Seasonal brain size changes in the common shrew

Abstract For our German-Polish collaborative project, we search for an PhD student interested in the interface between evolution, energetics, neurobiology, and behavior. In our project we investigate the "Dehnel Phenomenon" in the common shrew Sorex aranaeus. These high-metabolic animals, who are active year-round and almost constantly have to search for food, shrink 20-30% in winter and then regain their size and weight in spring. This includes the braincase and the brain itself. The shrinkage is not due to fat or water loss, and not explained by cell death and neurogenesis either. Shrinkage and re-growth in spring is also found in most of the other organs and bone matter.
The scope of the project is kept deliberately broad here, as we would welcome a potential students’ input regarding the focus of her/his project. This is a joint project with Moritz Hertel, MPIO Seewiesen, and Jan Taylor, University of Bialystok.
We want to explore this phenomenon from various angles possibly including the following:

  • Histology: What actually changes in the brain (which regions are most affected and what happens on a cellular-level), and what can we learn from this about the conditions inducing the size change and the underlying evolutionary pressures?
  • Experiments: Can we induce the phenomenon in captive animals to learn more about the triggers?
  • Behavioral observations: What are the consequences for the animals in standard lab experiments and in the field?
  • Metabolism: The most obvious reason are metabolic constraints, but then why do the animals shrink in winter (contradicting the Bergmann's rule) and what behavioral changes are observed as reason or consequence of this?
  • Comparative approach: by comparing populations in Poland and Germany we can infer the role of climate, day length, etc. on the phenomenon.

Keywords Dehnel's phenomenon, neurobiology, ecology, metabolism

Main advisor Dina Dechmann, MPIO Radolfzell

Interested in this PhD project? Apply here!

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