The dingo ate our domestication

Below I mentioned the preprint, Genomic analysis of dingoes identifies genomic regions under reversible selection during domestication and feralization. I do think that readers will be quite interested in reading it, and it’s not too technical. As the authors note, the dingo is interesting because of the longest lasting “feral” lineage that is known. Additionally, unlike other feral lineages hybridization with other populations has been pretty minimal until recently (though they detected some in two of their dingo samples).

The phylogenetics isn’t that surprising. Dingos are closest to New Guinea Singing Dogs (NGSD). And this clade is most similar to Indonesian dogs. Basically, as you’d expect dingos are the product of a serial founder event from Southeast Asia into Australia. Their ancestral population is really, really, small.

The authors quote a time of arrival of the dingos to ~3,500 years ago, and their phylogenetic inferences seem to indicate divergence from Indonesian lineages ~5,000 years ago. That divergence is probably sensitive to some parameter estimates. But, it does make me wonder who the domestic dogs came with. Since they seem to be descended from Eurasian wolves, the most likely candidate is the first Austro-Asiatic farmers. From them, dogs could spread rapidly through feralization to neighboring populations of hunter-gatherers.*

But here’s the interesting part from the abstract:

Selection analysis identified 99 positively selected genes enriched in starch and fat metabolism pathways, indicating a diet change during feralization of dingoes. Interestingly, we found that 14 genes have shifted allele frequencies compared to dogs but not compared to wolves. This suggests that the selection affecting these genes during domestication of the wolf was reversed in the feralization process. One of these genes, ARHGEF7, may promote the formation of neural spine and synapses in hippocampal neurons. Functional assays showed that an A to G mutation in ARHGEF7, located in a transcription factor-binding site, decreases the endogenous expression. This suggests that ARHGEF7 may have been under selection for behavioral adaptations related to the transitions in environment both from wild to domestic and from domestic back to wild. Our results indicate that adaptation to domestication and feralization primarily affected different genomic regions, but that some genes, related to neurodevelopment, metabolism and reproduction, may have been reversibly affected in the two processes.

There are lots of arguments about how the dog got domesticated. One thing to remember is there is a distinction between population divergence of the ancestors of dogs from the ancestors of Eurasian wolves and the domestication of the dog in various steps and stages. One can imagine, for example, a close association between some groups of wolves and humans, with the former existing in a symbiotic relationship with nomadic bands. This state could persist for thousands of years (in fact, I have heard that this may resemble the relationship of the dingo to Aboriginal people, whose landscaping through fires may have been helpful to dingo predation).

Eventually, though humans settled down into sedentary villages. It is hard not to imagine that the village garbage pile dogs didn’t evolve to be even more human accommodating at this stage, with some of them being helpmates to human populations as work dogs (watch-dogs, hunting-dogs, and even war-dogs).

The dingo may illustrate a shift back toward more detachment from humans. The Aboriginal people never lived in large agricultural villages, so the opportunities for extremely close coexistence did not present themselves. But it is interesting that the dingo did not revert to becoming an Australian wolf, but remained distinctively dog-like. This may be a function of loss of genetic diversity through the bottleneck, a different ecological niche than the wolves of Eurasia, or, irreversible evolutionary genetic changes in the morphology and physiology of the canid lineage.

* Australians on the north coast have a legend of a dog arriving in a boat. Most likely they arrived from Sulawesi in Indonesia.

9 thoughts on “The dingo ate our domestication

  1. It’s really interesting that Australia was very close to the well-trafficked spice trade routes and islands in the now-Indonesian archipelago, but they never got an expansion and settlement from farmer cultures – they were aboriginal until the early modern era.

  2. In terms of not reverting back to wolf phenotype in some ways – could that just be also because those characters are more selectively neutral or purely path dependent than we might guess?

    Shame mustangs have such little time depth. Seems like you might not find as much in a similar study on them?

  3. “a different ecological niche than the wolves of Eurasia”, in terms of body and brain size it seems like that should be important. apparently dingoes have larger brain to body ratio than dogs, which is suggestive of some reversal of domestication syndrome (though dog breeds vary in this), but not total recovery to wolf absolute body size and brain size.

    probably predatory niche – as no large herds of grazing fauna to prey on in Australia? certainly not megafauna. and maybe some of Bergmann’s rule (where species are cosmopolitan, the warm climate varieties tend to have smaller absolute size) as much as this is not an absolute.

  4. @Matt – The largest extant species of kangaroos qualify as megafauna on body weight (but depends; different people seem to use different qualifying criteria) – pretty big animals, fast and certainly not defenceless, and lots of them. Dingoes successfully prey on them, but will go for animals in a whole range of sizes.

    Plus, much more recently, packs of dingoes are capable of bringing down horses, and feral water buffalo, which are big mean animals. I don’t know about feral dromedaries, of which Oz now has an over abundance (professional shooters cull 20-30,000 of them every year, but are not even making a dent in the camel population) – I have never heard of dingoes managing to kill a camel, but it would make sense for them to prey on the young, at least.

    It seems at least possible that dingoes caused the extinction of the thylacine on the Oz mainland (if they didn’t, what did? they kill feral cats) and have become the apex predator in their place, maybe by killing them directly. Dingoes are more capable hunters – thylacines were lopers, not fast runners, and were either solitary hunters or hunted in pairs, not cooperative packs like dingoes. I can’t imagine one or two thylacines bringing down an adult red or grey kangaroo – they’d never catch them, for a start.

  5. @Brett – It seems likely that climate in northern Australia would have deterred farmers from settling, plus locals would likely have turned nasty on anyone intent on staying permanently and disrupting their nomadic hunting routes. Even now, farming in that region is only possible with modern irrigation, and not easy; lots of failed attempts using modern farming methods for every modest success – cotton, rice, sugar cane and not a lot else, and the wild geese can make short work of a rice crop. OK for grazing cattle.

  6. @John, that sounds like they’re more capable of hunting large animals than I thought, though I still don’t think it’s a bad idea that the relative lack of large prey (for most of their evolutionary time as a divergent variety – dromedaries, horses, buffalo all pretty new) could be limiting their specialisation towards being quite so adapted to large prey as grey wolves (by large body size).

  7. @Matt – Agreed. Large prey are the exception (and they can’t be particularly adapted to that because the largest prey animals are very recent introductions – they just do it because they can); they are mostly going after much smaller prey animals. They are generalists, unlike e.g. African wild dogs. Farmers hate them because occasionally in one night they will go through a whole herd of sheep and kill all of them, apparently just for the hell of it; they can’t eat them all. But in some of those cases the real culprits could have been rogue sheepdogs or hybrids – it’s the subject of an ongoing bitter debate in Australia between sheep farmers and dingo conservationists. In some areas dingoes are classified as vermin and are subject to shooting and poisoning programs, and some areas have dog proof fences to keep them out, while there are groups in Australia dedicated to the preservation of dingoes in their ‘pure’ (i.e. unhybridised) form.

    There is some evidence that dingoes are actually favourable for the conservation of native animals because they keep down the population of feral cats that prey on smaller marsupials.

    I wouldn’t rule out some effect of Bergmann’s rule as well – larger body size would not be as well adapted to living in the very hot dry conditions they mostly live in.

    If raised from small pups, they readily make good pets, but need some special measures because of behavioural and dietary differences from domestic dogs. I had a pet dingo (illegally, but the local cops knew she was a real sweetie and obligingly turned a blind eye) from when I was 7 until I was 21; she was very well behaved and never once became aggressive to anyone. We kept her in a very large, heavily vegetated yard with a pair of ducks, and for a short period with a pair of very young kangaroos – she never went anywhere near the female duck or the kangaroos or the ducklings when a brood finally hatched, but made great sport out of giving the drake absolute hell – she would race down the garden, grab the drake around the neck while running full speed and swing him around her head; he had no neck feathers left, but she never seriously injured him. But she regularly stole the duck eggs and consumed them, which pissed off my mother, who liked to use the duck eggs to make cakes. And once she found four feral kittens living underneath our house, and she killed them all.

    I’m in the camp that wants to see dingoes conserved in their unhybridised form. Wild packs pose some risks to humans, but it’s the humans who need to be intelligent and informed, and adjust their behaviour, not a reason to exterminate the dingoes.

  8. @Matt and @John Massey

    Dingo’s are similar in size to the southern most wolf sub species in eurasia, we think of wolves as big animals around a 100 lbs but that’s only the northern sub species and even then they’re closer to 80 lbs on average.

    Arabian wolves are about 45 lbs on average according to wikipedia I don’t have primary citations to hands but that is about what I remember when I was researching canids in school. Indian wolves are similar in size.

    Very likely this is at least partially due to bergmans law but mexicans wolves are not as small so perhaps the megafauna theory has some merit as well. Indian and Arabian wolves historically at least were probably competitively excluded from a major role as big game hunters due to big cats which weren’t present in most of the range of the large northern sub species of wolf. Large Kangaroo are similar in size to medium sized deer species but dingo size seems good enough to take them down in a pack and coyotes are successful doing the same with mid sized american deer species.

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