The offspring of California tiger salamanders and barred tiger salamanders are living proof that not all hybrids are mule-style genetic dead ends: They’re breeding their parents out of house and home. In a watershed instance of "hybrid vigor" among animals, Science reports, the progeny of two species for the first time have a higher survival rate than their ancestors.
The native Californians have been breeding with Texas’ banded species for 50 years, but scientists only recently compared the viability of the lizards. The former animal is a threatened species with a threatened habitat; the new discovery raises the question of whether the hybrids should be killed to protect the purer original amphibians. (Read more salamanders stories.)