In a recent issue of GENETICS, Darin Rokyta and colleagues reported the results of a large survey of venom diversity across two snake species sharing nearly identical ranges and similar habitats in the southeastern United States. As expected, the mix in one species—the eastern diamondback rattlesnake—varied considerably from place to place. But the eastern coral snakes told a completely different story. In contrast to its rattlesnake neighbors, no matter where a coral snake came from, its venom was always the same.

Rokyta says the team was shocked by this lack of variation. “This is the first time anyone has looked at venom variation at this scale, and everybody has assumed that the co-evolutionary arms race would cause local populations to diverge quickly.”

The results not only challenge this assumption, they provide crucial information for rattlesnake conservation and coral snake antivenom development.