The role of fruit bats in the transmission of pathogenic leptospires in Australia

Although antileptospiral antibodies and leptospiral DNA have been detected in Australian fruit bats, the role of such bats as infectious hosts for the leptospires found in rodents and humans remains unconfirmed. A cohortdesign, replicated survey was recently conducted in Far North Queensland, Australia, to determine if the abundance and leptospiral status of rodents were affected by association with colonies of fruit bats (Pteropus conspicillatus spp.) via rodent contact with potentially infectious fruit-bat urine. In each of four study areas, a ‘colony site’ that included a fruit-bat colony and the land within 1500 m of the colony was compared with a ‘control site’ that held no fruit-bat colonies and was .2000 m from the nearest edge of the colony site. Rodents were surveyed, for a total of 2400 trap-nights, over six sampling sessions between September 2007 and September 2008. A low abundance of rodents but a high carriage of leptospires in the rodents present were found to be associated with proximity to a fruit-bat colony. For example, means of 0.4 and 2.3 fawn-footed melomys (Melomys cervinipes) were collected/100 trap-nights at sites with and without fruit-bat colonies, respectively (P,0.001), but the corresponding prevalences of leptospiral carriage were 100% and 3.6% (P,0.001). Such trends were consistent across all of the sampling sessions but not across all of the sampling sites. Leptospires were not isolated from fruit bats by culture, and the role of such bats in the transmission of leptospires to rodents cannot be confirmed. The data collected do, however, indicate the existence of a potential pathway for transmission of leptospires from fruit bats to rodents, via rodent contact with infectious fruit-bat urine. Fruit bats may possibly be involved in the ecology of leptospires (including emergent serovars), as disseminators of pathogens to rodent populations. Stringent quantitative risk analysis of the present and similar data, to explore their implications in terms of disease prevalence and wildlife population dynamics, is recommended

Koala conservation in Queensland, Australia: A role for assisted gene flow for genetic rescue?

The koala is an iconic Australian marsupial that is facing declining populations through habitat loss, disease and predation. Genetic diversity is expected to decline in small, isolated populations, and this is already evident in some restricted koala populations. Gene flow among patches is essential to maintain genetic diversity, and while this can be achieved through habitat connectivity and reduction of threats, a more active approach of assisted gene flow can be considered. Here, the koala population is evaluated for its readiness to undergo purposeful movement of koalas in the processes of genetic rescue and genetic restoration. There is limited data on the fitness consequences of low genetic diversity or hybridisation in koalas, and no known adaptive alleles. However, the adaptability of the koala to captive conditions might assist a living genome bank approach

Phylogenetics, population structure and genetic diversity of the endangered southern brown bandicoot (Isoodon obesulus) in south-eastern Australia

The southern brown bandicoot (Isoodon obesulus) has undergone significant range contractions since European settlement, and it is now considered "Endangered" throughout south-eastern mainland Australia. This species currently has a highly fragmented distribution inhabiting a mosaic of habitats. This project uses mitochondrial DNA (mtDNA) and microsatellite data to determine levels of genetic diversity, population structure and evolutionary history, which can aid wildlife managers in setting priorities and determining management strategies. Analyses of genetic diversity revealed low levels of mtDNA variability (mean h=50.42%, π=0.76%) and divergence (mean dA=0.29%) across all regions investigated, and was among the lowest recorded for marsupials. These data indicate a relatively small female effective population size, which is most likely a consequence of a large-scale population contraction and subsequent expansion occurring in pre-history (mismatch distribution analysis, SSD P-value=0.12). Individuals from the Sydney region experienced significant reductions in microsatellite diversity (A=3.8, HE=0.565), with the Garigal National Park (NP) population exhibiting "genetic reduction signatures" indicating a recent population bottleneck. Population differentiation analysis revealed significant genetic division amongst I. obesulus individuals from Sydney, East Gippsland and Mt Gambier regions (theta=0.176–0.271), but could not separate the two Sydney populations (Ku-ring-gai NP and Garigal NP). Based on these data and habitat type, translocations could readily be made between the two Sydney populations, but not between the others. Phylogenetic comparisons between I. obesulus and I. auratus show little support for current Isoodon taxonomy, consistent with the findings of Pope et al. 2001. We therefore recommend the recognition of only three I. obesulus sub-species and suggest that these comprise a single morphologically diverse species that once was widespread across Australia