In this section
- Modelling invasive European rabbit distribution in Australia
Recent research supported by the Foundation for Rabbit-Free Australia include:
Previous research, supported in part by RFA, sequenced DNA from rabbits around the country and found that they form 6 genetic clusters, indicating there were multiple introduction events during European colonisation. In this project, Amy Iannella investigated which genetic loci differentiated those clusters, and whether those differences are connected to genes that could cause varied susceptibility of rabbits to RHDV.
The investigation discovered one candidate RHDV resistance gene, differentiated based on rabbit ancestry. The differentiating gene, called MHC class 1, is a major immune gene which could also impact resistance to other infectious diseases such as myxomatosis. The most common MHC class 1 variant in Western Australia and South Australia appears to differ from that of the eastern states.
The methods developed in this study will allow rapid testing for geographic differentiation of any newly identified resistance genes as other studies across the globe continue to uncover the genetic causes of RHDV resistance.
The project method was:
- Run all available rabbit sequence data through the analysis pipeline from Iannella 2018 to characterise the genetic markers for each cluster.
- Use four independent software packages (Bayescan, fsthet, Arlequin and FLK) to find genetic markers that differentiate rabbit clusters. Create a list of consensus markers from these software.
- Identify genes in close proximity (within 40kb) to the consensus markers following Schwensow 2017’s methods.
- Compare the identified genes to those identified by Schwensow 2017 as correlating with RHDV survival.
- Document results as a manuscript for scientific publication, and as an article for public communication.
For more information, see:
- Summary Article – Should we care that rabbit genes are different around Australia?
University of Adelaide PhD student, Emilie Roy-Dufresne, was assisted by RFA in a project to model the distribution and population dynamics of wild European rabbits in Australia. The work included mapping the potential invasion range of wild rabbits in Australia, testing how model predictions change when micro-habitats are considered, and developing a pest management modelling framework for wild European rabbits that accounts for varying demographic rates, habitat suitability, dispersal processes, and density-dependent processes.
RFA assisted with funds for training in statistics and Bayesian modelling, and attendance at an international scientific conference. Emilie was subsequently a contributor to a paper by Brown et.al. ‘Models of spatio-temporal variation in rabbit abundance reveal management hotspots for an invasive species‘, published in EcoEvoRxiv Preprints.
Flinders University research associate, Dr. Louise Barnett, was helped by RFA to better understand how the myxomatosis and RHD viruses interact. Eighteen years of mark-recapture, dead recovery, and antibody assay data from Turretfield (SA) has been used to model the impact of myxoma and RHD on the survival of rabbits with different exposure histories – indicating that rabbits previously exposed to myxoma are more susceptible to RHDV. That information suggests that new pathogens could reduce rabbit survival by a substantially greater margin than their individual effects measured in isolation from other pathogens.
RFA funding helped Louise with model enhancement to enable the potential impact of new pathogens to be better predicted. A paper submitted to the Journal of Applied Ecology presents findings from this research and a ‘progress report’ presentation, ‘Using the Turretfield rabbit population to assess the impact of myxomatosis and rabbit haemorrhagic disease‘, was given at a RFA Annual General Meeting.
It is now accepted that flies are a major vector for the transmission of RHDV. Thanks in part to former RFA funding, research also showed that flies could be used as an easier way to measure the spread of the virus within rabbit populations compared to relying on rabbit carcasses – but an efficient sampling and analysis were not available.
Dr Adam Croxford, at the University of Adelaide, used RFA and PIRSA funding to investigate a method for optimum extraction of RHDV viral RNA from bulk samples of flies, seeking a better sampling option to make it easier to monitor and understand the spread and interactions between various forms of RHDV, resulting in better rabbit control programs. The work helped develop freeze drying and bulk analysis processes and contributed to a method now employed nationally by CSIRO.
The Koonamore vegetation monitoring reserve shows rabbit control is essential for the regeneration of many tree and shrub seedlings – and a donation from RFA helped with re-fencing. Thanks to funding support from RFA and others, Koonamore – the longest running vegetation monitoring project in Australia – has been able to upgrade part of the reserve’s rabbit-proof boundary fencing.
Officially titled the TGB Osborn Vegetation Reserve, Koonamore Station, the 4km square reserve is managed by the University of Adelaide and an enthusiastic team of volunteers, lecturers past and present, and students. The site is used by students and researchers from both Adelaide and Flinders universities.
For more information, see ’90 Years of Change. The TGB Osborn Vegetation Reserve, Koonamore’, or search for ‘Koonamore’ videos of photopoint sequences on Youtube.
A RFA supported PhD scholarship (Amy Ianella) mapped out the family trees of rabbits to see if genetics were behind an apparent increase in resistance, or whether it was more due to seasonal factors like the abundance of insect vectors and the innate resistance of very young rabbits (who, if infected, retain that immunity for life). The study found that a small number of older rabbits were disproportionately responsible for the majority of surviving offspring, indicating a genetic factor at play. However, seasonal factors also affected survival rates, probably through a combination of feed availability and seasonal disease outbreaks.
- A contribution to the ‘RHD Boost’ project, through the Invasive Animals CRC, to evaluate possible new strains of RHD for Australia and to prepare for their release.
- A Postgraduate Research Grant awarded to Maija Marsh whose research project was titled ‘Causes of local variation in the impact of RHDV on rabbit populations’. This grant supported a visit by Dr Piran White from the University of York, UK, to provide assistance with fieldwork, collaborate more closely with Maija and other Australian researchers, and to develop further joint research topics on RHDV dynamics and rabbit control. Extra funding was also provided to enable Dr. White and Maija Marsh to travel to Adelaide and give a seminar to RFA members.
- Two small research grants provided through the Royal Zoological Society’s scholarship scheme.
- Support for Dr. Katherine Moseby, Roxby Downs, to extend information from a rabbit control project, involving the radio-tracking of rabbits to understand their behaviour – such as time spent in burrows and grazing. It showed that home ranges were larger in winter than summer.
- Josh Griffiths, The University of Adelaide, with logistic support for a project on competition between rabbits and bilbies. It involved radio-tracking bilbies in the wild at Venus Bay and at Roxby Downs, and showed that males roamed much further than females – covering up to several kilometres in an evening.
- A travel grant to allow Greg Mutze, Senior Research Officer from the then Animal and Plant Control Commission, to attend the 2nd International Lagomorph Conference in Portugal, and to consult with scientists at an RHD laboratory in Italy. S Kidman & Co provided additional funding through RFA.
- A Rabbit Calicivirus Research Project, co-funded with S Kidman & Co.
- The Chair of RFA chaired the RHDV K5 Operations Working Group supporting research to boost the impact of RHD, especially in cooler, wetter regions of Australia. The ‘Boost’ project evaluated different strains before identifying a South Korean variant (K5) as being most prospective. The Working Group brought key stakeholders together to assist in managing the release of the K5 variant across Australia’s rabbit infested lands.
- Convening a National Workshop on Rabbit R&D Directions in 2005, which stimulated Meat & Livestock Australia and Australian Wool Innovation to develop a grazing industry strategy for rabbit management and abatement. RFA’s predecessor had convened a major conference in 1993, which was important in garnering support for research into, and the release of, the RHD virus.
- Membership of the National Rabbit Management Advisory Group, a body jointly funded by Australian Wool Innovation and Meat & Livestock Australia and convened by the Invasive Animals Cooperative Research Centre, to provide national strategic and practical advice on the planning, implementation and delivery of rabbit research and development programs and their outcomes.
- Supporting the establishment of the Invasive Animals CRC with letters of support and contact with government agencies and Ministers.
- Sponsoring a rabbit session at the 2008 Australian Vertebrate Pests Conference, and a 2007 seminar on the impact of RHD.
- Contributing to a CSIRO Division of Sustainable Resources ‘Rabbit Conference’, in 2001.