Chloroplast DNA reveals complex interspecific relationships within Eucalyptus series Viminales

Eucalyltus L’Herit. is probably the best known and most important genus in Australia, with over 500 species. The series Viminales (subgenus Symphyomyrtus) sensu Proyor and Johnson (1971) contains ca. 40 species (including Australia’s most important hardwood species, e.g., E. nitens and E.alobulus),. characterised by markedly different adult and juvenile foliage. Despite numerous morphological and chemical studies, the delimitation and subdivision of species within Series Viminales remain problematic. A recent study of cpDNA of E nitens revealed a high level of intraspecific polymorphism, cautioning that cpDNA may not be appropriate for phylogenetic analysis. It was suggested that some -of the cpDNA variation observed within E.nitens may be derived from hybridisation with other Eucaylypus species, with subsequent introgression of the chloroplast genomes. The aim of the current study of Series Viminales was to determine the levels of inter- and intra-specific polymorphism of cpDNA, to test whether morphological species can be identified as monophyletic groups on the basis of their cpDNA, and to test for introgression of cpDNA between species