Old dogs, new tricks: 3D geometric analysis of cranial morphology supports ancient population substructure in the Australian dingo

The dingo is a wild canid introduced to Australia within the last 5000 years. Existing research has identified up to three evolutionarily significant, geographically separated distinct populations of dingo on the Australian mainland. Contending explanations variably invoke ancient population substructure, separate introductions in antiquity, and disparate levels of recent domestic dog admixture. Here, I present an assessment of morphological variation in the dingo, applying 3D geometric morphometrics to compare the cranial forms of individuals from different regions in Australia, with the dingo's closest relatives, New Guinea Singing Dogs, domestic dogs and dingo-dog hybrids. Dingoes from southeastern Australia were found to be morphologically distinct from conspecifics to their northwest, including both desert, tropical and Fraser Island dingoes, being intermediate to New Guinea Singing Dogs. The close resemblance of these results to genetic population subdivisions indicates that dingo morphology likely reflects ancient population substructure related to a complex prehistoric introduction and dispersal scenario, rather than solely introgression from domestic dogs.