Despite cross breeding, Australian dingos have managed to keep their distinctive head shape. This, researchers say, is good news, as any changes to skull shape could threaten both the species' survival and the local ecosystem.
Dingos (Canis dingo) are Australian wild dogs and the continent's largest predator. Dingos were first introduced to Australia 3,000 years ago, and remained isolated from other canids - dogs, wolves, foxes and jackals - until European settlers arrived with domestic dogs. This resulted in cross breeding, or hybridization, between dingos and domestic dogs, and ultimately a decline in pure-bred dingoes.
Following the evolutionary history of dingos, researchers from the University of New South Wales (UNSW) discovered hybrid skulls were indistinguishable from those of pure dingoes, meaning they could not tell the difference between skulls.
"We know that cross breeding has an effect on the dingo gene pool but what we didn't know until now is whether cross breeding changes the dingo skull," said William Parr, study lead author and postdoctoral research fellow at UNSW Medicine's Surgical and Orthopaedic Research Laboratory, in a news release. "This study has shown us that the dingo skull shape, which in part determines feeding ability, is more dominant than dog skull shapes."
Changes in skull shape is thought to be one of the main threats to the survival of a species as it evolves since it dictates feeding habits. Essentially, any change to an animal's diet could have cascading impacts throughout an entire ecosystem, by disrupting predator-prey relationships and causing an imbalance of local food resources.
Using medical CT scanners, UNSW researchers constructed 3-D models of the skulls of dingoes, domestic dogs and hybrids. They then used sophisticated 3-D shape analyses to identify differences among the skulls and determine whether they could correctly be assigned to one of the three groups, solely based on their shape.
Based on their findings, researchers believe the dominance of the dingo skull shape is most likely due to recessive, or potentially adverse, traits being fixed in the wild dogs. Furthermore, their findings suggest that other canid breeds have narrower gene pools than the dingo.
"This is the result of selective breeding to maintain breed standards, or selecting for useful working traits," Parr added.
In other words, the dingo resisted any evolutionary changes to its skull in order to maintain its ecological niche as a predator.
Until now, not much was known about how different regions of the skull may evolve on a short time scale, such as the cross breeding of domestic dogs with dingoes.
"Those patterns have implications for understanding variation in the wild, which is important for predicting how an animal may respond to future ecological challenges," study co-author Laura Wilson, a postdoctoral research fellow at UNSW Science's School of Biological, Earth and Environmental Sciences, concluded.
Their findings were recently published in the journal Evolutionary Biology.