Population Viability Analysis (PVA) uses computer modelling to simulate interacting deterministic and stochastic factors (e.g. demographic, genetic, spatial, environmental and catastrophic processes) that act on small populations and assess their long-term vulnerability to extinction. The computer program VORTEX was used in a PVA of Leadbeater's possum, Gymnobelideus leadbeateri McCoy, an endangered arboreal marsupial that is restricted to the montane ash forests of the central highlands of Victoria. PVA was used to examine the impacts of changes in the size of subpopulations and the effects of environmental variation. Our analyses demonstrated that an annual linear decline in the carrying capacity in all or parts of the habitat will lead to the extinction of G. leadbeateri in those areas. Mean time to extinction was related to the rate of annual decrease. This conclusion is of practical and management importance as there is presently a decline in suitable habitat because of an annual loss of more than 3.5% of trees with hollows, which provide nest sites for G. leadbeateri. Because nest sites are a factor that limits populations of G. leadbeateri, the species could be lost from large areas within the next 50 years. PVA was also used to determine the viability of populations in areas, such as oldgrowth forest, where there is not likely to be a steady decline in habitat carrying capacity resulting from the loss of trees with hollows. This allowed an analysis of the cumulative impacts of small population size, environmental variation and genetic factors, which showed that, for a 100-year projection, simulated populations of 200 animals or more remained demographically stable and experienced a less than 10% decline in predicted genetic variability. However, the relatively simplified nature of population modelling and the suite of assumptions that underpin VORTEX mean that the probability of extinction of populations of this size may be greater than determined in this study. As a result, it is possible that only populations of more than 200 animals may persist in the long term where suitable habitat can be conserved or established and subsequently maintained without a reduction in carrying capacity.

The eastern barred bandicoot, Perameles gunnii, is functionally extinct on mainland Australia. Conservation of this unique taxon is dependent on reintroduction, based on a managed captive-breeding programme that provides founder animals. Existing reserves at which reintroduction has occurred are too small to support long-term genetically viable populations. Therefore, reintroductions must be made at a number of sites and the resulting populations managed as a metapopulation. A habitat-suitability model has been developed to assess and compare reintroduction sites. This is the first application of this concept to an Australian species. The model is composed of five variables-size, habitat structure, predation, shape and security-values of which are combined in a simple relationship to produce comparable mathematical statements for proposed reintroduction sites. The model has been applied to existing reserves to test their contribution to the recovery programme.

The threatened, free-ranging mainland poplation, of the eastern barred bandicoot in the Hamilton area of Victoria declined to near extinction in late 1992. Demographic changes associated with the decline were monitored from 1988 to 1992. About 200 different animals were captured in 1988,49 in 1989, 16 in 1990, 3 in 1991 and 3 in 1992; capture rates (number of bandicoots captured per trap-night) displayed a similar pattern: 0.5 in 1988,O.l in 1989,0.05 in 1990,0.05 in 1991 and 0.02 in 1992. Observed declines lay within the 5% confidence intervals predicted by a demographic model for a population subjected to a removal rate of 14 animals per three months (the number removed for captive breeding by managers). Removal of bandicoots to stock a captive population hastened the demise of the wild population by about seven years; however, even in the absence of removals of animals, extinction was impending within 5-10 years. Sex ratios were male-biased in all years except 1988; the bias may have resulted from stochastic events. Average litter sizes did not differ between the 1988 population and subsequent populations, except for the 1991 population, in which a predominance of non-reproductive females contributed to a strong decline in average litter size. These demographic trends illustrate how the synergy between stochastic and deterministic forces can rapidly drive a small population to extinction.

Access to consistent, high-quality metadata is critical to finding, understanding, and reusing scientific data. However, while there are many relevant vocabularies for the annotation of a dataset, none sufficiently captures all the necessary metadata. This prevents uniform indexing and querying of dataset repositories. Towards providing a practical guide for producing a high quality description of biomedical datasets, the W3C Semantic Web for Health Care and the Life Sciences Interest Group (HCLSIG) identified Resource Description Framework (RDF) vocabularies that could be used to specify common metadata elements and their value sets. The resulting guideline covers elements of

Access to consistent, high-quality metadata is critical to finding, understanding, and reusing scientific data. However, while there are many relevant vocabularies for the annotation of a dataset, none sufficiently captures all the necessary metadata. This prevents uniform indexing and querying of dataset repositories. Towards providing a practical guide for producing a high quality description of biomedical datasets, the W3C Semantic Web for Health Care and the Life Sciences Interest Group (HCLSIG) identified Resource Description Framework (RDF) vocabularies that could be used to specify common metadata elements and their value sets. The resulting guideline covers elements of