Multifaceted genetic analysis of the "Critically Endangered" brush-tailed rock-wallaby Petrogale penicillata in Victoria, Australia: implications for management

The use of molecular genetic techniques can aid wildlife managers in setting priorities and devising management strategies for scattered populations of threatened taxa. In this study, six remnant populations of the "critically endangered" brush-tailed rock-wallaby (Petrogale penicillata) in Victoria, Australia, were examined using karyotypic, microsatellite (11 loci) and mitochondrial DNA (mtDNA) control region sequence analysis. Each remnant population was found to be genetically distinct (unique microsatellite alleles and control region haplotypes), but had low genetic diversity. This distribution of genetic diversity between, rather than within populations, is most likely a consequence of recent severe reductions in population size and dispersal that have occurred since European settlement. The six mtDNA control region haplotypes identified in the Victorian populations were all closely related (average 1.3% sequence divergence), and only 2% divergence separated haplotypes from East Gippsland and the Grampians (550 km to the west). In contrast there was considerable sequence divergence (7.7%) between the Victorian haplotypes and those found in P. penicillata from elsewhere in the species range. In comparison, 8.8% divergence separates P. penicillata from the closely related P. herberti. The Victorian haplotypes also formed a distinct and well supported monophyletic group that excluded haplotypes from other P. penicillata and P. herberti. In light of these data, we recommend that the remnant Victorian populations of P. penicillata be managed separately from remaining populations in New South Wales and Queensland; and that individuals be regularly exchanged amongst the Victorian populations to increase their diversity and reduce the likelihood of inbreeding depression.