The study reveals that wild birds possess genetic predispositions to learn population-specific songs

Genetic predispositions drive the learning of population-specific songs in wild birds, a new study from Stockholm University shows. By studying adult hosts that had been moved as eggs from the Netherlands to Sweden, the researchers found that the songs of the relocated birds resembled both their social environment in Sweden and their ancestral Dutch population.

These results show how genetic differences can influence cultural variation in birdsong and how they, together, can contribute to mating barriers between bird populations.

“In nearly half of the world’s bird species, birdsong is socially learned, mimicking the songs of adults, much like human children learn languages,” says Samyuktha Rajan, who is a Ph.D. student at Stockholm University and lead author of the study published in Current Biology.

As individuals learn songs from each other, mistakes inevitably occur, leading to variations in song between populations of the same species, similar to the formation of human languages. In birds, these differences are often sufficient to reduce mating between individuals from different populations.

Despite decades of interest in how population differences in learned song arise, a long-standing mystery is how these differences persist when individuals are dispersed among populations. Individuals moving from one population to another must bring their own population’s songs with them, resulting in the collapse of any accumulated song differences between populations.

To answer this, researchers at Stockholm University collaborated with researchers at the University of Groningen. The researchers moved dirty flycatcher eggs from a population in the Netherlands to Sweden, where they were raised by Swedish parents.

The researchers then compared the songs produced by the adult males that hatched from these translocated eggs with those of their ancestral Dutch population and their local Swedish foster population.

“We found that the songs of displaced males were generally very similar to the Swedish population—underscoring the importance of social learning in song development. Interestingly, however, displaced males selectively learned those elements of Swedish song that were more similar to the Dutch population, despite never being exposed to Dutch songs, this resulted in their songs resembling both the native Swedish population and their ancestral Dutch population,” says Rajan.

“This suggests that in addition to the critical role of the social environment, pied flycatchers also have a genetic predisposition to learn the songs of their native population.”

These findings shed light on how genetic variation can influence cultural change. The researchers propose that as songs continue to vary between populations, genetic predispositions must change along with them. Over time, this process can reduce the likelihood that individuals originating from different populations will mate with each other, thus promoting the formation of new species.