World’s first dingo genome sequenced shows it differs from that of domestic dogs
A new study has, for the first time, sequenced the genome of the Australian desert dingo, a wild dog geographically isolated from wolves and domestic dogs for thousands of years. Researchers, led by La Trobe University Professor Bill Ballard, showed that there are structural differences that separate the dingo’s genome from that of purebred dogs and that these changes have implications for the dingo’s physiology and even its gut microbiome.
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Dingoes play an important role in the Australian ecosystem. “Dingoes are Australia’s ‘top predator’, which means they influence everything in their environment,” Ballard explained in a press release.
Despite this, the origin of the dingoes remains unclear. Is the dingo essentially a wild dog or a distinct canid that has remained untamed? This debate fueled the current study, which analyzed a genome taken from a pure wild dingo – crossbreeding with a domestic dog created numerous dog-dingo hybrids – named Sandy. Funding to sequence Sandy’s genome only came after she won a competition to find the The most interesting genome in the world in 2017.
Sandy’s genome was assembled using a selection of techniques, producing a sequence 2.35 billion bases long. The genome was then compared to that of five dog breeds that represent the spectrum of domesticated canines: the German Shepherd, Boxer, Labrador, Basenji and Great Dane.
To create an evolutionary tree involving domestic dogs and the dingo requires a reference genome that is genetically different from the animals under study – this is called an outgroup. Here, the authors chose the Greenland wolf as an outgroup, a subspecies that predates Eurasian dogs and wolves and very rarely intermixes with other canid populations.
The analysis showed that the dingo’s genome, isolated from other canids in Australia, diverged from domestic dog breeds, showing up to 24 million unique bases compared to domestic breeds.
There were at least three major chromosomal differences noted between Sandy’s genome and that of reference dog genome, which is taken from a Boxer breed. A substantial difference, identified in a precedent study, was that the dingo’s genome had only one copy of a gene that codes for an enzyme in the pancreas called amylase. Domestic dogs have multiple copies of this gene, which functionally aids in starch digestion.
The authors wanted to explore whether such genomic differences would have any effects on canid physiology. They noted that some gene transcripts related to nutrient metabolism, such as that of GAL3ST1, were more strongly expressed in the dingo than in purebred dogs.
To test whether these changes would impact how canids metabolize food, they examined a group of 17 dingoes and 15 German Shepherd dogs (the breed with the most genomic similarity to the dingo) over a period of 15 days. Animals were treated with an antibiotic and then given a probiotic to minimize differences in their microbiome. They were then fed a similar diet for the duration of the experiment (two of the dingoes spiced up their palates by devouring an unfortunate opossum that fell into their enclosure during the experiment). This analysis confirmed that amylase was reduced in the dingoes at the end of the study and that their cholesterol and low-density lipoprotein levels were significantly higher. Microbiome analysis also suggested differences between domestic dogs and dingoes.
Ultimately, the authors concluded that their evidence suggests the dingo’s genome diverged “significantly” from this domestic dog, although they note that these canids all remained relatively similar when compared to the Greenland wolf.
Are dingoes responsible for the loss of livestock?
They also argue that genomic and metabolic differences between dingoes and domestic dogs could have implications for how dingoes are managed in Australia. Dingoes and wild dogs are considered synonyms in Australia, where they are also considered a threatens to cattle pasture. Ballard says their data implies dingoes instead evolved to eat native Australian species, such as marsupials and reptiles. “Based on this new knowledge, we hypothesize that dingoes are much less likely to eat farm animals, including sheep. If we are correct, what farmers currently assume are dingoes killing their cattle, are probably wild wild dogs,” Ballard said.
As dingoes are a top predator in Australia, Ballard suggests that overzealous control of dingoes could have major ramifications for Australian ecosystems: “If dingoes are not given the protection they deserve, it will upset the ecological balance. of the country, which could lead to environmental problems such as erosion and species extinction.
There are still unanswered questions about the dingo. The team calls for a more detailed analysis of pure dingoes in their ecosystem. But their research shows the power of genomics to unlock the mysteries of Earth’s most iconic animals. “This gives us a much clearer view of the evolution of the dingo – which is fascinating from a scientific perspective, but also opens up all sorts of new ways to monitor their health and ensure their long-term survival.” , concluded Ballard.
Reference: Field MA, Yadav S, Dudchenko O, et al. The Australian dingo is one of the first offspring of modern pedigree dogs. Science. Forward. 2022; 8. do: 10.1126/sciadv.abm5944