Project 4 - Small Terrestrial Vertebrates: Clarifying Taxonomic StatusThe true diversity of many groups of Australia's mammals, reptiles and frogs is seriously underestimated by the current taxonomy which is still based largely on traditional, morphological assessments. Our goal is to promote a more systematic approach to the discovery of Australian vertebrate diversity through the combined use of molecular and morphological methods, with case studies selected across a range of different groups.
Challenges
Vertebrates such as mammals, frogs and reptiles are often thought to be taxonomically well known, with little need for further scientific collecting or taxonomic research. In Australia, this perception has been shattered over the last two decades by the discovery of high levels of genetic diversity in many widespread vertebrate species. Careful study of these groups almost always shows them to comprise multiple, partially overlapping species, often with contrasting ecologies and conservation status. Vertebrate diversity in Australia clearly is much higher than we currently think... but what groups are most seriously affected? And what are the best strategies and methods for documenting the hidden diversity?
The urgency of the problem is heightened for Australian mammals by the fact that many species are now very restricted in range due to the massive declines that occurred during the 19th and 20th centuries. For many of these species, we know little about their original geographic distribution and habitat preferences, and even less about the original pattern of genetic variation. Today, these gaps in knowledge hinder management of the surviving populations, and they also impede a growing interest in reintroduction programs as a way of rebuilding ecological communities and ensuring individual species survival. With the inevitability of further loss of small, isolated populations through random processes, the growing likelihood of climate change impacts, and the evidence of more general ongoing declines in the mammal fauna of northern Australia, there is real possibility that Australian mammals will experience a second wave of extinctions. This is a scenario that cannot be ignored.
Seeking solutions
All of our work uses a combination of molecular and morphological approaches to understand taxonomic diversity. Our focus is on adequate and effective approaches that lead to taxonomic resolution, and each project generally employs a slightly different set of methods or a different balance between morphology and molecules. For many of the projects, the study materials include historic and/or prehistoric specimens and these require special methods to extract and amplify the degraded 'ancient' DNA.
Benefits
The project will highlight the incomplete state of knowledge of Australia's unique and vulnerable vertebrate fauna, and provide case studies that illustrate how modern taxonomic approaches can lead to rapid improvements in knowledge and to improved decision making and management.
Project progress
March 2010
Publication
Taxonomic re-assessment of the Australian and New Guinean green-eyed treefrogs Litoria eucnemis, L. genimaculata and L. serrata (Anura: Hylidae) ZooTaxa 2391: 33-46 (2010) [available by request only from Stephen Donnellan]
Novemeber 2009
Fieldwork
Further fieldwork was undertaken to collect bone deposits of great significance in three biogeographic regions. A collection of abundant well preserved bones of numerous small mammals from sites on the Liverpool Plains, the site of some of the earliest zoological collecting outside of the early settlements, recovered some species that were not documented historically and beautifully preserved skulls of some of Australia’s rarest small mammals.
Molecular data
The project continued to build morphometric and genetic datasets (including both modern and ancient DNA sequences). Ancient DNA extraction procedures have been refined to the point where recovery of good sequence data from museum specimens and cave specimens has become routine. Among the more exciting developments from this work are:
- Final clarification of the identity of the cryptic Melomys-like rodents from the wet tropics, now determined to be a new genus and species. The taxon was first detected during a population genetics project in 1996. We have tracked material in the Queensland Museum, and produced the critical ancient DNA sequences to link the historical voucher specimens to DNA sequences produced from ear clip samples.
- Recognition that the Feathertail Glider genus Acrobates is not monotypic but includes at least 2 species which occur together over broad areas (including around Sydney). No one has previously suspected that this genus consisted of more than one species. A critical issue now is the identity of the specimens used in the original description which dates to 1796. Remarkably, these specimens are still housed in the Natural History Museum, London. Another issue is which of the two species was featured on the now withdrawn Australian 1 cent coin! Project member Aplin will visit London in May to determine the identity of the original specimens.
- A successful study by associated University of Adelaide PhD student Vicki Thomson of the original genetic structure of the Hastings River Rat, a species that has disappeared across most of its original geographic range.
Publications and reports
This period saw publication of several taxonomic and biogeographic manuscripts and the preparation of additional manuscripts on taxonomic and conservation issues. A report on the taxonomy of Christmas Island Pipistrelle, a highly endangered (and possibly now extinct!) bat, was submitted to DEWHA. This was authored by collaborator Kris Helgen of the Smithsonian Institution with major input from project members Donnellan and Armstrong. Two reptile and one amphibian sub-projects were published in Zootaxa during this period. All of these studies illustrate the power of the integrated, iterative approach to resolving the most difficult vertebrate taxonomic problems, using both morphological assessments and the selective use of DNA sequencing and allozyme electrophoresis. Published works are:
- Taxonomic revision of the Carlia longipes group (project member Donnellan with collaborator P. Couper) published in Zootaxa (2009) vol. 2227:1-31. [available by request only from Stephen Donnellan]
- Generic revision of Eremiascincus, and description of a new species from the Pilbara (Donnellan with collaborator P. Doughty and international collaborator Sven Mecke) published in Zootaxa (2009) vol 2246:1-20. [pdf]
- Taxonomic revision of the green-eyed frogs of Australia and New Guinea including revival of a species found only in the Queensland Wet Tropics (Donnellan with various collaborators) published in Zootaxa (2009) vol 2291:33-46.
Web products
The key to the rodents of Australia (native and introduced) is under development and will cover the whole of Australia to include approximately 79 species. The key is comprehensive, yet structured to be easily expanded to all mammals. High level diagnostics will be included to make sure people really are looking at a rodent (i.e. not a marsupial). Anyone from a learner to a museum curator should find it useful.
There will be a trial of the field modules at the user product–testing workshop to be held in Townsville in April 2010.
Design of a web-deliverable database for sub-fossil bone assemblages was completed in this period, and population of the database has started.
Other news
Project member Ford made an important contribution to planning activities for fauna reintroduction in the ACT.
One of the key developments during this period was the acquisition by the ANWC of a Skyscan MicroCT which will greatly accelerate the rate of morphometric and anatomical data collection for mammals, reptiles and frogs. Utilization of micro-CT technology will:
- produce highly accurate anatomical and 3-D morphometric datasets on groups of vertebrates that previously were intractable due to their small size (eg legless lizards, blind snakes fossorial skinks)
- commence the task of generating a micro-CT image library of type specimens of Australian reptiles (scalation and cranio-dental anatomy) and mammals (cranio-dental anatomy).
Use of micro-CT technology is set to revolutionize how vertebrate taxonomy is done in Australia and overseas. Approval is being sought to scan holotypes held overseas, which will make an even greater contribution to our capacity for rapid progress in Australian vertebrate taxonomy.
September 2009
Poster: Taxonomic tools empower management, survey and conservation of small terrestrial mammals [pdf]
