The koala, Phascolarctos cinereus, is a geographically widespread species endemic to Australia, with three currently recognized subspecies: P.c. adustus, P.c. cinereus, and P.c. victor. Intraspecific variation in the mitochondrial DNA (mtDNA) control region was examined in over 200 animals from 16 representative populations throughout the species' range. Eighteen different haplotypes were defined in the approximately 860 bp mtDNA control region, as determined by heteroduplex analysis/temperature gradient gel electrophoresis (HDA/TGGE). Any single population typically possessed only one or two haplotypes yielding an average within-population haplotypic diversity of 0.180 +/- 0.003, and nucleotide diversity of 0.16%. Overall, mtDNA control region sequence diversity between populations averaged 0.67%, and ranged from 0% to 1.56%. Nucleotide divergence between populations averaged 0.51%, and ranged from 0% to 1.53%. Neighbour-joining methods revealed limited phylogenetic distinction between geographically distant populations of koalas, and tentative support for a single evolutionarily significant unit (ESU). This is consistent with previous suggestions that the morphological differences formalized by subspecific taxonomy may be interpreted as clinal variation. Significant differentiation in mtDNA-haplotype frequencies between localities suggested that little gene flow currently exists among populations. When combined with microsatellite analysis, which has revealed substantial differentiation among koala populations, we conclude that the appropriate short-term management unit (MU) for koalas is the local population.

SUMMARYDetermining the information content of vocal signals and understanding morphological modifications of vocal anatomy are key steps towards revealing the selection pressures acting on a given species' vocal communication system. Here, we used a combination of acoustic and anatomical data to investigate whether male koala bellows provide reliable information on the caller's body size, and to confirm whether male koalas have a permanently descended larynx. Our results indicate that the spectral prominences of male koala bellows are formants (vocal tract resonances), and show that larger males have lower formant spacing. In contrast, no relationship between body size and the fundamental frequency was found. Anatomical investigations revealed that male koalas have a permanently descended larynx: the first example of this in a marsupial. Furthermore, we found a deeply anchored sternothyroid muscle that could allow male koalas to retract their larynx into the thorax. While this would explain the low formant spacing of the exhalation and initial inhalation phases of male bellows, further research will be required to reveal the anatomical basis for the formant spacing of the later inhalation phases, which is predictive of vocal tract lengths of around 50cm (nearly the length of an adult koala's body). Taken together, these findings show that the formant spacing of male koala bellows has the potential to provide receivers with reliable information on the caller's body size, and reveal that vocal adaptations allowing callers to exaggerate (or maximise) the acoustic impression of their size have evolved independently in marsupials and placental mammals.

Habitat fragmentation can act to cause reproductive isolation between conspecifics and undermine species' persistence, though most studies have reported the genetic condition of populations that have already declined to a very small size. We examined genetic diversity within the vulnerable, declining koala (Phascolarctos cinereus) population in Southeast Queensland, Australia to determine the genetic impact of ongoing threatening processes. Five hundred and twelve koalas from ten Southeast Queensland Local Government Areas on the mainland and one island were genotyped at six polymorphic microsatellite loci. Based on Bayesian cluster analysis incorporating spatial data, the regional koala population was subdivided into six clusters, with location of major roads and rivers appearing to be consistent with being barriers to gene flow. The distribution of mtDNA control region haplotypes identified distinct coastal and inland clades suggesting that historically there was gene flow between koalas along the coast (though little interchange between coastal and inland animals). In contrast, koalas from the Koala Coast (Brisbane City, Logan City and Redland Shire) were shown by microsatellite analysis to be genetically distinct from adjacent areas. It is likely, therefore, that more recent reductions in population size and restricted gene flow through urbanisation have contributed to the genetic differentiation of koalas in the Koala Coast region.

Global Positioning System (GPS) wildlife telemetry collars are being used increasingly to understand the movement patterns of wild mammals. However, there are few published studies on which to gauge their general utility and success. This paper highlights issues faced by some of the first researchers to use GPS technology for terrestrial mammal tracking in Australia. Our collated data cover 24 studies where GPS collars were used in 280 deployments on 13 species, including dingoes or other wild dogs (Canis lupus dingo and hybrids), cats (Felis catus), foxes (Vulpes vulpes), kangaroos (Macropus giganteus), koalas (Phascolarctos cinereus), livestock guardian dogs (C. l. familiaris), pademelons (Thylogale billardierii), possums (Trichosurus cunninghami), quolls (Dasyurus geoffroii and D. maculatus), wallabies (Macropus rufogriseus and Petrogale lateralis), and wombats (Vombatus ursinus). Common problems encountered were associated with collar design, the GPS, VHF and timed-release components, and unforseen costs in retrieving and refurbishing collars. We discuss the implications of collar failures for research programs and animal welfare, and suggest how these could be avoided or improved. Our intention is to provide constructive advice so that researchers and manufacturers can make informed decisions about using this technology, and maximise the many benefits of GPS while reducing the risks.

No abstract