Evolution of Stygofauna
Within the arid Yilgarn Region of Western Australia there exists an extraordinary and, until recently, unknown array of subterranean aquatic (stygofauna) and terrestrial (troglofauna) animals associated with calcrete (carbonate) aquifers.
We have recently shown that the calcrete aquifers are isolated systems, with extreme levels of species endemicity for aquatic beetles and crustaceans (Amphipoda, Isopoda and Bathynellacea).
The beetle fauna show a fascinating evolutionary pattern, with multiple calcretes containing 2-3 species in different size classes and cases of sympatric sister species, raising the possibility of their evolution by sympatric speciation. We are currently exploring this possibility and also studying the molecular evolution of genes involved in regressive evolution (e.g. loss of eyes) using the independently evolved subterranean beetles as a model system.
These calcrete ecosystems remain poorly understood; for example >80% of aquatic invertebrates are unidentified species and little is known about the dynamics of populations and their resilience to environmental perturbations. This limited knowledge of the fauna has become a significant issue for biodiversity conservation and the environmental review process for major resource projects, many of which rely on groundwater for their operations or carry out extensive dewatering or use calcrete as a resource. Further research on these aspects of the fauna are planned in future projects in collaboration with key researchers who are internationaly recognised for their contributions to groundwater biology.
- Investigators
- Steve Cooper
- Andrew Austin
- Michelle Guzik
- Rachael King
- Tessa Bradford
- Kym Abrams
- Collaborators & Partners
Our researchers have strong collaborative links with Bill Humphreys (Western Australian Museum), Peter Hancock, Remko Leijs
(Flinders University and South Australian Museum), Chris Watts (South Australian Museum), Stefano Taiti (Italy) and Joo-Lae Cho (South Korea).
(Flinders University and South Australian Museum), - Modes of Speciation in Subterranean Diving Beetles from Calcrete Aquifers of Central Western Australia
An investigation into modes of speciation in obligate subterranean invertebrates (stygofauna) from the Yilgarn region of central Western Australia. The aim is to determine if the sympatric beetles from a single aquifer are occupying separate trophic niches using new DNA 'barcoding' techniques (Bradford et. al, in press).
Further, to investigate any phylogeographic structure for three new amphipod species discovered within the calcrete. This project comprises Ms Tessa Bradford's PhD research.
- Systematics & Biogeography of Australian Subterranean Freshwater Parabathynellidae (Crustacea: Bathynellacea)
Parabathynellids have proven to be strikingly diverse in Western Australia, but are poorly known from other regions of Australia, despite having considerable scientific, conservation and economic significance. This project aims to taxonomically describe new parabathynellid species from various groundwater habitats in Australia.
In addition, molecular systematics will be used to develop a robust phylogeny and generic level classification to accommodate the new species described. This project comprises Ms Kym Abram's PhD research and preliminary results are published in Guzik et. al, 2008.
- Diversity, Evolution & Population Dynamics of Stygofauna from the Yilgarn Region of Central Western Australia
This project involves a large collaborative team of scientists who are studying the diversity and evolution of a recently discovered subterranean invertebrate fauna (stygofauna) found in numerous (>50) isolated calcrete aquifers in the Yilgarn region of central Western Australia. As part of this ARC Linkage grant, we are also developing rigorous sampling methods and studying the environmental variability within aquifers, based at a newly established field station at the Sturt Meadows pastoral property (Allford et al., 2008).
A further aim of this project is to investigate the population structure/dynamics of diving beetle species using microsatellite and mitochondrial DNA markers (Guzik et al., in review). Dr Michelle Guzik was employed on this project as an ARC research associate. These investigations have important implications for the sustainable management of the aquifers and the stygofauna within them.
- Systematics of Chiltoniidae (Amphipoda: Crustacea) in Mound Springs & Calcrete Aquifers of Western & South Australia
One of the most abundant invertebrate groups found in Australian mound springs and calcrete aquifers are the amphipods (Crustacea: Amphipoda). Of particular abundance are members of the family Chiltoniidae, represented by four species. Recent molecular analyses conducted by EES researchers have identified considerable genetic (mitochondrial DNA) diversity among discrete mound spring and aquifer populations.
We plan to utilize this population genetic framework to guide detailed morphological analyses on specimens from the collections of freshwater amphipod material held at the South Australian Museum and recent collections by researchers at the University of Adelaide.
Outcomes of the project will be: the description of many new amphipod species, the development of a Delta database to Australian Chiltoniidae, and an assessment of the systematics of the Chiltoniidae from Australia and overseas. The results will improve our knowledge of the biodiversity of arid zone groundwater ecosystems, which have significant conservation and economic value. Dr Rachael King is employed on this project.
- Exploration of a New Subterranean Terrestrial Ecosystem in the Arid Zone of Australia
In our field sampling of the stygofauna we discovered a diverse fauna of terrestrial subterranean species (troglobites) living in the air-filled voids of the calcretes. Higher taxa already known to be present include Palpigradi (an order new to Australia), Pseudoscorpionida, Isopoda, Schizomida, Meenoplidae (Homoptera: Fulgoroidea); Cossoninae? (Curculionidae: Coleoptera); Araneae (Gnaphosoids; Gallieniellidae?, Orsolobidae?).
Many, such as Palpigradi, are clear rainforest relicts providing a window into past climates and how aridity has shaped the Australian biota. However, to date we only have limited samples of the potential troglobitic diversity of this region. The current National Geographic project involves a survey of calcretes of the Raeside, Carey and Carnegie palaeodrainages using sampling techniques that are specific to troglofauna.
Taxonomic and molecular genetic analyses will be carried out to investigate the hypothesis that the calcretes form a subterranean archipelago for the troglobites in the same way as for stygobites, i.e., that each calcrete supports unique endemic troglobite species.