Phylogenetic relationships between two rare acacias and their common, widespread relatives in south-western Australia

Knowledge of phylogenetic relationships between taxa is particularly valuable for conservation management of threatened taxa in an evolutionarily diverse flora such as that found in the south-west of Western Australia. Acacia sciophanes and A. lobulata are two threatened species that have restricted distributions at the edge of the range of their widespread relatives, A. anfractuosa and A. verricula respectively. The phylogeny of these species pairs was investigated using RFLP analysis of cpDNA. Both restricted species were shown to be phylogenetically distinct. Acacia sciophanes and A. anfractuosa are sister species and display the characteristics of a relatively recent evolutionary lineage. In comparison A. lobulata shows significant divergence from A. verricula and is not closely related to the species group in which A. verricula is placed. Acacia lobulata appears to represent an ancient lineage and is most likely a relictual species. Acacia verricula also has characteristics of a more ancient evolutionary lineage than A. sciophanes and A. anfractuosa. If priority setting processes based on phylogenetic principles were to be applied to these species A. lobulata would have the greater biodiversity value for conservation management.