genetics of the Japanese Beech, Fagus crenata, in the Ogawa Forest Preserve, Ibaraki, Central Honshu, Japan. III. Population Dynamics and Genetic Substructuring within a Metapopulation

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Abstract
The demographic genetic structure of a metapopulation of the Japanese beech (Fagus crenata Blume) in the Ogawa Forest Preserve was analyzed using allozyme variabilities as genetic markers. A total of 138 mature trees in an area of 30 ha were first mapped; their DBH was measured and leaf samples were collected and genotyped. A total of 38 multilocus genotypes in a combination of six loci and 22 alleles were detected. Spatial analyses, using Moran's I and coancestry (Rij) showed there was no conspicuous pattern of associations between genetic similarities and individual distances in scales larger than 30 m. In smaller, 5 m interval scales, however, gene dispersal from mother trees to juvenile trees was found in the ranges of 10 to 20 m in distance. The indirect measures of gene flow using multilocus genotypes revealed that most progenies were derived from the nearest patch populations and also from neighboring patch populations. Genetic subdivisions of the Ogawa metapopulation were analyzed on the basis of patch populations (Gst=0.234) and local populations (Gst=0.094), reflecting the effects of population fragmentation. Genetic neighborhood area (A) obtained in Ogawa was 3050–4091 m2, and effective population size (Ne) was 1.2–2.1 mature individuals. A very small Ne in Ogawa may reflect topographic complexity and past artificial disturbances of the habitats.