Fire and habitat management for a mycophagous marsupial, the Tasmanian bettong Bettongia gaimardi

The endangered Hastings River mouse (Pseudomys oralis) as a disperser of ectomycorrhizal fungi in eastern Australia

Rodents are the most widespread and diverse order of vertebrate mycophagists and are key to the dispersal of mycorrhizal fungi. Rodents consume and subsequently disperse fungi through their feces on every continent except Antarctica. This study examines the fungal taxa consumed by the Hastings River mouse (Pseudomys oralis), an endangered Australian endemic rodent from the family Muridae. We analyzed 251 fecal samples collected over a 19-year period between 1993 and 2012 at sites throughout the distribution of the animal in New South Wales and Queensland. We show that at least 16 genera of mycorrhizal fungi are eaten by this species and that it is therefore playing an important role as a vector of ectomycorrhizal truffle-like fungi in eastern Australia. Similar to the fungal diets of other mammals in eastern Australia, seasonal fungal consumption was greatest in autumn and winter. The dietary diversity of P. oralis also appeared to follow a geographic trend from south to north; samples collected at sites in the southern part of the species' range had greater diversity than those from sites in the northern part of the range, and overall, diets from southern sites yielded more fungal taxa than did northern sites. This study provides novel insights into the diet of P. oralis and highlights the importance of previously overlooked ecosystem services this species provides through its dispersal of mycorrhizal fungi.

Nitrogen content, amino acid composition and digestibility of fungi from a nutritional perspective in animal mycophagy

Fungi comprise a major part of the diet of many animals. Even so, the nutritional value of fungi has been much debated, with some arguing that fungi are nutritionally poor. However, the chemical composition of fungi and of the biology of the animals that eat them are not well understood, particularly in reference to amino acid (AA) composition of fungi and digestibility of fungal protein. We analysed fibre, total nitrogen (N), available N, and AA contents and measured in vitro digestibility of a wide range of epigeous and hypogeous fungi collected in Australia and the USA to test three hypotheses: (i) fungi are nutritionally poor because they contain few nutrients or are otherwise of low digestibility, (ii) fungi vary substantially in their nutritional composition; and (iii) animals can counter this variable quality by eating diverse taxa. Resultant data indicate many fungi are a reasonable source of AAs and digestible nitrogen. However, they vary highly between species in AA content, and the protein has a poor balance of digestible AAs. This helps explain why many mycophagous animals eat a wide array of fungi and often have digestive strategies to cope with fungi, such as foregut fermentation. Another common strategy is to supplement the diet with high quality protein, such as insect protein. Accordingly, evaluating nutritional value of fungi requires consideration of physiology of the animal species and their whole diet.

Fire-related changes in biomass of hypogeous sporocarps at foraging points used by a tropical mycophagous marsupial

Changes in pre- and post-fire biomass of hypogeous fungal sporocarps remaining at locations where an endangered mycophagous marsupial, the northern bettong (Bettongia tropica), had foraged, were assessed in fire-prone sclerophyll forest in northeastern Australia. Low to medium intensity experimental fires were set during the late dry season in 1995 and 1996 and post-foraging biomass of sporocarps (expressed as biomass of sporocarps remaining at recent B. tropica diggings) was measured at unburnt and burnt sites at approximately six-week intervals for a period of 14 months. Post-foraging biomass was significantly higher at burnt sites immediately following fire compared with control sites, solely due to increased biomass of hypogeous species belonging to the family Mesophelliaceae. Several months after fire, post-foraging biomass was significantly higher on unburnt sites compared with very low biomass on burnt sites. Twelve months after fire, the biomass on burnt and unburnt sites was not significantly different, having returned to biomass observed pre-fire. All evidence points toward mesophellioid fungi being greatly more available to bettongs on recently burnt ground, but fire may make several other sporocarp taxa considerably less available several months following fire.