To make matters worse, they simultaneously realized that the vanishing species was actually five. The Canadian researcher Robert Murphy found hints of this diversity back in 1991, but due to limited funding and restrictions on foreign researchers, he couldn’t follow up on them. Almost 20 years later, he teamed up with Che and others to collect tissue samples over 1,000 salamanders, and analyze their DNA. They found that these animals belonged to at least five separate lineages, and perhaps eight or more. According to the team, all five are distinct enough to qualify for species status.
There’s no settled way of defining what a species is, let alone how different two lineages have to be to count as distinct species. But Samuel Turvey from the Zoological Society of London, who worked on the study, says that “the level of genetic differentiation between the Chinese giant salamander lineages is comparable to that seen between other closely related amphibian species.”
Each of the five lineages also inhabits a separate river system, and since these animals don’t move very far, they’ve all been evolving independently for between 4 and 10 million years. “It always seemed possible that multiple species might exist,” says Che.
“This is very common with amphibians,” says Ariadne Angulo, who co-chairs the amphibian group of the International Union for the Conservation of Nature. There are many other cases where a single, wide-ranging species turned out to be several hidden ones. Those differences have big implications. When conservationists try to predict an animal’s fate, and thus how much effort should be put into saving it, “it’s based on the premise that you’re assessing one species,” says Angulo. “If it’s actually five, obviously their extinction risk is going to be very different.”
“With millions of years of divergence between the groups, my expectation is that these animals have adapted to their surroundings,” says Amy McMillan from Buffalo State University, who studies the related hellbenders. “If we mix them up with other genetic lines, we don’t really understand what that would do.”
The farms have essentially done that experiment: By trading giant salamanders across their entire range, they’ve created millions of hybrids. Thousands of these have made their way into the wild because the Chinese government, in a bid to conserve the species, pays farmers to release some of their stock. “They do that without knowledge of where the salamanders have come from, or of their genetics,” Cunningham says. “Their heart is in the right place but the methodology is very flawed.”
“Farms are releasing salamanders from the north, which gets very cold winters, into the south, which is subtropical,” adds Che. “It’s possible that cold-adapted genes from the north will be maladaptive in the south.” The various populations might also cross-breed, homogenizing the salamander gene pool and driving some lineages to extinction. This is already happening: All the individuals that the team recently caught from the Pearl and Yangtze rivers carry the DNA of the northern Yellow River lineage, rather than the indigenous salamanders that once lived in those waters.