CHLOROPLAST DNA POLYMORPHISM SIGNALS COMPLEX INTERSPECIFIC INTERACTIONS IN EUCALYPTUS (MYRTACEAE)

Variation in the chloroplast genome of 44 accessions representing 14 E ucalyptus L'Her. species from the series Viminales (sensu Pryor and Jo hnson 1971) was investigated. Southern analysis of the chloroplast gen omes restricted with 12 enzymes revealed 20 restriction-site polymorph isms of which 7 were autapomorphic to individual trees. The 13 informa tive restriction-site polymorphisms were distributed between individua ls of different species, but none was species-specific. Fourteen chlor oplast haplotypes were identified for south-eastern Australian individ uals. In endemic Tasmanian species, five haplotypes were identified. C hloroplast haplotypes appear to have a mosaic distribution in south-ea stern Australia, more closely associated with geographical regions tha n with morphological species boundaries. The biogeographic distributio n of chloroplast haplotypes may be explained by a combination of inter specific hybridisation and introgression, and convergent evolution. Th e lack of species-specificity of cpDNA variation indicates that, altho ugh cpDNA is not appropriate for species-level phylogeny analysis in t he series Viminales, it may provide useful information in studies of b iogeography and gene flow in Eucalyptus.