Lifestyle of Australian dingo transformed after arrival of Europeans

Over 3,000 years ago, dogs were introduced to Australia and New Guinea. Here, they were shaped by the landscape into what we now know as the dingo.

But, when domestic dogs arrived from Europe alongside colonists, these animals were reshaped again. It began a period of interbreeding between the two distinct canine populations, giving dingoes genes that may have helped them to avoid disease, while also creating new breeds of pooch, such as the Australian cattle dog.

New research, published in Proceedings of the National Academy of Sciences, has laid out how Australia’s apex predator was transformed by these interactions. By analysing the remains of living and preserved dingoes from the past 2,350 years, scientists were able to track significant changes in the diet and genetics of these animals.

Dr Lachie Scarsbrook, the study’s lead author, says that the most significant impacts happened in the past century as dingo populations plummeted.

“For decades, the war against dingoes was fought with bullets,” Lachie says. “However, this paled in comparison to the aerial baiting programs which started in the mid-twentieth century where poisoned meat was dropped from helicopters to kill dingoes en masse.”

“With declines in their numbers, dingoes would have been forced to abandon their social structure and procreate with feral European dogs when it became too difficult to find a suitable mate. It’s a story that’s been seen before in animals like the Scottish wildcat, and it’s repeated itself here.”

The researchers have called for action to help conserve the dingo, and protect its vital role in Australia’s ecosystems.

Australia’s changing predators

For millennia, Australia was dominated by thylacines. These apex predators were wolf-like marsupials unique to the continent that hunted wallabies, birds and many other animals.

This all changed around 3,200 years ago, when thylacines on mainland Australia went extinct. A small population hung on in Tasmania until the last known member of this lineage died in 1936.

Exactly why those on the mainland went extinct is a matter of debate, but is likely to have been a combination of factors. A shifting climate, advances in human hunting and the introduction of dingoes are all likely to have played a part in the loss of these carnivores.

With thylacines gone, dingoes were left as the largest predator. As they spread across the continent, these animals acquired adaptations to Australia’s rugged terrain, such as flexible joints.

Then in 1788 the European colonisation of the continent began. Lachie says that this event “changed Australia’s ecosystem forever”.

“Europeans altered fire regimes and other traditional methods of land management after they arrived and developed large areas of land for grazing sheep and cattle,” Lachie continues. “This significantly altered the vegetation, and even the climate, across Australia.”

“They also introduced numerous invasive species that plague the landscape, most notably rabbits, feral cats, and foxes. Predation by these animals changed the abundance of natural dingo prey species, such as the dasyurids.”

These changes even affected the dingoes on a chemical level. Museum specimens from before and after European colonisation show significant differences in the amount of certain carbon and nitrogen isotopes within their tissue.

Declines in levels of Nitrogen-15 suggest that dingoes were forced to eat larger animals, such as emus and kangaroos, presumably as cats competed with them for smaller prey. Meanwhile, a drop in Carbon-13 reflects the shift in vegetation that occurred as habitats were cleared.

How have dingoes been affected by dogs?

These weren’t the only changes, however, as the team also found shifts in dingo DNA. The team found some evidence of early breeding between dingoes and dogs after the arrival of Europeans, but this hybrid ancestry didn’t get passed on.

Lachie says that this early interbreeding would have been limited, as dogs and dingoes led largely separate lives.

“When European dogs first arrived on Australia’s shores they were vastly outnumbered by dingoes, which would have reduced opportunities for interbreeding,” explains Lachie. “Dingoes had also evolved to reproduce seasonally, unlike other dogs that mate all year round.”

“They also have a completely different social system to European dogs, and that would have kept them dingoes and dogs apart.”

European dog ancestry only became common in dingoes from the mid-1960s, following the widespread introduction of dingo control programmes. It now represents around 12% of the ancestry of dingoes living in southeast Australia.

The researchers suspect that the proportion of dog DNA has increased partly as a result of falling dingo populations, but also because it may help them survive in altered landscape. Some potential benefits include reducing inbreeding levels and providing disease resistance.

In northwest Australia, on the other hand, dingoes don’t have any European dog DNA. The researchers believe that this is because dogs are less common in this more sparsely populated area, while dingo control programmes have proven less successful.

Together, the results suggest that, even where interbreeding has occurred, dingo populations remain distinctive and capable of supporting themselves if they are given the chance to thrive.

“Rather than prioritising ‘purity’, future conservation efforts should focus on maintaining large enough populations for natural selection to operate effectively,” Lachie adds. “This will ensure that dingoes can maintain their position as Australia’s apex predator.”