PARTITIONING AND DISTRIBUTION OF RAPD VARIATION IN A FOREST TREE SPECIES, EUCALYPTUS-GLOBULUS (MYRTACEAE)

Eucalyptus globulus is an important species for pulpwood production in many countries. The pattern and partitioning of variation is importan t baseline knowledge for tree breeding. Currently the species is divid ed into four subspecies: globulus, bicostata, pseudoglobulus and maide nii. Random Amplified Polymorphic DNA (RAPD) markers were used to anal yse variation in 173 representatives of 37 natural populations of E. g lobulus: 31 localities of ssp. globulus (148 individuals), two localit ies each of ssp. bicostata (nine individuals), ssp. maidenii (ten indi viduals) and ssp. pseudoglobulus (six individuals). Ten 10-mer primers amplified a total of 162 scorable bands, of which 149 (91.9 per cent were polymorphic. AMOVA analysis of a Euclidean distance matrix based on presence/absence of polymorphic bands found most variation within l ocalities, but significant differences between localities and regions. Principal components analysis (PCA) identified a major latitudinal di ne in RAPD phenotype that differentiated southern Tasmanian localities from other ssp. globulus localities on mainland Australia. Many local ities previously identified as intermediate between subspecies globulu s and other subspecies in morphology were not intermediate in RAPD phe notype. In some cases regions which showed marked differentiation betw een localities in capsule and juvenile leaf morphology showed little R APD differentiation between localities. RAPDs also provided new insigh ts into the affinities of outlying localities. Although RAPD technolog y has not yet been applied to many forest tree species, patterns of va riation were similar to those found in other outcrossing species studi ed using both RAPDs and other molecular markers.