Issue of the Week: Defining a Species


Researchers from the University of New South Wales recently determined that dingoes are not just dogs but should be their own distinct species. The study used museum specimens from more than a century ago that show physical distinctions between a dog and a dingo. But, is that really enough to define them as a separate species?

Basic biology defines a species as a group of individuals that interbreed and produce fertile offspring that can also interbreed.  If it is not possible for two animals to produce fertile offspring in nature, they are different species.  Under the basic definition, dogs and dingoes are the same species. Dog-dingo hybrids exist and can produce fertile offspring. Wolves, coyotes and domestic dogs are considered different species, but they can interbreed and produce viable offspring.

Canine hybrids are rarely noticed in the wild because their looks resemble a wolf, coyote or domestic dog. Another reason is that canines of the three recognized species are geographically separated, have different life histories, or choose only to breed with animals of similar size.  Wolves may not breed with smaller coyotes or domestic dogs. Coyotes may choose not to breed with a poodle that just came back from the groomer.  An animal often chooses to breed with another based upon specific traits that the other individuals of the same species exhibit because it will maximize their fitness and reproductive success.

Members of the same species share external and internal characteristics which develop from their DNA. The closer relationship two organisms share, the more DNA they have in common, just like people and their families. Dogs, wolves, coyotes and even dingoes all have DNA in common because they evolved from a common ancestor.


The ability to decipher DNA has advanced in the last century. Being able to map out the makeup of two organisms and compare them side-by-side has aided scientist in the discovery of new distinct species. However, DNA can also show that two organisms that look distinctly different are actually the same species. For example, all domesticated dogs belong to one species, despite looking markedly different. Differences exist in size, build, and coat, but most domesticated dogs can interbreed and produce viable puppies that can mature and reproduce.

Then at what point is a dingo a different species from other canines?  Perhaps, in the thousands or even millions of years it takes for a species to evolve, dingoes will eventually become so different from other canines, that breeding with a domestic dog would produce unviable offspring, a litter of mules.  Are humans just impatient?

Looking at the entire sequence of DNA for distinctions and patterns between individuals, some geneticists would argue that the dingo is a different species.  More than a century ago scientist would have classified all the specimens as the same species. Humans are driven to categorize and classify everything. We do it with everything in our lives. Unfortunately for our peace of mind, nature doesn’t always go along with the game. The reality is that there are many “in between” situations when it comes to the distinctions between species.

Twice a week, SCI Foundation informs readers about conservation initiatives happening worldwide and updates them on SCI Foundation’s news, projects and events. Tuesdays are dedicated to an Issue of the Week and Thursday’s Weekly Updates will provide an inside look into research and our other science-based conservation efforts. Follow us on Facebook and Twitter for more SCI Foundation news. 

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