Population movements

By using genetic analysis tools, we study the progressive history and the genetic relationships between different Barn Owl populations. On various temporal and geographic scales, we then trace the evolution of these populations of birds.

Barn Owl History

In addition to the Barn Owls found in Switzerland, there are numerous Barn Owl species around the world. All these different owls share a common ancestor who appeared more than 45 million years ago in Asia. Slowly, they colonized the entire world, separating into distinct species. Currently, Barn Owls can be found almost everywhere. The most common (once considered a single species) are the Tyto alba which range across Europe and in Africa, the Tyto furcata in North America and the Tyto javanica in Australasia. There are other species a bit more distant, like cousins, including the Masked Owl, the Lesser Sooty Owl, the Greater Sooty Owl, and the Golden Masked Owl. We study the links between these different species to trace the evolutionary history of the great family of Barn Owls, the Tytonidae. In this way, we can understand who are the most closely related and the pathways used to colonize the globe.

Restricted movements

During the Earth’s ice ages, many living organisms moved into “refuge” zones, places with milder climates where they could survive. At the end of the last ice age, roughly 10,000 years ago, the living organisms that had taken refuge in Northern Africa, the Middle East, and the Iberian Peninsula began to recolonize Europe. The genetic analysis of numerous individual owls, who keep traces of their origins in their DNA, has shown us that the Barn Owls currently in Europe come primarily from a refuge on the Iberian Peninsula.

The movements of animal populations are often restricted by physical barriers like mountain ranges or great bodies of water. These elements need to be considered during our analyses. Studying the movement of owl populations on a global scale indeed shows that Barn Owls went around mountain ranges (like the Alps or the Rockies in the United States) and very rarely crossed oceans like the English Channel.

Increasingly detailed

Thanks to current genetic tools, and the power of the calculations we can use, it is now possible to analyze great quantities of data. This means that we were able to decode the entire genome, the entire DNA of an individual (in contrast to only a few DNA fragments in earlier study periods). The genome of a Swiss Barn Owl was sequenced, as were other European owls and those coming from the Mediterranean Basin.

These new data enable us to deepen the demographic history of European owls. They will also serve for the study of particular cases, like the Mediterranean islands which may harbor very old populations having survived in one place since the last ice age.

Another interesting case is the Barn Owl of Great Britain and Ireland. These owls are white, while their continental peers are reddish-brown at the same latitude. A Barn Owl’s color is genetically determined. Such great differences between the populations of the British Isles and the continent raise questions as to their respective genetic patrimony, meaning all the genes of each population. Are there genetic differences between these populations? Did they evolve separately? We study which mechanisms explain these color differences and why they persist (selection, chance, etc.).