Inbreeding threatens the Fennoscandian Arctic fox. In a recent report from the Norwegian Institute for Nature Research (NINA), researchers propose measures to ensure the long-term survival of the species.
Pups from the breeding station at Sæterfjellet in Oppdal, Norway, will contribute to the long-term survival of the Arctic fox. Photo credit: Craig Jackson/NINA
New analyses reveal that genetic variation is decreasing and inbreeding is increasing in several subpopulations of the Arctic fox. This leads to lower survival rates and fewer pups per litter.
"We must avoid further loss of genetic variation and increased inbreeding. To achieve this, it is essential to facilitate gene flow between subpopulations," says geneticist Øystein Flagstad at NINA.
New Generations on the Move
This means that more Arctic foxes need to move between the different subpopulations in Norway, Sweden, and Finland (Fennoscandia). Strengthening this opportunity is a key measure.
The Arctic Fox Captive Breeding Programme contributes to this effort by providing pups from the breeding station at Sæterfjellet near Oppdal, Norway. The researchers propose to increasingly release pups that are not closely related to the foxes already present in specific areas.
"We recommend prioritizing areas where the effective population size is particularly low or where inbreeding is increasing. The effective population size is a measure of how genetically robust a population is. It is influenced, among other factors, by the proportion of adult Arctic foxes that contribute with offspring and thereby pass on their genes," explains Flagstad.
Feeding Stations Connect Populations
Installing more feeding stations with pellets in areas between the larger core populations can encourage more Arctic foxes to migrate to and settle in these regions. This could lead to the establishment of new subpopulations, reducing the distance between the core populations. It may also be necessary to relocate Arctic foxes between subpopulations to promote genetic exchange.
At the turn of the millennium, the Fennoscandian Arctic fox population was on the brink of extinction. Only 40-60 adult Arctic foxes remained, spread across a few completely or partially isolated mountain areas. Since then, measures such as supplementary feeding, red fox hunting, and the establishment of the breeding program in Oppdal have contributed to a tenfold increase in the population.
Only Partial Success
However, this story is only partially a success due to the persistent challenges related to inbreeding. This is why the researchers are focused on finding targeted measures to counteract inbreeding.
In the report Genetic variation and inbreeding in the Fennoscandian Arctic fox population (summary in English), the researchers describe the levels of genetic variation and degrees of inbreeding in all Fennoscandian subpopulations and examine changes over time (2005–2023). They also analyze the effects of inbreeding and how it impacts adult survival rates within the population.
Optimizing the Effect of Releases
The next phase of the project is to optimize the effect of Arctic fox releases. During this year, the researchers will conduct a study where they simulate different strategies for releasing Arctic foxes and assess their impact on the genetic diversity of the species.
"The goal is to ensure that the genetic diversity of the Fennoscandian Arctic fox population keeps pace with the increase in the number of individuals. Hopefully, the population will continue to grow towards the vision of 2,000 adult Arctic foxes, while the measures we describe contribute to maintaining a genetically healthy population," concludes Flagstad.
Read the report here (summary in English): Genetic variation and inbreeding in the Fennoscandian Arctic fox population
Learn more about the Arctic fox here
Contact:
Øystein Flagstad
Nina E. Eide