For decades, popular culture and a certain anthropocentric vision have projected the idea that the traditional family It was the most normal thing in the animal kingdom. However, biology has a habit of contradicting us and if we look Alaskan watersand specifically the belugas From Bristol Bay, monogamy is not only rare: it is evolutionarily inefficient.
The study. It has had as its objective analyzing the DNA of hundreds of these cetaceans for more than a decade, and confirms what we could call, in human terms, a lifestyle “swinger” either polyamorous among these animals. Although this word is more for our daily life, since in a scientific way it is called polygynandryand it is the secret of these whales to stay genetically healthy and resilient.
The myth of the “better half”. Choosing a life partner for whales is something that is not the norm in this case. To reach this conclusion, the researchers They didn’t just watch what they did.but carried out an exhaustive analysis of 623 genetic samples collected over 13 years in the Bristol Bay beluga population. And we are facing a very interesting population because it is geographically isolated and has about 2,000 individuals.
What they found was a mating system where both males and females mate with multiple partners. There is no “alpha male” that monopolizes females (polygyny), nor females that have only one consort. It is a constant and strategic exchange.
Stepbrothers everywhere. The definitive proof of this behavior is in the family trees that the study managed to reconstruct. When analyzing kinship, scientists came across a revealing fact: there were many half-siblings who shared a mother or father but not both.
The fact that it is very difficult to find full siblings indicates that season after season, females do not repeat partners, but rather change. A strategy that is aimed at maximizing reproductive success, since otherwise a few males would dominate the genetics and cause less genetic diversity.
‘Swinger’ as an advantage. We might think that this behavior is chaotic, but it is actually a very sophisticated biological defense mechanism. And constantly mixing genes with different partners ensures greater variability in the offspring to avoid serious diseases such as those that historically occurred. we have had in the European monarchies.
But the interesting thing is that it is a choice of the females who play an active role. In this case they are not passive, but actively choose the males to mate with to have great variability, possibly to ensure that their offspring have the best possible genetic combinations.
Its longevity. One of the characteristics of this species is that it can last for many years, and that is why maintaining genetic diversity through polygynandry allows them to adapt to long-term changes in their ecosystem.
And it is a finding that aligns with previous research, since a high diversity in the microbiome and population structure of these whales was already pointed out, but the mating system had never been confirmed.
A genetic lifesaver. The most fascinating thing about this discovery is how it rewrites our understanding of cetacean sociality. We often assume that highly intelligent and social animals tend toward monogamy (as is the case with certain birds), but the reality is that belugas demonstrate that you can have a complex society, care for offspring, and at the same time have a promiscuous sex life for the good of the species.
For conservationists, this is good news. Knowing that this population maintains high genetic diversity and avoids inbreeding itself means that they have better biological tools to cope with climate change and human pressure than other more “faithful” but genetically poorer species.
Images | Todd Cravens
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