Primary data on skull and brain morphology for: Geographical patterns in seasonal changes of body mass, skull, and brain size of common shrews

Some small mammals exhibit Dehnel’s Phenomenon, a drastic decrease in body mass, braincase and brain size from summer to winter, followed by regrowth in spring. This is accompanied by a reorganization of the brain and changes in other organs. The evolutionary link between these changes and seasonality remains unclear, although the intensity of change varies between locations as the phenomenon is thought to lead to energy savings during winter.

Here we explored geographic variation of the intensity of Dehnel’s Phenomenon in Sorex araneus. We compiled literature on seasonal changes in braincase size, brain and body mass, supplemented by our own data from Poland, Germany, and the Czech Republic.

We analysed the effect of geographic and climate variables on the intensity of change and patterns of brain reorganization.

From summer to winter the braincase height decreased by 13%, followed by 10% regrowth in spring.

For body mass the changes were -21%/+82%, respectively. Changes in...