Different animal species often look different from each other, but many are very similar in appearance. That is why the diversity of such groups remains hidden from the eye – only analyses of the genetic material, the DNA, reveal the differences. Genetic studies are, among other things, important for the protection of species: A large number of species that are actually endangered would otherwise be overlooked. These ‘hidden’, so-called cryptic species are found mainly in the tropics. But there are also surprises in the seemingly well-known animal world of Europe.

In 2017, genetic analyses showed that in Switzerland two species of slow-worm occur instead of one, as previously thought. There is an easy way to tell them apart in the wild, though: One occurs north and the other south of the Swiss Alps.