Defining entities in the Acacia saligna (Fabaceae) species complex using a population genetics approach

Traditional morphological taxonomic classification is problematic in the Acacia saligna (Labill.) H. L. Wendl. species complex. Reliable identification of entities within the species is essential due to its extensive use both in Australia and overseas, its propensity for weediness, and its ongoing development for use in agroforestry. We used a Bayesian analysis approach to assess genetic structure in populations across the species natural range and to define the natural distributions of various genetic entities. The results indicate that three highly divergent genetic entities are apparent in the A. saligna species complex with further fine-scale genetic subdivision present within two. The three primary genetic entities correspond to the informally described subsp. 'saligna' and subsp. 'pruinescens' combined, subsp. 'stolonifera', and subsp. 'lindleyi'. Within this primary structure two further entities are apparent; one separating subsp. 'saligna'/'pruinescens' into eastern and western populations and the other distinguishing north-western 'lindleyi' populations from the rest of that subspecies distribution. The north-western catchments may have been an important refugium for the species diversity. The results of the study will aid in breeding programs, conservation of natural populations and control of invasive populations of this taxon.