As controversial as the spread of wild wolves in Germany is, hybrids are even less popular. Mixed breeds of feral domestic dogs and wolves are often a problem because of their behavior, and their genes also falsify the genome of the wild animals. A new method now makes it easier to identify such outwardly often inconspicuous hybrids based on their faeces or hair samples. It shows that there are hardly any such hybrids in Germany so far.
More than 20 years ago, wild wolf pups were born again for the first time in Germany in northeast Saxony – a first since the native wolf was exterminated by humans around 1850. For a good ten years, wild wolves have been spreading rapidly in Germany. But this not only brings problems for cattle farmers and the acceptance of these predators, which were once common throughout Central Europe. The comeback can also lead to undesirable interbreeding of wolves with feral domestic dogs. “Especially at the beginning of such a resettlement, the probability that wolves will mate with domestic dogs is increased – simply due to the lack of a selection of sexual partners of their own kind,” explains Carsten Nowak from the Senckenberg Research Institute and Natural History Museum in Frankfurt.
Why mixed race can be a problem
However, knowing whether and to what extent such hybridizations occur is important for wolf management. On the one hand, the hybrid wolves can behave differently than wolves and are often less shy, for example. On the other hand, the dog genes introduced at the crossings change the genetic makeup of the wolf, because the hybrids are still fertile and fertile. Theoretically, it is possible that as a result of this, more and more dog genes will accumulate in the wolf’s gene pool over time. “In addition, the social acceptance of wild wolf-dog hybrids is low. Therefore, hybrids are usually taken from the wild, ”explains Nowak.
But recognizing the dog-wolf mix is anything but easy in the wild. Outwardly, the hybrids hardly differ from their wild relatives and, genetically, domestic dogs and wolves are very similar. For an identification, a good quality DNA sample and a complete sequencing of the genetic material are necessary in order to be able to recognize the deviations. “However, this method is far too time-consuming for routine monitoring of wolf populations,” explain Nowak and his team. They have therefore developed a method that will make it easier to identify dog-wolf mixed breeds in the future.
New test makes identification easier
For the new test, the researchers selected 96 genetic markers in the genome of dogs and wolves, which typically differ between the two and which can also be used to identify hybrids. On this basis, they developed a simple test array that contains specific binding molecules for these 96 gene building blocks. The color change then shows which markers are present or not. In addition, the scientists optimized the process so that it also works with samples with little or poor DNA. “The new method has a significantly higher resolution than conventional methods and allows the reliable detection of hybridization events even after several generations,” explains Nowak.
Thanks to this method, dog-wolf mixed breeds can now be identified more easily using the DNA from fecal samples, hair or saliva residues from torn prey. In the first tests, only 2.7 percent of all samples examined prove to be unsuitable. An initial inventory based on samples from the German wolf regions also showed that wolves in Germany do not currently have any increased proportions of dog genes. “In our study, we did not find any increased proportions of dog genes in the wolf samples from Germany,” reports Nowak. “There are similar findings in other regions of Europe where hybrids are consistently removed and there are also hardly any stray domestic dogs, such as in Scandinavia or the Alpine region”.
The new method is already being used routinely in German wolf monitoring. However, the researchers advocate standardized use of the process across Europe. “In this way we could identify areas in which, for example, wild dogs need to be controlled more closely in order to ensure an ecological separation from the wolves,” says first author Jenni Harmoinen from the University of Oulu in Finland.
Source: Senckenberg Society for Nature Research; Technical article: BMC Genomics, doi: 10.1186 / s12864-021-07761-5