Population ecology and genetics of the vulnerable Acacia attenuata (Mimosaceae) and their significance for its conservation, recovery and translocation

Abstract

Acacia attenuata Maiden and Blakely, is a vulnerable shrub, endemic to south-east Queensland, Australia. The population ecology and genetics of the species were examined throughout its range to assist with conservation and recovery of the species. South-east Queensland is experiencing massive population expansion and the associated housing and infrastructure development is having an impact on the remnant vegetation in the region. Population sizes differed significantly (P < 0.05) and were smaller in the southern urbanised parts of the species distribution. Genetic diversity of A. attenuata was high in comparison to other Acacia species. Genetic diversity was not significantly correlated with population size or isolation. There was a high degree of genetic similarity among populations (FST = 0.101). Populations were effectively inbred (F = 0.482); however, inbreeding was not correlated with population size, density, isolation or reproductive activity. Uniform high levels of genetic diversity and low population differentiation suggest that A. attenuata once had a more continuous distribution. A population that was due to be translocated because of a development decision was also assessed as part of the research. The population at the development site (AA14 – Bundilla) was the largest and one of the most genetically variable sites, thus the genetic diversity of the population needs to be conserved within the translocation. The translocation process is reported here and occurred based on the information on genetics and ecology provided by this study. Population density and the proportion of seedlings and juveniles were significantly negatively correlated with time since fire. Fire regimes of 5–10 years are optimal for A. attenuata population regeneration and persistence, thus active fire management will be required for both the translocated population and for other populations within the urban and peri-urban areas, where competing demands make fire management controversial and difficult.