When we think of spotted animals, cheetahs are often among the first that come to mind.

Cheetahs have around 2,000 spots, each forming a unique pattern that can be used to identify individual animals in wildlife management.

Across the animal kingdom, nature offers a fascinating variety of pigmentation patterns—ranging from spots and stripes to splotches and blotches—that have intrigued scientists for years. Research is revealing that these diverse patterns are governed by common biological and mathematical principles.

Learning from Nature’s Exceptions

The king cheetah, with its distinct coat pattern, was once thought to be a separate species of cheetah. Unlike the typical cheetah, it has a darker coat with large black splotches and stripes running along it's back. Researchers from the Cheetah Conservation Fund were part of a team that discovered this unique pattern is the result of a mutation in a gene known as Taqprep.

The Taqprep gene was first identified for its role in affecting coat color in domestic tabby cats. In tabby cats with the normal Taqprep gene, a narrow, vertical stripe pattern appears on a light background, known as the mackerel pattern, because it resembles fish bones.

Mutations in the Taqprep gene, however, produce a blotched pattern, which scientists found closely resembles the expanded dark patches seen in the king cheetah. Taqprep plays a key role in establishing the light and dark regions of the skin during development, and the patterns on the skin correspond directly to the fur's pigmentation.

Even rarer than a king cheetah is a spotless cheetah. In 2012, a cheetah without any spots was spotted at the Athi Kapiti Conservancy in Kenya, nearly a century after the last recorded sighting. While the cheetah had hundreds of tiny freckles on its back, from a distance, it appeared uniformly tan.

Some experts speculate that this spotless cheetah might be mistaken for a lion, which could provide an evolutionary advantage. Unlike other patterned cats, such as tigers or leopards, whose spots and stripes help them blend into the shadowy forest, cheetahs live in open savannas where their spots help camouflage them in tall grass.

Pattern Formation in Animals

Biology shows us that genes are activated at specific times and in specific locations during an animal's development, shaping everything from body form to skin pigmentation. Mathematical models suggest that the wide variety of pigmentation patterns we see in animals—whether spotted, striped, or a blend of both—could arise from a shared underlying mechanism.

One such model, known as reaction diffusion, demonstrates how the diffusion of two molecules across the skin during development can create many of the patterns we observe. By adjusting the rate and manner in which these molecules spread, a range of striped, spotted, or intermediate patterns can form on the skin.

Have you noticed that cheetahs have stripes on their tails? Reaction diffusion models predict that the narrow width of a cheetah's tail would cause its spot pattern to shift into stripes. In contrast, the wider tail of a leopard should maintain spots almost all the way to the tip—just as we observe in nature.

While scientists are still unraveling the full complexity of pigmentation patterns, it’s clear that nature continues to offer fascinating clues for future research.