The brown bear that lives in the Apennine Mountains in central Italy is different from all other brown bears. He is not only a bit smaller, but also a lot nicer – at least less aggressive.
The small and isolated population of about fifty animals today in the mountains surrounding the town of L’Aquila has a long history of proximity to human settlements. Previous research suggests the subspecies split from other European brown bears 2,000 to 3,000 years ago and has remained completely isolated since Roman times. A major cause of the decline and isolation was likely deforestation associated with agricultural expansion and increasing population density in central Italy.
Italian researchers compared the DNA of the Marsican brown bears with that of a larger European population in Slovakia and with a previously published genome of American brown bears. As expected, Marsican brown bears had significantly less genetic variation than their counterparts elsewhere and had a high degree of inbreeding.
The researchers also see traces of selection in the DNA for behavior-related genetic variants, probably caused by the selection of more aggressive bears by humans. Centuries of proximity to humans has compromised the bear’s survival through population decline and genetic erosion, but it has also led to the evolution of a subspecies that can better coexist with humans.
The researchers saw mutations in six of the seven genes that they identified as ‘involved in exaggerated friendliness’ compared to other bears. In addition, they also saw changes in domestication genes known from horses, cattle and silver foxes. The Marsican brown bear has therefore become genetically friendlier.
That is something to take into account, the researchers write, if it is ever necessary to introduce fresh blood to increase the genetic variation in the population. Then you can’t just add another European brown bear, because then you run the risk that the genetically ingrained aggressiveness will return, and therefore the risk of conflicts with people.
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