Swamp wallaby: keystone mycophagist in a fragmented landscape?

A project undertaken at the School of Environmental and Rural Science, University of New England, supervised by Dr Karl Vernes

In north-eastern New South Wales the swamp wallaby is a wide-ranging habitat generalist that is tolerant of disturbance. Research done by us prior to this grant indicated that the swamp wallaby may be a keystone species in fragmented forested ecosystems because of its mycophagous diet and it’s resilience in these landscapes. The species is particularly important in the region due to the loss of most other mycophagous mammals since European settlement. Furthermore, in spite of the importance of truffle-forming fungi in forested habitats, little is known about mechanisms of spore dispersal for these fungi in fragmented landscapes.

This project aimed to simultaneously collect detailed taxonomic data for truffles and diet and dispersal patterns of a generalist mycophagist mammal to elucidate the complexity of mammal-fungal interactions, contribute significantly to knowledge of truffle diversity and inform management of natural resources in the region. Specific questions were:

  • How does the diversity of truffle fungi consumed by swamp wallabies compare across different habitat types in eastern Australia?
  • How does fungal consumption by swamp wallabies change seasonally?
  • How do population densities and movement patterns of swamp wallabies between forest fragments relate to dispersal of fungi in the landscape?
  • Does consumption of fungi by swamp wallabies increase the likelihood of fungal spore germination?

We completed a large landscape-scale study of fungal consumption and dispersal by swamp wallabies, and the most comprehensive study of truffle communities in northeastern New South Wales.  Our work:

  • Demonstrated that swamp wallabies are regular consumers and dispersers of a diversity of fungal spores, and are probably important in sustaining a diverse macrofungal community in their forested habitats
  • Provided a unique insight into the diversity of fungi that occur within eucalypt woodlands and forests, and provided much-needed data on a resource base that supports a suite of mammals that depend on truffles as a food resource.  Our work revealed the occurrence of over 118 truffle-like species in 35 genera in Eucalyptus forests of the Mt Kaputar and New England regions of north-eastern NSW.  Over half (61.9%) of the species were new to science, and more than 20 of these were described during the project
  • Was the first study of digesta passage rate in the swamp wallaby, and the first to use macrofungal spores as a marker to assess gut-retention time.  It was also one of only a few studies to determine gut-retention time for animals kept under semi-natural conditions
  • Using GPS tracking technology and spore passage rates (above), we developed a novel and powerful mathematical model of macrofungal spore dispersal by the swamp wallaby.

The truffle-forming fungi of Australia, although poorly known, are highly endemic and extraordinarily diverse, with some 300 species described and another estimated 800-1200 yet to be discovered. Our research shows that truffle diversity in the study area is likely to exceed 200 species and has already revealed taxa new to science. Difficulties with accurate identification of fungal spores in mammal diets has hampered studies of mammal mycophagy and limited accumulation and sharing of knowledge. A major impediment is the lack of an accessible, additive, central database (data currently scattered in disparate researcher and organizational datasets, collections and student theses) to advance information sharing and collaborative research across disciplines.

Accordingly, a second major aim of our work was to develop an online database to facilitate accurate identification of fungal spores and taxa, standardisation of methods, and provision of study site information, so as to increase potential for comparisons between studies and encourage collaboration and information sharing.  A new truffle and mycophagy organizational database, christened ‘TruffMO’, was developed, and populated with our mammal diet and truffle datasets.

‘TruffMO’ is a major innovation in the cataloging of data from truffle diversity and mammal mycophagy studies.  When fully functional and populated by a diversity of datasets from Australia and abroad, we envisage this database will become the primary resource for truffle mycologists and mammalogists working on mammal-fungal interactions.  TruffMO wil go online from March 2012.  Questions regarding access and use of this database should be directed to Karl Vernes (kvernes@une.edu.au).

Publications


Danks, M.A. (2011).  The swamp wallaby Wallabia bicolor: a generalist browser as a key mycophagist.  PhD thesis, University of New England.  262 pages.

Vernes, K. and Lebel, T. (2011). Truffle consumption by New Guinea forest wallabies.  Fungal Ecology 4: 270-276.

Danks, M.A. (in press). Gut-retention time in mycophagous mammals: a review and a study of  truffle-like fungal spore retention in the swamp wallaby. Fungal Ecology doi: 10.1016/j.funeco. 2011.08.005

Castellano, M.A., Trappe, J.M. and Vernes, K. (2011). Australian species of Elaphomyces (Elaphomycetaceae, Eurotiales, Ascomycota).  Australian Systematic Botany 24: 32–57.

Danks, M., Lebel, T., Vernes, K. (2010) ‘Cort short on a mountaintop’ - Eight new species of sequestrate Cortinarius from sub-alpine Australia and affinities to sections within the genus. Persoonia 24: 106–126.

Vernes, K. (2010). ‘Mycophagy in a community of macropodoid species”. Pages 155-169 In: ‘Macropods: the biology of kangaroos, wallabies and rat-kangaroos’ (Edited by G.M. Coulson and M.D.B. Eldridge) CSIRO Publishing, Melbourne.  424 pages.

Conference Presentations:

Danks, M. and Vernes, K., Andrew, N. and Lebel, T.  (2011).  “Swamp wallaby mycophagy in eucalyptus forests: patterns in richness and composition”.  91st Annual Meeting of The American Society of Mammalogists.  Portland State University 24–28 June 2011, Portland (Oregon, USA).

Vernes, K. and Lebel, T. (2010). First evidence of truffle consumption by New Guinea forest wallabies (Dorcopsis, Dorcopsulus and Thylogale)”. 56th Australian Mammal Society Meeting, Australian Academy of Sciences, Canberra. July 2010 [spoken paper].

Danks, M. and Vernes, K., Andrew, N. and Lebel, T.  (2009).  Mean retention time of truffle spores in the swamp wallaby digestive system.  Australian Mammal Society 55th Annual Conference, Perth, July 2009. [Poster]  This poster was voted runner-up best poster by a student at this conference.

Danks, M. and Vernes, K. (2008). "The swamp wallaby, Wallabia bicolor, as a keystone mycophagist in the variegated landscape of the New England Tableland, New South Wales". Australian Mammal Society 54th Scientific Meeting, Darwin, 29th September - 1st October.

Danks, M. and Vernes, K. (2008). "Swamp wallaby: keystone mycophagist in a variegated landscape". Ecological Society of Australia Annual Conference, Sydney, 1st - 6th December.

 
Figure 1.Swamp wallaby, Wallabia bicolor

Figure 2. Examples of some commonly-detected truffle-like fungi

Figure 3. Truffle spores in swamp wallaby faecal sample

Figure 4. Examples of spores of the most commonly detected spore taxa in swamp wallaby diet. (a, b) Agariceae 4; (c, d) Chamonixia; (e, f) Cortinarius 10; (g) Cortinarius 15; (h, i) russuloid 1; (j) Cortinariaceae 4; (k, l) russuloid 6; (m, n) Octaviania 2 / Hydnangium. Bar scale for all images 5 μm.

Figure 5. Swamp wallaby captured on camera trap at the edge of a forest fragment

Figure 6. Eight new species of Cortinarius  described as part of our project

Figure 7. Scanning electron micrographs of spores of one of the new Cortinarius species