Project 4 - Small Terrestrial Vertebrates: Clarifying Taxonomic Status

4.3: Taxonomy of northern Australian small terrestrial vertebrates

Challenges

Northern Australia is in many respects our biological 'frontier'. Although some early collections were made around colonial outposts, biological assessment of this area did not begin in earnest until the 1960s. Even today, many areas remain remote and inaccessible, and there are major geographic gaps in every kind of biological collection. The significance of this patchy and incomplete biological knowledge is further heightened by the following factors:

1. Australia's monsoonal tropics harbour exceptional local biodiversity coupled with a particularly strong regional endemism. This is centred primarily on the Pilbara Uplands, the Kimberley, Arnhem Land, and the various tablelands and ranges of Cape York Peninsula, but with a further layer of intraregional endemism in each case.
2. Many of the animals living in this landscape are ecologically cryptic (i.e. they remain hidden for much of the time to avoid extremes of heat, either by living in rock piles, cracking clays etc). For many groups, return for collecting effort is much lower than in other regions of Australia.
3. Many of the unsurveyed regions remain geographically remote and the fieldwork needed to improve collections is logistically and physically challenging. Additionally, very few plant and animal taxonomists are based in northern Australia hence fieldwork is costly and cannot be undertaken on a casual basis.
4. There is a growing perception that populations of many species of small vertebrates (especially mammals and birds) are experiencing broad scale, ongoing declines, for reasons that are not immediately obvious.
5. Northern Australia is attracting increasing attention as a focus for future developments in the resource sector, and as a possible food bowl for Australia under climate change scenarios. Accordingly, human population and impacts might be expected to increase markedly in coming decades.

Seeking solutions

We will undertake taxonomic studies of several groups of mammals, reptiles and frogs that have extensive distributions across northern Australia. Our work will be based primarily on existing collections but may lead to new field collecting if the results identify any critical gaps in available specimens. For mammals, the primary targets are a small carnivorous marsupial Planigale maculata, a small native mouse Pseudomys delicatula, and the mosaic-tailed rats of the genus Melomys. For reptiles and amphibians, the main targets are litter-dwelling skinks of the Menetia greyii/maini complex and Carlia longipes group, and the small ground frog Crinia riparia.

Approaches

For each group we will use an iterative approach that begins with initial screening of mtDNA haplotypes from all available samples of the target groups. Patterns of genetic diversity are then compared with patterns of morphological differentiation, and further molecular investigations carried out (e.g. nuclear gene sequencing, microsats, allozyme electrophoresis), as appropriate to each case.

For the mammal projects, taxonomic decisions will very likely require extraction and sequencing of DNA from historically collected individuals including some type specimens.

Collaboration

The work on Planigale is part of an ongoing collaboration with Dr Mark Blacket (University Melbourne) and Dr John Woinarski (NT NRETAS); work on Pseudomys delicatulus with Prof Bill Breed (University of Adelaide), work on Melomys with Dr Susan Fuller (QUT) and Ms Litticia Bryant (PhD student, QUT). Collaborators on the reptile and frog projects include Mark Adams and Dr Mark Hutchinson (both SA Museum), Dr Paul Doughty (Western Australian Museum) and Dr Patrick Couper (Queensland Museum).

Tools for Decision Makers

The work will lead to significant new insights into the geographic patterning of evolutionary diversity across northern Australia. The primary means of communication will be through taxonomic publications but results of this work will be made more accessible through provision of web-based resources including interactive keys.