Why does Krishna—the tiger on the left—have darker black stripes? He’s pseudomelanistic. Krishna has a gene that makes the stripes in his coat grow darker and thicker.

These cats live in the Similipal Tiger Reserve in Odisha, India, which has more pseudomelanistic tigers than anywhere else in the world. The trait is recessive, so both parents have to have the gene to pass it to their offspring. Since the the gene is so common in this small tiger population, it’s much more likely for two tigers with this rare gene to mate.