Research Note
CSIRO PUBLISHING
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Australian Mammalogy, 2010, 32, 76–77
Hybridisation between dingoes and domestic dogs: a comment on Jones (2009) A. S. Glen Department of Environment & Conservation and Invasive Animals Cooperative Research Centre, Dwellingup Research Centre, Banksiadale Road, Dwellingup, WA 6213, Australia. Email:
[email protected]
Abstract. The recent review by Jones (2009) presents a strong argument that Victoria’s wild dog population cannot reliably be categorised into dingoes (Canis lupus dingo), feral dogs (C. l. familiaris) and hybrids. This presents a problem in the light of the dingo’s recent listing as a threatened species in that state. Wildlife managers must come to grips with questions regarding the relative conservation value of ‘dingoes’ with varying degrees of domestic dog ancestry. This will require improved knowledge of the ecological function of wild dogs, as well as extensive research into public attitudes towards the animals. Additional keywords: conservation value, ecological function, introgression, social values.
Jones (2009) recently provided an insightful review of the extent of hybridisation between dingoes (Canis lupus dingo) and domestic dogs (C. l. familiaris) in Victoria. This is an issue of immediate concern in Victoria with the recent decision to list the dingo as a threatened species (Anon. 2007). The topic is also of national concern as introgression of genes from domestic dogs presents the greatest threat to the survival of pure-bred dingoes (Corbett 2001; Daniels and Corbett 2003). Conservation of the dingo is all the more topical because evidence increasingly suggests that the species can perform important ecological functions (e.g. Glen et al. 2007; Johnson et al. 2007; Letnic et al. 2009a, 2009b). However, the findings of Jones (2009) present a dilemma for dingo conservation in Victoria and nationally. Jones (2009) concludes that if pure dingoes still exist in Victoria’s eastern highlands, they cannot reliably be distinguished from other wild-living canids. Other recent studies concur that the introgression of domestic dog genes into dingo populations is extensive, if not complete (Daniels and Corbett 2003; Elledge et al. 2008). This leaves wildlife managers with a conundrum. If hybridisation is already extensive, management must address the following questions: (1) Do hybrids differ from pure dingoes in terms of their ecological function?, (2) Can pure dingoes be distinguished from hybrids or feral dogs in the field?, and (3) How does hybridisation affect the intrinsic value of the animals? The first two are scientific questions, but the third requires a value judgment that must be made by the Australian community. It is not my intention to try to answer these questions, but to provide some brief comments, which I hope will stimulate debate and help to guide future research. The effect of hybridisation on the ecological function of wild dogs is unknown, but has been identified as a high priority for Ó Australian Mammal Society 2010
research (Claridge and Hunt 2008). Spencer et al. (2008) report that hybridisation has caused a substantial increase in the average size of wild dogs in recent decades. This will have increased the metabolic demands of individual wild dogs (Spencer et al. 2008), but how will this change manifest itself at the population level? Do these animals kill larger prey? Does the population consume a greater biomass of prey, or are there simply fewer animals taking the same total biomass? Regardless of whether hybrids differ from pure dingoes in their ecological function, it may be more important to ask whether wild dogs in a given context are ecologically harmful, neutral or beneficial. This may vary from one time and place to another. Comparisons between wild dog populations with varying levels of dingo ancestry may help to inform management. Although identifying pure dingoes is problematic, the relative purity of different populations can be established by a variety of techniques (Elledge et al. 2008). However, ecological comparisons would also have to take into account confounding effects such as social disruption due to lethal control. Disruption of social structure caused by control programs may have a strong influence on the ecological function of wild dogs (Wallach et al. 2009). Ideally, research should focus on populations subject to minimal disturbance. The issue is further complicated by the suggestion that some morphological traits may have been altered before European settlement of Australia due to domestication of some dingoes by Aboriginal people (Gollan 1984). The intrinsic value of hybrids relative to pure dingoes may also be difficult to assess. While judgments will inevitably be subjective, an animal’s intrinsic value might conceivably be influenced by the relative proportions of dingo and domestic dog ancestry, and whether the animal conforms to expectations of 10.1071/AM09031
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Hybridisation in dingoes
Australian Mammalogy
what a pure dingo looks like. But how much deviation from the ideal should we tolerate before an animal is no longer considered to be a dingo? Given the listing of the dingo as a threatened species in Victoria, answers to these questions will be required as a matter of priority. I suggest widespread public consultation involving laypersons from urban and rural backgrounds as well as professional wildlife managers. The views of indigenous Australians should also be sought, as dingoes have cultural significance to many Aboriginal people (Breckwoldt 1988; Rose 2000). It is vital that efforts to conserve the dingo are informed by community values, as well as sound ecological understanding. Acknowledgements A. Glen is supported by a postdoctoral fellowship from the Invasive Animals Cooperative Research Centre. Sincere thanks to D. Sutherland and three anonymous referees for feedback on an earlier draft.
References Anon. (2007). Final Recommendation on Nomination Number 789, Canis lupus dingo. Scientific Advisory Committee, Department of Sustainability and Environment, Melbourne. Breckwoldt, R. (1988). ‘A Very Elegant Animal: The Dingo.’ (Angus and Robertson: Sydney.) Claridge, A. W., and Hunt, R. (2008). Evaluating the role of the dingo as a trophic regulator: additional practical suggestions. Ecological Management & Restoration 9, 116–119. doi: 10.1111/j.1442-8903.2008. 00402.x Corbett, L. (2001). The conservation status of the dingo Canis lupus dingo in Australia, with particular reference to New South Wales: threats to pure dingoes and potential solutions. In ‘A Symposium on the Dingo’. (Eds C. R. Dickman and D. Lunney.) pp. 10–19. (Royal Zoological Society of New South Wales: Sydney.) Daniels, M. J., and Corbett, L. K. (2003). Redefining introgressed protected mammals: when is a wildcat a wild cat and a dingo a wild dog? Wildlife Research 30, 213–218. doi: 10.1071/WR02045
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Elledge, A. E., Allen, L. R., Carlsson, B., Wilton, A. N., and Leung, L. K. (2008). An evaluation of genetic analyses, skull morphology and visual appearance for assessing dingo purity: implications for dingo conservation. Wildlife Research 35, 812–820. doi: 10.1071/WR07056 Glen, A. S., Dickman, C. R., Soulé, M. E., and Mackey, B. G. (2007). Evaluating the role of the dingo as a trophic regulator in Australian ecosystems. Austral Ecology 32, 492–501. doi: 10.1111/j.14429993.2007.01721.x Gollan, K. (1984). The Australian dingo: in the shadow of man. In ‘Vertebrate Zoogeography and Evolution in Australasia’. (Eds M. Archer and G. Clayton.) pp. 921–927. (Hesperian Press: Perth.) Johnson, C. N., Isaac, J. L., and Fisher, D. O. (2007). Rarity of a top predator triggers continent-wide collapse of mammal prey: dingoes and marsupials in Australia. Proceedings of the Royal Society of London. Series B. Biological Sciences 274, 341–346. doi: 10.1098/rspb.2006.3711 Jones, E. (2009). Hybridisation between the dingo, Canis lupus dingo, and the domestic dog, Canis lupus familiaris, in Victoria: a critical review. Australian Mammalogy 31, 1–7. doi: 10.1071/AM08102 Letnic, M., Crowther, M. S., and Koch, F. (2009a). Does a top-predator provide an endangered rodent with refuge from an invasive mesopredator? Animal Conservation 12, 302–312. doi: 10.1111/j.1469-1795.2009. 00250.x Letnic, M., Koch, F., Gordon, C., Crowther, M. S., and Dickman, C. R. (2009b). Keystone effects of an alien top-predator stem extinctions of native mammals. Proceedings of the Royal Society Series B: Biological Sciences 276, 3249–3256. doi: 10.1098/rspb.2009.0574 Rose, D. B. (2000). ‘Dingo Makes Us Human: Life and Land in an Australian Aboriginal Culture.’ (Cambridge University Press: Cambridge.) Spencer, R.-J., Lapidge, S. J., Dall, D., and Humphrys, S. (2008). Bringing out the mongrel in Australian dingoes: the evolution of wild dog body size. In ‘Proceedings of the 14th Australasian Vertebrate Pest Control Conference’. p. 149. (VPC: Darwin.). Wallach, A. D., Ritchie, E. G., Read, J., and O’Neill, A. J. (2009). More than mere numbers: the impact of lethal control on the social stability of a toporder predator. PLoS ONE 4, e6861. doi: 10.1371/journal.pone.0006861
Manuscript received 26 October 2009, accepted 19 November 2009
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