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How a leopard changes spots?

Well scientists finally seem to have the reason, not only behind their distinctive marks, but also how the marks change as the animals? age

india Updated: Aug 05, 2006 19:32 IST
Asian News International
Asian News International

Ever wondered why adult leopards and cubs have different spot patterns on their coats? Well scientists finally seem to have the reason, not only behind their distinctive marks, but also how the marks change as the animals’ age.

Alan Turing had in 1952 come up with an equation that produced dead ringers for zebra hides and leopard spots, and now that same equation has been used to model how leopard spots can morph to more complex patterns as they grow old.

Turing had said two chemicals, known as morphogens interacted through a reaction diffusion equation to produce the different colours on the coats of big cats. While one morphogen caused the hair to turn black, another caused it to remain pale.

The differences in the rates at which these chemicals diffused through the coat, along with various reactions between the two, determined the patterns.

But Sy-Sang Liaw of National Chung-Hsing University in Taichung, Taiwan who replicated the patterns using Turing's equations, said their experiments revealed that more than just tweaking the parameters of the reaction-diffusion equation was needed to replicate the exact patterns on the model.

"The pattern of the jaguar was the hardest part. People who try to do the pattern with one stage only will never get it. You have to separate it into two stages," Nature quoted Liaw, as saying in his report in the Physical Review.

The task was to assume two stages of spot growth with different rules: the first to get the baby cats their spots, and the second to create the final configurations of spot patterns in adult cats, they said.

Anotida Madzvamuse, a mathematician who has worked on Turing models at Auburn University in Alabama, said as of now no one had found how the patterns created by these equations were made in a real cat, and the answer may lie in the changes due to size and age.

“No one has found a physical manifestation of morphogens, so it is unclear how the patterns created by these equations are actually made in a real cat. Adding two sets of rules for the morphogens complicates the picture even further. If it is a true reflection of what happens in cats, this means something to do with the animal's age must flip a switch in the biological rules by which their coat colours behave,” Madzvamuse said.

"Maybe the parameter values could be related to the size of the animal," he added.

First Published: Aug 06, 2006 15:00 IST