{description}Manatees gently paddling on the surface of warm waters have revealed a startling connection with fish and mice. These aquatic herbivores are mammals that evolved from four-legged ancestors into legless swimmers. Stanford Professor David Kingsley of the Developmental Biology Department has recently unraveled one of the secrets behind their evolutionary development, demonstrating that a single gene known as Pitx1 can affect highly divergent species.Discovery of the Pitx1 Gene Through research at the Stanford School of Medicine, Kingsley determined that manatees had asymmetrical pelvic bones - the left pelvic bones are larger than their right pelvic bones. Though initially this trait may not appear important, Kingsley had found a similar trend in distinct populations of threespine stickleback, a species of fish that once had pelvic fins. Larger left pelvic bones also pervade in these populations of fish now lacking pelvic fins.  {/description}