Study finds natural selection shaping barn owl plumage

Scientists at the University of Lausanne have found that natural selection changed the appearance of barn owls over 10 generations in a large-scale genetic study of their plumage color and spotting.

Operative Information Center-OMM reports that the study, published in the journal “Nature Communications,” was led by Dr. Tristan Cumer and Professor Jerom Gude.

Researchers identified DNA variants associated with color and spotting by analyzing decades of field observations and sequencing the genomes of more than 3,000 owls. According to the scientists, an increase in genetic variants linked to reddish-brown plumage is explained not by random processes but by the direct influence of natural selection.

The study identified the MC1R gene, which affects pigmentation, as well as specific regions on the sex chromosome. However, MC1R is part of the melanocortin system, which influences not only color but also physiological traits such as responses to stress and aggression. The scientists therefore say natural selection may act directly on the birds’ stress tolerance rather than on plumage color, with the color change emerging as a side effect.

Barn owl plumage ranges from pure white to dark reddish-brown. White owls use moonlight when hunting, while birds with many black spots are more resistant to parasites and food shortages. Professor Alexandre Roulin, a co-author of the study, said environmental changes and prey availability — such as an increase in field mice — may have given reddish-brown owls an advantage.