Chloroplast DNA phylogeography of Eucalyptus globulus

The pattern of variability in chloroplast DNA (cpDNA) of Eucalyptus globulu s Labill. (Myrtaceae) was studied using 270 samples from southern Australia . Forty variable sequence characters were found, defining 105 haplotypes. H aplotypes were assigned to three major cpDNA clades based on their phylogen y. The pattern of cpDNA variation did not conform to subspecies boundaries; however, there was a strong geographic structure to the distribution of cl ades and haplotypes. One clade (J(C)) was geographically central and widesp read and was found in 163 samples from Tasmania and continental Australia. Less-common clades occurred in more localised regions-southern (J(s), 77 sa mples) and eastern (J(et), 12 samples). The distribution of the J(et) and J (s) clades coincides with hypothesised glacial refugia in Tasmania, suggest ing limited seed-mediated dispersal since deglaciation.