Richard A. How

Human migration is important in the international spread of exotic Salmonella serovars in animal and human populations.

SUMMARY The exposure of indigenous humans and native fauna in Australia and the Wallacea zoogeographical region of Indonesia to exotic Salmonella serovars commenced during the colonial period and has accelerated with urbanization and international travel. In this study, the distribution and prevalence of exotic Salmonella serovars are mapped to assess the extent to which introduced infections are invading native wildlife in areas of high natural biodiversity under threat from expanding human activity. The major exotic Salmonella serovars, Bovismorbificans, Derby, Javiana, Newport, Panama, Saintpaul and Typhimurium, isolated from wildlife on populated coastal islands in southern temperate areas of Western Australia, were mostly absent from reptiles and native mammals in less populated tropical areas of the state. They were also not recorded on the uninhabited Mitchell Plateau or islands of the Bonaparte Archipelago, adjacent to south-eastern Indonesia. Exotic serovars were, however, isolated in wildlife on 14/17 islands sampled in the Wallacea region of Indonesia and several islands off the west coast of Perth. Increases in international tourism, involving islands such as Bali, have resulted in the isolation of a high proportion of exotic serovar infections suggesting that densely populated island resorts in the Asian region are acting as staging posts for the interchange of Salmonella infections between tropical and temperate regions.

Living in isolation: Ecological, demographic and genetic patterns in northern Australia's top marsupial predator on Koolan Island

Koolan Island supports an abundant population of the threatened northern quoll (Dasyurus hallucatus). We used a mark–release–recapture program that produced 2089 captures from 2009 to 2012 to examine demographic and genetic parameters in this insular population and compare to other localities. Every captured female was either lactating or carrying up to eight young over the breeding season, July–September. Unlike several other populations, males on Koolan Island can survive long after breeding, but never into a second breeding season. Females can survive and reproduce for two successive annual breeding seasons and occasionally survive to a third. There is marked sexual dimorphism but it is less pronounced, and both sexes are smaller than their mainland counterparts. Quolls were recorded moving over 4 km and apparent abundance was far higher on Koolan Island than the mainland. Genetic analyses of nuclear and mitochondrial markers demonstrate a distinctive signature. Koolan island has only 34% of the allelic richness of the entire species, and only 38% of the alleles in Kimberley mainland and near-shore island populations. There is no evidence of recent or long-term population decline. Kimberley island faunas have distinctive demographic and genetic profiles that should be appraised before considering translocations for conservation purposes.

The burrowing bettongs of Barrow Island: demographic and genetic insights into a threatened macropod

Abstract. Islands provide the last refuge for many Australian species that have succumbed to range contractions since European settlement. These species have heightened vulnerability when developments are planned for the islands. The burrowing bettong (Bettongia lesueur), a threatened macropod, was once widespread across Australia but now occurs naturally only on Barrow Island and two other Western Australian offshore islands. Here, we document the demographic, social and genetic characteristics of the Barrow Island population, using nuclear microsatellites, mtDNA and demographic parameters from 286 individuals trapped around 29 warrens. The Barrow Island population utilises complex warren systems scattered across the landscape and exhibits continuous breeding, even during extensive dry conditions. Males (759 g) were significantly heavier than females (735 g), with the latter reaching sexual maturity at ∼600 g. Warrens varied markedly in size and number of individuals, with 20% of females and 25% of males moving between nearby warrens. There were two deep mtDNA haplotype clades that coalesce around 298 000 years ago, indicating that this island population has maintained an effective population size that has permitted the retention of one marked feature of its preisolation genetic diversity. Dispersal and gene flow between warrens was severely constrained. Both mtDNA and 11 nuclear microsatellites showed a strong isolation by distance effect, with genetic differences between warrens increasing linearly with geographic separation. While this was marked in both sexes, it was stronger in females and consistent with shorter dispersal distances for females than for males. The trapping and genetic data are concordant, with between-warren sociality correlated with genetic similarity. Long-term conservation, management and translocation programs will benefit from cognisance of the strong fidelity to natal areas, as evidenced by both recapture data and genetic analyses.