The survival of small animal populations remains a critical issue, as such groups are at high risk of accumulating harmful mutations. American scientists, using the example of beluga whales living off the coast of Alaska, have discovered that one of the most effective strategies for species preservation may be a polyandrous mating system—that is, changing partners.

Characteristics of Isolated Beluga Populations

Beluga whales are highly social marine mammals adapted to life in the harsh conditions of the Arctic and Subarctic. Of particular scientific interest are isolated populations of these animals. For example, in Alaska’s Bristol Bay, there is a group of belugas numbering only about 2,000 individuals. For such small populations, the main threats are the loss of genetic diversity and inbreeding—mating between close relatives, which leads to the accumulation of harmful mutations and reduced offspring viability.

Genetic Research and Its Results

Despite these risks, the beluga population in Bristol Bay has successfully avoided negative consequences over many generations. Over 13 years, scientists collected 800 skin biopsy samples from wild belugas and conducted genetic analyses. Using molecular genetics methods, they created “genetic passports” for 623 individuals, allowing them to accurately determine kinship ties among the animals, similar to forensic genetic testing.

With the help of specialized computer programs, researchers identified the parents of each calf, found siblings, and assessed how many offspring each adult produced. The analysis revealed that belugas practice polyandry: both males and females have multiple partners throughout their lives.

An Evolutionary Survival Strategy

This conclusion was supported by the fact that most sibling pairs turned out to be half-siblings—they shared only one parent. Such a mating system helps maintain high genetic diversity and minimizes inbreeding. As a result, the population demonstrates stable genetic health.

Scientists concluded that the “partner exchange” system is an evolutionary response to the challenges of small population size. Constant mixing of genes from different parents creates complex kinship networks rather than closed family clans, sharply reducing the likelihood of close relatives mating.

Biological Advantages for Males and Females

For females, this approach acts as a kind of “genetic insurance,” spreading risks and increasing the chances of producing healthy offspring from the most suitable father. Males, with their long reproductive period, can gradually accumulate offspring without entering risky competition for dominance in a single season.

Conclusion

Thus, the study showed that the polyandrous behavior of beluga whales is a subtle biological mechanism specifically “tuned” to maintain genetic health in a small population.