Hybrids and the Environmental Protection Act

In the 43 years since it was written, the Endangered Species Act (ESA) has played a key role in the recoveries from near-extinction of several species, including the bald eagle, the humpback whale, and the gray wolf. However, the ESA doesn't address hybrids - organisms produced when individuals of two different species mate and produce viable offspring. The problem of what to do about endangered hybrids has now come to the forefront, thanks (or no thanks) to a powerful new tool in biology, DNA sequencing.

The classic definition of a species is "a group of organisms that under natural conditions tend to breed within that group." Most species can't breed with other species and produce viable offspring. But there are exceptions; wolves, for example, can (and occasionally do) interbreed with dogs or coyotes. And that brings us to the problem of which wolves, if any, should be protected by the ESA.

The ESA currently recognizes (and protects) two species of wolves. Gray wolves are found primarily in the western U.S.; their population is recovering, thanks to protection under the ESA. Red wolves were once found in the southeast U.S. but now exist only in captivity; they, too, are protected. In addition, scientists have recently suggested that wolves in the eastern U.S. should also be listed as a separate protected species, to be called the Eastern wolf.

But now new research, using DNA sequencing, has revealed that the Eastern wolf and the red wolf are actually hybrids, produced by interspecies mating between gray wolves and coyotes. That creates a problem for the ESA. If Eastern and red wolves are just hybrids of two true species, should we attempt to save them? And if there is just one species of wolf, does its total population still warrant protection under the ESA?

The Environmental Protection Act is showing its age. It needs to be able to take into account new findings derived from DNA sequencing. And it needs to address what to do (if anything) about hybrids.