Scientists mapped the genes of the endangered Siberian tiger (or Amur tiger), both to understand the genes that make big cat species distinct from one another and to aid efforts to preserve genetic diversity in wild tiger populations. (Also see "Isolated Tigers Travel Surprising Lands to Find Mates.")

The largest tiger subspecies, Siberian tigers weigh as much as 660 pounds (300 kilograms) and grow to some ten feet (three meters) in length. Only about 450 Siberian tigers exist in the wild, and around 4,000 tigers total are thought to remain in their natural habitats. (See a National Geographic magazine interactive of big cats in danger.)

"We looked at this very large tiger first to see what made it distinctive