Fine-scale genetic structure of Eucalyptus globulus ssp. globulus forest revealed by RAPDs

Fine-scale genetic structure in Eucalyptus globulus ssp. globulus native fo rest was detected using 69 randomly amplified polymorphic DNA (RAPD) marker s. The association between genetic similarity and geographic distance was s tudied among 51 trees from the Tinderbox locality in Tasmania (distance ran ging from 2 m to 4 km apart) and compared to 18 trees from localities up to 100 km away. Twenty pedigreed F(1)s were used as controls to scale the RAP D similarity among individuals to pedigree similarity. The association betw een genetic similarity and geographic distance was weak, yet at Tinderbox, highly related trees were shown to occur within 25 m of one another. There is an abrupt drop in average similarity after about 25 m, with no significa nt change with distances up to 14 km. Nevertheless, Tinderbox trees outside the 25 m genetic patches are still more similar to each other than they ar e to trees from the Mayfield Bay locality 100 km away. These results sugges t that E. globulus native forests have a family group structure, superimpos ed on a noisy, background level of lower relatedness which extends over a w ider geographical range. This study is unique in demonstrating the congruen ce between fine-scale genetic structure as revealed by molecular data and p revious quantitative genetic data.