Natasha Tay

Among marsupials, the endangered numbat (Myrmecobius fasciatus) is the only obligate myrmecophage with a diet comprised strictly of termites. Like many other specialised myrmecophagous mammals, numbats have a gracile and highly specialised skull morphology with an elongated rostrum and small braincase. Myrmecobiidae is one of four taxonomic families within the Australasian marsupial order Dasyuromorphia, and to date, the muscular anatomy of any member of this group is relatively poorly known. We utilised microdissection and contrast-enhanced microcomputed tomography scanning to provide the first comprehensive qualitative and quantitative descriptions of jaw muscle anatomy in numbats and quolls (Dasuyrus species). The arrangement of the jaw muscles across these species was conservative, both in gross anatomy and muscle proportions, corresponding to a 'generalised' mammalian pattern. In contrast to Dasyurus, the jaw muscles of the numbat were greatly reduced. Many aspects of the muscle anatomy of the numbat were similar to patterns reported in other myrmecophagous species, particularly a greatly reduced temporalis muscle. Unusually, the digastric muscle in the numbat was comprised of a single, large anterior belly while the posterior belly was absent. We propose that the enlarged anterior belly of the digastric may be linked to jaw stabilisation and coordination of tongue movements during feeding. The lateral insertion and fascial connection of the digastric to the tongue in numbats may also aid in distributing stress evenly across the jaw and minimise muscle fatigue. The muscle descriptions and three-dimensional models provided in this study will facilitate further analysis of musculoskeletal adaptation and evolution within the Dasyuromorphia.

Escaping from predators is fundamental for the survival of any prey species. Australian fauna within the 'critical weight range' (CWR; 35 g-5.5 kg) are vulnerable to introduced eutherian predators. The absence of co-evolution between native marsupials and these novel predators may suggest that their antipredator behaviour towards the hunting strategies of these predators is inappropriate or ineffective. We quantified the escape behaviour of eight CWR marsupial taxa (three quadrupedal bandicoots and five bipedal macropods) to determine if differences in how they escape from predators indicate their ability to respond appropriately and effectively to introduced predators. Animals were filmed escaping through a runway and 20 measures relating to their gait, speed and path characteristics were recorded. These were reduced to four dimensions using multidimensional scaling (MDS): MDS1 linear speed versus agility, MDS2 acceleration style, MDS3 reactivity and MDS4 gait characteristics. We found a strong link between the phylogenetic relatedness of species and their use of linear speed or agility when fleeing (phylogenetic heritability, h(2) = 0.96). Bipedal macropod species used straight-line, fast escapes, which may be suited to escape pursuit predators. The quadrupedal bandicoots had an overall slower escape but were more likely to use sudden changes of direction, which can be successful if pursued by a larger, less mobile predator or where there is sufficient vegetation cover to obstruct pursuit. Repeated exposure increased linear speed (MDS1) and hastened the timing of acceleration (MDS2). The phylogenetic signal for escape speed/straightness suggests specific escape tactics may be constrained by morphology, although animals increased the intensity of their response after repeated exposure, suggesting training could enhance effective antipredator responses.

Digging animals perform many ecosystem functions, including soil turnover and vectoring fungi, particularly mycorrhizal fungi. However, these animals are also susceptible to the impacts of urbanisation, resulting in altered ecosystem processes. Some digging mammals, such as the omnivorous quenda (Isoodon fusciventer), a medium-sized marsupial bandicoot endemic to southwestern Australia, persist in urban landscapes and may play important roles as fungal vectors. This paper examines the fungal community in quenda scats from natural vegetation remnants within a fragmented urban landscape to ask: are quenda acting as vectors for a functionally diverse fungal community?; what fungal functional types are being vectored?; and does remnant size impact fungal species richness and composition vectored by quenda? We sequenced 53 scat samples collected from remnants and found that quenda disperse a functionally diverse fungal community, with 31% of the molecular operational taxonomic units (OTUs) putatively mycorrhizal. Fungal OTU richness was greatest in scats from smaller remnants due to higher mean relative abundance of saprotrophs, pathogens and yeasts. Fungal OTU richness of ectomycorrhizal fungi, critical for plant growth, were found at a higher abundance in larger remnants. Fungal composition was affected by remnant size, type and condition of vegetation, and soil type. Our results indicate that maintaining digging mammal populations within urban landscapes may assist with dispersal of fungi that facilitate fungal-plant interactions, contributing to ecosystem health. These results are important to understand the complex ecological implications of urbanisation, and how remaining mammals are critical in maintaining ecosystem processes within the urban land-use matrix.

Predator-protected populations of threatened fauna are important for species conservation, although these animals can quickly become predator naïve and can lack appropriate antipredator behaviour to enable them to persist once released. Controlled predator exposure can improve predator recognition and encourage avoidance behaviour, but little is known about the escape responses or fleeing behaviour of prey species. We compared the escape behaviour of a small marsupial, the burrowing bettong, Bettongia lesueur, between two fenced populations: one that had been purposely exposed to feral cats, Felis catus, while the other had been maintained without exotic predators. To quantify escape behaviour, bettongs were trapped and released into a temporary runway and a threatening stimulus was introduced to encourage them to flee. Measures relating to reactivity (escape initiation), escape speed and flight path (protean characteristics: agility, path irregularity and straightness) were recorded from video footage. Cat-exposed bettongs were significantly heavier than those from the cat-naïve population. We found a significant effect of the interaction of treatment (‘cat-exposed’ or ‘cat-naïve’) and body mass on overall escape behaviour. These differences were attributed to increased reactivity and escape speed in cat-exposed bettongs, but not protean characteristics of their flight path. Cat-exposed bettongs fled at an intensity where body size affected their escape performance (larger animals performed longer bounds and achieved faster speeds), while this body size effect was not evident for cat-naïve animals. This result suggests the cat-naïve animals were not as motivated to flee. Introducing low levels of predation pressure can successfully promote the development of antipredator behaviour through selection and/or individual learning, including a heightened escape response. Controlled predator exposure may be able to address some types of prey naïvety and lead to increased survival outside predator-free sanctuaries.

Context: Ecologists need robust and effective methods to quantify the diet of animals. However, assessing dietary composition can be challenging because most animals are seldom observed eating, especially when studying rare or cryptic species.

Aims: Morphological analysis of scats has been extensively used previously, and recent advances in the accessibility of DNA barcoding techniques have also made molecular approaches a viable alternative for diet analysis from scats. We compared the results from two methods of scat analysis, to trial the use of contemporary approaches in scat analysis.

Methods: In the present study, we used morphological analysis and DNA barcoding of matter in scats to catalogue the diet of a generalist omnivore, the greater bilby (Macrotis lagotis Thylacomyidae), in the West Kimberley. The composition and diversity of diet items, as well as the taxonomic identification level, were compared between methods.

Key results: Each method provided complimentary results; morphological analysis uncovered the type of matter consumed (e.g. root, seed) and relative proportion of the total undigested content, whereas DNA barcoding could assign such matter to a taxon. Even though dietary DNA could be extracted from only 38% of scats, DNA barcoding identified a greater diversity of taxa in scats than did morphological analyses. Barcoding could detect the presence of highly-digestible items such as cossid moths (Cossidae) and spiders (Araneae).

Conclusions: Morphological analysis was useful for quantifying relative abundance of diet categories; however, DNA barcoding detected a greater diversity of dietary items within scats. Despite the expense of DNA barcoding, the method can more accurately identify the taxa consumed, whereas morphology can greatly underestimate dietary species diversity. However, the technical requirements for performing DNA analysis make it expensive, while resource-limited field ecologists can generally perform morphological analysis with appropriate training.

Implications: Researchers and land managers will benefit from using both approaches in concert to gain a robust understanding of the local bilby diet. However, the cost and limitations of DNA barcoding (particularly when dealing with degraded DNA) mean that this approach should only be employed when the quality of the genetic material within samples is suitable. We recommend conducting exploratory analysis using morphological analysis (potentially in the field), with follow-up DNA barcoding to detect highly digestible items in fresh scats.

Mycorrhizal fungi serve important functions in Australian ecosystems by forming mutualistic symbioses with plants that facilitate water and nutrient uptake. Scat analyses have shown that southern brown bandicoots (Isoodon obesulus fusciventer; 'Quenda') regularly feed on fungi, including ectomycorrhizal (ECM) species. Many of these ECM species are hypogeous and rely on mycophagous animals such as quenda to disperse their spores. We explored the tripartite relationship between a keystone Mediterranean tree, its associated mycorrhizal fungi, and a mammalian disperser. Wild-collected quenda scats were used as a mycorrhizal inoculum to grow Eucalyptus gomphocephala from seeds under glasshouse conditions. Autoclaved scats were used as a negative-control and sporocarp tissue from Pisolithus and Scleroderma ectomycorrhizal species were mixed together as a positive-control inoculum. Seedlings were harvested at 10 weeks to assess seedling growth and early mycorrhizal colonization of roots by high-throughput DNA sequencing. Quenda scat successfully introduced fungi to seedlings, shown by a 56% overlap of fungal operational taxonomic units (OTUs) detected in the scats and roots grown in fresh scat inoculum. Scat-inoculated seedlings had richer root mycorrhiza fungal assemblages and a higher proportion of mycorrhizal taxa compared to negative- and positive-controls. However, no difference in shoot or root mass in these young seedlings could be attributed to root fungi assemblages at this early growth stage, possibly reflecting that the role of mycorrhizae in these early seedlings was parasitic, rather than facilitatory. Our study has shown that spores of mycorrhizal fungi from the quenda scat inoculum can successfully germinate and colonize seedling roots after passage through the quenda gut.

Bioturbation is an important ecosystem process, and the loss of native digging mammals due to introduced predators and habitat loss may have detrimental consequences for ecosystem health. The mycophagous woylie (Bettongia penicillata ogilbyi) was once widespread across the Australian continent and currently exists in a greatly reduced range, while the omnivorous quenda (Isoodon fusciventer), which once occurred across the southern part of Western Australia (WA), remains common in south west WA over a reduced range. Populations of these two digging marsupials are currently maintained within sanctuaries where they can reach high densities. To assess the influence these digging marsupials have on fungal assemblages, we investigated fungal root associations among seedlings of a key mycorrhizal forest canopy species, Corymbia calophylla, R. Br. K. D. Hill and L. A. S. Johnson. Seedlings were grown in soil collected from inside (heavily-dug soil) and outside (minimally-dug soil) two predator-proof sanctuaries. Our results showed that above-ground seedling biomass was significantly greater for seedlings grown in soil collected from inside the sanctuaries. There were no differences in the diversity or species richness of rhizosphere fungal communities isolated from these seedlings; however, the community composition was significantly different. This was most obvious for the predator-proof enclosure that had been in place for 20 years (Karakamia Sanctuary) compared with the more recently-installed Perup Sanctuary (fenced in 2010; 4 years before this study). At Karakamia, there were greater numbers of putatively hypogeous ectomycorrhizal fungi inside the enclosure and four times the number of operational taxonomic units of arbuscular mycorrhizal fungi outside the enclosure. The differences in fungal communities suggest that digging mammals play a pivotal role in ecosystem functioning by influencing the rhizosphere of this key forest canopy species, which has implications for maintaining the health and persistence of forests.

Here, we compare the efficiency and accuracy of remote sensing and plot-based methods for measuring vegetation cover for the understory and canopy of banksia woodland in an urban area of Western Australia. Methods compared were visual estimation, foliage cover computation from photographs, satellite imagery and aerial photographs. Observations and images from 1 m2, 100 m2 and 625 m2 quadrats measured cover of small plants, understory plants and trees respectively. Aerial photography and satellite imagery allowed the number, height and cover of trees to be estimated in 625 m2 and 1 ha plots. The accuracy of methods was compared using a 28 month time series commencing before and after an intense bushfire that removed all foliage cover. Directly comparable methods were in close agreement and in combination allowed plant recovery to be quantified in great detail. Visual estimation of cover in the field was time-consuming but necessary to measure the contribution of individual species. Visual estimates from 1 m2 downward photos allowed functional groups of plants to be measured. The number of green pixels selected manually in photographs confirmed that cover calculated from ground-based photographs using algorithms was accurate, except when cover was very low. We developed a new algorithm for computing cover from photographs that was accurate at low cover (Gperc). Canopy cover estimation by algorithm from upward photographs was subject to more errors, requiring exclusion of some images. Landsat satellite images allowed the impacts of severe drought and previous fires to be identified against a background of relatively consistent seasonal variations since 1988. Aerial photographs from 1953 onwards showed gradual recolonisation by banksia woodland trees over 60 years following tree felling. These methods provide a toolkit for monitoring vegetation recovery after disturbance and baseline data for monitoring banksia woodland. This toolkit should also be suitable for most other plant communities.