How the cheetah gets its spots

A mutation in Taqpep changes a spotted cheetah pattern to a king cheetah pattern. Image: Greg Barsh/Ann van Dyk Cheetah Centre

There may be a big difference in size, but cheetahs and tabby cats have things in common.

If you look at a tabby-patterned house cat, it is not difficult to see that their coats are similar in colour and pattern to those of cheetahs and tigers, according to Christopher Kaelin from Stanford University in the US, “this suggests the pattern creating process is shared by all cat species but also can be tweaked to make different patterns types.”

All cats — wild or domestic — are born with their particular pattern, which may be due to an establishing process that is only active during early development. When this process is shut off the pattern is fixed, so as the surface area of the cat increases the markings will expand, but no additional spots or stripes are added. However, very little is known about how these markings are formed and controlled.

In the 1950s, British computer scientists Alan Turing suggested that periodic patterns in nature result from a self-organising process called reaction-diffusion, which is determined by the interaction of two diffusible substrates. So Kaelin and his colleagues searched the genomes of feral cats in northern California and determined that the same genes that produce the cheetah’s spots also control the house small cat’s patterns.

They also reported in Science that the loss of one of these genes (Taqpep) encodes a protease released form the surface of cells and disrupts these colour patterns without affecting any other part of the cat in question. “So, consistent with Turing’s original idea, our findings indicate that a diffusible protease helps to organise a skin patterns during cat development,” Kaelin explains.

One of the most striking examples of this mutation is sub-Saharan Africa’s king cheetah, which has a blotched pattern similar to that found on a tabby cat, also controlled by Taqpep. The researchers observed the mutation in a captive breeding program at the Ann van Dyk Cheetah Centre in South Africa because, while the king cheetah pattern occurs naturally in the wild, only a handful of sightings have been reported since the early 1900s.

Kaelin says it’s unlikely that there is any advantage in having the king cheetah pattern in the wild. “If anything, the blotchy appearance might be make them more conspicuous to prey.”

or blotched [bottom row]. Image: Helmi Flick “] to a blotched tabby pattern [second row]. Image: Helmi Flick”]

A mutation in Taqpep converts a mackerel tabby pattern [top row

 

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