loading page

Geographical patterns in seasonal changes of body mass, skull and brain size of common shrews
  • +4
  • Javier Lázaro,
  • Lucie Nováková,
  • Moritz Hertel,
  • Jan Taylor,
  • Marion Muturi,
  • Karol Zub,
  • Dina Dechmann
Javier Lázaro
Max Planck Institute of Animal Behavior
Author Profile
Lucie Nováková
Charles University Faculty of Science
Author Profile
Moritz Hertel
Max-Planck-Institute for Ornithology
Author Profile
Jan Taylor
University of Bialystok
Author Profile
Marion Muturi
Max Planck Institute of Animal Behavior
Author Profile
Karol Zub
Polish Academy of Sciences Mammal Research Institute
Author Profile
Dina Dechmann
Max Planck Institute of Animal Behavior
Author Profile

Abstract

1. Some small mammals exhibit Dehnel’s phenomenon, a drastic decline in body mass, braincase and brain size from summer to winter, followed by a 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 magnitude of change varies between locations as the phenomenon is thought to lead to energy savings during winter. 2. Here we explored geographic variation of the intensity of Dehnel’s phenomenon in Sorex araneus. We compiled the literature on seasonal changes in braincase size, brain and body mass, supplemented by our own data from Poland, Germany and Czech Republic. 3. We analysed the effect of geographic and climate variables on the magnitude of change and patterns of brain reorganization. 4. 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 increased along the north-east axis. Several climate variables were correlated with these transformations, confirming a link of the magnitude of the changes with environmental conditions. This relationship differed for the brain mass decline vs. regrowth, suggesting that they may have evolved under different selective pressures. 5. We found no geographic trends explaining variability in the brain mass changes although they were similar (-21%/+10%) to those of the braincase size. Underlying patterns of change in brain organisation in North-Eastern Poland were almost identical to the pattern observed in Southern Germany. This indicates that local habitat characteristics may play a more important role in determining brain structure than broad scale geographic conditions. 6. We discuss the techniques and criteria used for studying this phenomenon, as well as its potential presence in other taxa and the importance of distinguishing it from other kinds of seasonal variation.

Peer review status:UNDER REVIEW

05 Jun 2020Submitted to Ecology and Evolution
06 Jun 2020Assigned to Editor
06 Jun 2020Submission Checks Completed
25 Jun 2020Reviewer(s) Assigned