Crossbreeding between species is everywhere. In the past and at present, in both plants and animals. However, crossbreeds such as the mule cannot reproduce, and in other species they are not viable.

Hybridisation sometimes has advantages

Although generally hybridisation can cause serious disadvantages for species conservation, sometimes hybrids have an advantage that can help a species to survive. Snow sheep, for example, owe their adaptation to cold temperatures to a cross with another species of sheep that could better withstand the cold. And some coral species will be able to survive future temperature increases better thanks to crossbreeding with other corals that already have such genetic adaptations.

Genetic rescue to the rescue

Hybridization can also offer a solution for genetically impoverished species. After all, they get extra genetic diversity for free after crossing with another species or subspecies. For example, the waning Florida panther was saved by crossing with the Texas cougar and, as an extra, sperm quality of hybrid males improved considerably, a prime example of genetic rescue.

Hybrids can also be important for the proper functioning of ecosystems, replacing extinct species. Thus, as users of the various benefits that humans derive from nature, also called ecosystem services, it is in our own interest not to deny the potential of hybrids. Unfortunately, this is not taken into account sufficiently in legislation, management or policy for protecting and monitoring of species.

Closing the gap between science and practice

To assist nature managers and policy makers, we recently collaborated with researchers worldwide to formulate practical guidelines to help them identify hybrids efficiently. After all, how do you figure out whether an animal or plant is a hybrid or not? That is not always easy, but such information is crucial to optimising the management of animals or plants. In addition, we proposed a pragmatic framework for incorporating hybridisation into conservation policy and management, supporting decision-makers to determine actions that enhance conservation benefits while mitigating potential harms of hybrids in reproduction, survival, genetic diversity and ecological functions.

By closing the gap between science and practice, we unlock the full potential of hybrids. And that is important, because hybrid crossings can offer endangered species the opportunity to survive in a rapidly changing world.

If you want to broaden your "Neaderthaler" view of hybrids, you can go here for a comics edition of “Genes on Wheels” on this theme.

The open access scientific paper can be found in Conservation Letters.