Domestic cats often resemble their larger, wilder counterparts with black, striped or tawny fur that presumably helps the big hunters blend into the landscape. For scientists, the genes involved in the evolution of cats color patterns have been equally well camouflaged. But a new study in Science reveals a mutation shared by housecats and cheetahs, which may explain how the cat got its stripes or, in this case, its blotches.
The sharp, evenly spaced stripes of the tabby cat are among the most common of coat patterns. In some tabbies, however, the stripes look more like long, irregular swirls. Although fairly common in domestic cats, this pattern (called blotched by geneticists and cat fanciers) is unusual in the wild. In fact, cheetahs with the blotched pattern were initially thought to be a separate species: They were crowned with the name king cheetahs to distinguish them from the more common, spotted kind.
To pinpoint the gene responsible for the difference, an international team of researchers scanned the genomes of feral cats that had either stripes or blotches. Their search led to an unnamed gene about which little is known except that it produces an enzyme that cuts up nearby proteins.
The study was led by Christopher Kaelin, a senior scientist in the laboratory of Greg Barsh (of the HudsonAlpha Institute for Biotechnology and Stanford University) and Xiao Xu, from the National Cancer Institute-Frederick National Laboratory for Cancer Research and the Sichuan Key Laboratory of Conservation Biology on Endangered Wildlife in Sichuan, China.
The researchers found that every blotched tabby had mutations in both copies of this gene, whereas every striped cat had at least one copy without the mutation. They then found the distinctive mutations in the same gene among DNA samples from a pedigreed family of king cheetahs, confirming their suspicions that mutations in the gene, which they dubbed Taqpep, turned ordinary stripes into the more regal blotches.