There has been little research on the effect of hybridisation of closely related groups on the ability of the population to survive or the effect on its place in the local ecology. The best studied case is perhaps the red wolf which was a target for a concerted conservation effort until it was found to be a hybrid between the gray wolf and the coyote (Lehman et al, 1991). Hybridisation may cause genetic change in the population and, although there is strong strong social pressure to avoid it because of the damage it may cause, there are no long term studies on whether it would actually have an adverse effect. The dingo and the dog are quite different in behaviour and patterns of reproduction and it is possible that changes in hunting behaviour of hybrids and increase in the numbers of litters per year would adversely affect populations of other native species. However, whether hybridisation would have a long term effect on fertility or the survival of a wild canine population is not known. The production of markers to differentiate dog from dingo genetic material is a first step in a long term study of the effects of hybridisation. Without the ability to determine the extent of hybridisation such a study would not be possible. We are not proposing to do such a study here but only develop the tools to make it possible.

Dogs are useful vehicles for the study of genetic disease and thus gene function. Gene mapping in dogs to identify disease genes is in its infancy relative to many species. Maps of highly polymorphic mcrosatellite loci are under construction (Lingaas et al, 1997) but these contain no information on functional genes. The location of blocks of genes on these maps would make these more useful for disease gene identification and gene cloning. The high conservation of syntenic groups of genes among mammals makes this possible by localising a small number of genes. However polymorphisms are required to place genes on the map. It is often difficult to find variation in a functional gene within a species but crosses between related species that produce fertile offspring are often extremely useful because accumulation of genetic differences often produces fixed differences at large numbers of loci. Hybrids will be heterozygous at these loci and data from offspring out of backcrosses to either parent can be used to map the functional genes. This has been successfully applied to mapping genes in tammar wallaby (McKenzie et al, 1993). We intend to identify markers useful for localising functional genes by examining differences between dingoes and dogs at intronic sequences of conserved genes.

Background:

Dingoes are a type of Asian dog which is possibly derived from the Indian or Arabian wolf by domestication not more than 10,000 year before present (Corbett, 1995, Ch1). They have been spread throughout South-East Asia and the Pacific by man. They first arrived in Australia less than 5,000 BP.
Although they have many distinct physical and behavioural characteristics that differentiate them from domestic dogs, such as an annual breeding cycle, the two species interbreed and produce fertile offspring as do many wolf-like species.
Western influences have lead to the introduction of domestic dogs throughout the dingoes range. The proportion of pure dingoes in the wild canid populations is steadily decreasing with large proportions (>80%) known only in Thailand and Australia (Corbett, 1995, Ch10). Within Australia hybridisation occurs most readily in highly populated areas with populations from the East coast and South-East and South-West containing mostly hybrids. The more isolated central and Northern areas have the largest proportions of pure dingoes but with increasing numbers of domestic dogs on properties and in aboriginal camps, the dingo is under threat in even these areas.
If the dingo is to be preserved as a native animal, a conservation program needs to be undertaken. Public education is probably the best way to reduce the numbers of dogs available for hybridisation in the wild and several groups are working towards this. Captive breeding programs are the best way to ensure the long-term future of the Australian dingo and zoos, wild-life parks and dingo associations are undertaking this. However, how can the genetic purity of the breeding stock be assured? Many animals in captivity come from South-East Australia where the proportion of pure dingoes is estimated to be as little as 22% in one population with a maximum of 65% (Corbett, 1995, p166, ).

The Australian dingo (Canis lupus dingo) is recognised as a subspecies of the wolf-like canids. It is biologically distinct from dogs with differences in reproduction (dingoes breed only once a year), coat colour, and other physical and physiological characters (Corbett, Ch3). To allow the dingo to disappear due to interference from modern society would be unethical. This is recognised by the many groups who have established captive breeding programs, such as the Australian Native Dog Conservation Society and the Australian Dingo Conservation Association. In some areas of Australia dingoes are being housed with families and kept as pets. The dingo is currently a recognised dog breed and is being bought and sold.