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Staff Information > Visiting Staff

DR KAREN FIRESTONE

| Research | Current Projects | Publications |

  1. Phylogeography and subspeciation in northern quolls
  2. Population genetics of spotted-tailed quolls
  3. Genetic effects of translocation programs
  4. Paternity analysis in spotted-tailed quolls
  5. Management units among Tasmanian eastern quoll populations
  6. Elucidating social structure and mating strategies of spotted-tailed quolls from latrines and faecal DNA
  7. Population genetics of New Guinean quolls
 
1) Phylogeography and subspeciation in northern quolls, Dasyurus hallucatus
 
Northern quolls once occurred throughout the northern third of the continent, but are now restricted to just six major hotspots and a number of smaller offshore islands. They were once categorised into four different subspecies (predator, hallucatus, nesoeus, and exilis) based on morphological differences and geographical location, but these are no longer referred to in the current literature or in management plans. The remaining sites are geographically isolated with little to no chance of gene flow. In addition, with the spread of cane toads into sensitive areas, northern quolls in the Northern Territory are facing major declines in population numbers and the population is crashing. To halt the decline, and prevent localised extinctions, the Northern Territory Parks and Wildlife Commission is undertaking translocations (benign introductions) to two offshore islands.
 
As a first step, in helping to manage these populations effectively, we need to know if subspecies or Evolutionarily Significant Units exist. This project aims at using genetic data to determine if there are distinct phylogeographical population divisions within northern quolls as an aid to management.
northern quoll
Northern quoll
(photo credit: Trevor Naughton)
 
 
2) Population genetics of spotted-tailed quolls, Dasyurus maculatus
 
Spotted-tailed quolls, also known as tiger quolls, are the largest of the native carnivorous marsupials on the mainland of Australia. They occupy an important ecological niche as top level predators and scavengers. Two subspecies of quolls have been recognised: D. maculatus gracilis from north Queensland and D. m. maculatus from the south east of the mainland and Tasmania. However, previous genetic work (Firestone et al. 2000) has shown that the true genetic split occurs between Tasmania and the rest of the mainland, indicating that there has been a long separation of the Tasmanian population from the rest of the mainland populations.
 
The conservation status of spotted-tailed quolls from the southeast of the mainland has recently been reviewed and they have been upgraded from vulnerable to endangered under the Environment Protection and Biodiversity Conservation Act.
spotted tail quoll
Spotted-tailed quoll
(photo credit: Bill Dowling)

This project continues on from earlier studies and examines a host of population genetics questions in relation to this species, including: assessing levels of diversity within populations and differentiation between populations, determining paternity assignment in a wild population, and assessing effective population size for long term conservation.
 
3) Genetic effects of translocation programs
 
Both western quolls (chuditch, Dasyurus geoffroii) and northern quolls (D. hallucatus) are being actively managed through translocation programs, but these programs have very different histories. Western quolls once occurred throughout arid Australia, but are now restricted to a small pocket of habitat in southwest Western Australia. Population numbers were estimated to have declined to 6000 individuals, before they were listed as Endangered. Western quolls have been the subject of a long standing recovery program conducted by the WA Department of Conservation and Land Management that began in the early 1990s. Quolls bred in captivity at Perth Zoo were reintroduced to sites where they formerly occurred on the mainland throughout the 1990s. In addition a fox control program using 1080 baiting was implemented as part of CALM's long standing Western Shield program. Due to the success of the captive breeding, reintroduction, and fox control programs, western quolls were downlisted to Vulnerable. Now, over 10 years down the track, we have the ability to assess the effectiveness of this translocation program using genetic techniques.
 
The main questions we are interested in answering are: What is the genetic diversity remaining within these translocated subpopulations? What is the effective population size of these subpopulations? Is there gene flow between these subpopulations? Do the subpopulations need 'top-up' animals to maintain diversity? If so, how many animals would be required?
 
In contrast, the translocation program for northern quolls is much more recent, but no less urgent. As cane toads are sweeping through sensitive areas in the Northern Territory, northern quoll populations have been drastically reduced. In some areas where they recently occurred in large numbers, northern quolls are no longer found. The Northern Territory Parks and Wildlife Commission began a translocation program for northern quolls in 2002. Approximately 65 animals were translocated to two offshore islands, in cooperation with local traditional owners, in a benign introduction program. One island, Astell Island, was burnt out soon after the quolls were introduced. The other island, Pobassoo Island remained unburnt. We will be tracking these populations over time to assess the effectiveness of the translocation, to assess effective population size, to build pedigrees, and to provide advice for effective on-ground management.
 
4) Paternity analysis in spotted-tailed quolls, Dasyurus maculatus
 
Is there multiple paternity in spotted-tailed quoll litters? Are bigger males better breeders? Some data suggests that multiple paternity exists in related Antechinus species, but we do not have this information for quolls. Also, traditional evolutionary theory of male-male competition and female mate choice might suggest that bigger males are better breeders, but again, we do not know if this is the case for quolls.
 
Spotted-tailed quolls are nocturnal, cryptic, and elusive predators and scavengers. Despite being the largest native mammalian predator remaining on the mainland of Australia, there are large gaps in our knowledge of the species. It is often difficult to obtain information for spotted-tailed quolls through traditional ecological methods such as mark and recapture or radiotracking studies, thus we have very limited information on the breeding and social structure of this species.
a litter of quolls
Litter of spotted-tailed quolls
(Photo credit: Sandra Anderson)

We aim to use the genetic technique of fingerprinting to assess paternity in a wild population of spotted-tailed quolls as a means of understanding the population structure in this species. To do this we have sampled a population near Dorrigo, NSW in conjunction with Al Glen (University of Sydney). To date we have a collection of samples from females and their pouch young and a yearly cohort of potential sires for paternity assessment.
 
5) Management units among Tasmanian eastern quoll populations, Dasyurus viverrinus
 
Eastern quolls once occurred on the mainland of Australia and in Tasmania; the last definitively known eastern quoll on the mainland was a road kill from Vaucluse in the eastern suburbs of Sydney in the early 1960s. This specimen is now housed at the Australian Museum. Eastern quolls are now thought to be extinct on the mainland but reported sightings of eastern quolls from the mainland still occur. However, this species does persist in Tasmania where they remain in relatively good numbers.
 
The recent and deliberate introduction of foxes and the outbreak of the Tasmanian devil facial tumour disease in Tasmania have cast doubt on the security of eastern quolls in this area. On the mainland, captive colonies of eastern quolls are maintained in a number of public and private institutions for breeding and display purposes. These animals, originating from Tasmanian stock, have been bred for a number of generations with little new genetic input since the founding of the captive population. These animals are now beginning to show signs of reduced reproductive output.
 
Recent genetic studies by Tasha Czarny (Monash Institute for Reproduction and Development) indicate that perhaps the captive population may have restricted genetic diversity. Continuing studies aim to look at the question of genetic diversity in the broader captive population from throughout the mainland.
 
In addition to maintaining captive populations, there have been proposals to reintroduce eastern quolls to the mainland of Australia, as an insurance policy for any catastrophic environmental events (such as the establishment of foxes or the cross-species transfer of disease from Tasmanian devils to quolls) and to reestablish native marsupial populations in former areas of their range. In order to do this effectively, we need to know which populations of eastern quolls in Tasmania are potential sources for reintroductions, i.e. which populations have retained high levels of diversity. This project aims at surveying eastern quolls throughout Tasmania to examine levels of diversity within populations and also to determine if distinct management units exist in eastern quolls. If populations are not significantly differentiated into discrete management units, one management scenario might be that we could found new mainland populations from animals taken from a variety of sites to increase diversity.
 
6) Elucidating social structure and mating strategies of spotted-tailed quolls from latrines and faecal DNA
 
One of the most interesting projects we are doing in association with Monica Ruibal (ANU), is focussed on using faecal material to understand the social structure and function of latrines.
 
The spotted-tailed quoll is considered to be a solitary and territorial animal, where social contact is largely restricted to the breeding season. However, to maintain spatial organisation and ensure reproductive success, an effective communication system is required. Among other mammals it is well established that urine, faeces and/or glandular secretions are used to mark specific objects or landmarks in the environment to chemically communicate information.
 
This chemical information can relate to age, individual identity, sexual identity, reproductive status, or communal belonging. It is thought that by leaving individualised messages, animals are able to demarcate their territorial boundaries, signal reproductive receptivity or identify areas with high quality resources.
quoll scat
Photo of a scat
(Photo credit: James Dawson)
 
Among populations of spotted-tailed quolls, aggregations of faecal droppings, known as latrines,can be found on prominent features in the landscape, such as on large rocky outcrops or flat boulders along creek lines. Trapping records suggest that young and adult individual of both sexes visit these areas, consequently it is thought that they function as communal defecation areas. This study is using non-invasive genetic techniques based on faecal DNA to elucidate if both sexes defecate at latrines, as well as identify the number of individuals using specific latrines. An important aim of this study is to distinguish the social significance of latrines; techniques being used include live-trapping, genotyping (from ear biopsies and faecal DNA) paternity analyses, information on spatial organisation, and temporal patterns of latrine use. Currently, over 70 latrine sites, identified by the Department of Environment and Conservation at Kosiuszko National Park, are being monitored on a regular basis.
 
7) Population genetics of New Guinean quolls
 
There are two species of quolls that occur in New Guinea, the bronze quoll (D. spartacus) and the New Guinea quoll (D. albopunctatus). The bronze quoll was only recently described as a new species; previously it was thought to be an extralimital population of western quolls. Very few records of bronze quoll exist in museum collections; it is only known from the Transfly region in southern New Guinea. The New Guinea quoll is also poorly known, although more records are available for this species. The New Guinea quoll appears to be centred on the central cordillera in the highlands of New Guinea and West Papua (Irian Jaya). Very little ecological information exists for either of these species.
 
Genetically, the only information we have is that the two New Guinean species of quolls appear to be most closely related to western quolls (Firestone 2000a). This relationship is not intuitive, given the distribution pattern of northern quolls. However, biogeographical patterns, shifting plates, and rising and falling sea levels could help to explain this relationship.
new guinea quoll
New Guinean quoll
(Photo credit: M. Mackay)
 
 
To our knowledge, this will be the first study to examine population genetics of any mammalian species in New Guinea.