Fifty years of data show the effects of climate on overall skull size and the extent of seasonal reversible skull size changes in the common shrew

Abstract

1. Global climate change affects many aspects of biology and has been shown to cause body size changes in animals. However, suitable datasets allowing the analysis of long-term relationships between body size and climate are rare. 2. The size of the skull, often used as a proxy for body size, does not change much in fully grown vertebrates, but some soricine shrews shrink their skull and brain in winter and regrow it in spring. This is thought to be a winter adaptation in these high-metabolic, nonhibernating animals, as a smaller brain size reduces energy requirements. 3. Climate could thus affect not only the overall size but also the pattern of the size change, i.e., Dehnel’s Phenomenon, in these shrews. 4. We assessed the impact of the changes in climate on the overall skull size and the different stages of Dehnel’s phenomenon in skulls of the common shrew, Sorex araneus, collected over 50 years in the Białowieża Forest, NE Poland. 5. Overall skull size decreased, along with increasingly mild winters and decreasing soil moisture, which determined the availability of the shrews’ main food source, earthworms. The magnitude of Dehnel’s phenomenon increased over time, indicating an increasing selection pressure on animals in winter. Overall, climate clearly affected the common shrew’s overall size as well as its seasonal size changes. With the current acceleration in climate change, the effects on the distribution range of this cold-adapted species may be quite severe.

Shrews Under-Represented in Fruit Farms and Homesteads

“…Insectivores are not listed as pests; therefore, they are rarely monitored [ 43 ]. As with other mammals, climate change [ 44 ] is an important factor influencing the distribution and biology of shrews [ 45 , 46 ]. In agricultural habitats, shrews are very important as model species, as they are more likely to be contaminated by various compounds used as insecticides, plant protection products, etc., and, consequently, they show higher contamination levels [ 47 ].…”

Morphospace dynamics and intraspecies variety of Sorex araneus and S. tundrensis according to recent and fossil data

“…The common shrew is the most popular research subject in different aspects of evolutionary biology, adaptation, and speciation (see reviews by several authors, e.g., Polly, 2019;Thaw et al, 2019;Taylor et al, 2022) just as the house mouse model (Zima and Searl, 2019). Intensive investigations in the last three decades have revealed high levels of pheno-typic and genotypic polymorphisms among recent samples of the common shrew (Searle and Wójcik, 1998;Polly, , 2005Polly, , 2007Wójcik et al, 2003;Mishta and Searle, 2019;White et al, 2019;Zima and Searl, 2019).…”