Wild Tracks

On behalf of the world's wild species

Taz Speeds Up Evolution

The Tasmanian Devil is probably best known as the inspiration for the Looney Tunes cartoon character ”Taz”. The cartoon does resemble a stylized Devil (prominent canines, large head, short legs) and the behavioral similarities between the two consist of a noisy comportment, voracious appetite, and shy demeanor.

The real Tasmanian Devil (Sarcophilus harrisii) is a meat-eating relative of the kangaroo. Like all Australian marsupials, the young are carried in a pouch through their early infancy. Taz is found in the wild only on the Australian island of Tasmania.

The devil's ears turn bright red when aroused

The devil's ears turn bright red when aroused

The size of a small, stocky, muscular dog, the Tasmanian Devil has black fur, an offensive odor when stressed, an extremely loud and disturbing screech, and is ferocious when feeding. It is known to both hunt prey and scavenge carrion and although it is usually solitary, it sometimes eats with other devils.

Despite their ferocity, Devils now face a new and very deadly enemy.

First discovered in 1996, Devil Facial Tumour Disease (DFTD) is an infectious cancer spread by bites. Within a year of its discovery, it had spread to half the devil’s range. About two thirds of Tasmania is now affected, and infected populations have declined by up to 90 percent.

Visible signs of DFTD begin with lesions and lumps around the mouth. These develop into cancerous tumors that may spread from the face to the entire body. The tumors interfere with feeding, and the affected animal may starve to death.
Now new research suggests that Tasmanian devils are modifying their behaviour to fight the fatal cancer affecting their survival, indicating that evolution can work fast when it needs to.

DFTD primarily afflicts adults older than two years, killing them within a few months. But zoologists at the University of Tasmania have found that the disease has prompted changes in the devil’s behaviour and physiology, which might aid their survival.

They found a 16 fold increase in the proportion of females breeding at only one year of age, compared with pre-DFTD times.

Such precocious sexual maturity might be due to the absence of older, dominant females who have already succumbed to DFTD, giving young animals earlier access to mates. But genetic changes also play a part, as the earlier individuals can reproduce, the greater the chance of them having offspring before DFTD kills them. Such changes might lead to rapid adaptation towards a population that is genetically and demographically more robust to the effects of DFTD, say zoologists.

Time will tell if those changes will be fast enough to stem the decline – some studies have indicated that DFTD could drive the devils to extinction in only 20-25 years.

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