The Alpine newt actually consists of five different species, biologists from Leiden discovered. While these species look very similar, they are clearly distinguishable through DNA analysis. This insight is a major step forward for the conservation of these newts.
Crypticspecies
Biologists from Leiden University and Naturalis Biodiversity Center, together with an international team of scientists, have discovered five "cryptic species" within the Alpine newt. Cryptic species are distinct species that look so much alike that, to the naked eye, they appear to be the same.
"Our senses are too limited to perceive the full extent of biological complexity," explains evolutionary biologist Ben Wielstra. "Ultimately, it is the organisms themselves that decide whether they can interbreed and thus belong to the same species—or not." Two animals might look identical to us, while a world of difference exists between them. DNA provides the solution: it serves as an objective measure to see if populations are actually exchanging genes.
What isa species?
In theory, the concept of a "species" is simple: if two individuals can produce fertile offspring together, they belong to the same species. Humans and cats cannot have children together and are therefore two different species. German Shepherds and Chihuahuas can (with a little help from the breeder), so we call them one species. However, nature rarely sticks perfectly to the theory, which is where things get complicated. "Nature doesn't care about the labels we humans stick on it," says Wielstra.
The puzzleof the newts
Alpine newts are a special case. Scientists have long suspected that they weren't dealing with a single species, but rather a group of cryptic species. Although large genetic differences seemed to exist between certain populations, until now, not enough DNA had been studied to determine if gene exchange was still taking place. Thanks to recent technological developments, it is now possible to consult much more DNA at once. To solve the Alpine newt puzzle, thirty international scientists joined forces to study newts from all over Europe.
Museomics:DNA from depots
The researchers used a specialized technique that allows thousands of specific DNA segments to be "captured" from a large number of newts simultaneously. By reading the sequence of these segments, a DNA profile is created for each individual. These profiles can then be compared. "A major advantage is that this technique also works well on newts that have been sitting in jars of alcohol in museums for decades," says PhD candidate Anagnostis Theodoropoulos. This allowed the researchers to map out where the different genetic groups within the "Alpine newt complex" occur and to what extent they still exchange genes.
Splitting the Newt into five
The results were clear: the Alpine newt consists of five genetic groups that only exchange genes to a very limited extent. The researchers therefore recommend recognizing these five groups as distinct species. Wielstra: "If you put them together in an aquarium, you’ll certainly get baby newts. But when we look at the DNA in the wild, we see that the groups do not merge because the hybrids don't make it for some reason. Some groups genetically split off more than ten million years ago."
"The biggest surprise was an Alpine newt species with a very limited range: the Vlasina plateau on the border of Serbia and Bulgaria," says bioinformatician Stephanie Koster, who started the project during her research internship as a student. This species does not yet have an official scientific name; the researchers will formally describe it later. The recognition of these five species lays the foundation for better conservation efforts.
More information
The article “Five hidden species in a widespread European vertebrate: disentangling the alpine newt cryptic species complex through genomic phylogeography” appeared in Molecular Ecology this week.
Text: Ben Wielstra, Stephanie Koster en Anagnostis Theodoropoulos Instituut Biologie Leiden, Leiden Universiteit & Naturalis Biodiversity Center
Photo’s: Michael Fahrbach, Milena Cvijanović, Scacciamosche (through Getty Images)