Author ORCID Identifier
William R. Thomas: 0009-0002-3858-2440
Tanya M. Lama: 0000-0002-7372-8081
Cecilia Baldoni: 0009-0008-1341-9456
Laia Marín-Gual: 0000-0003-1480-0976
Diana Moreno Santillán: 0000-0003-2153-0732
Marta Farré: 0000-0001-9170-5767
Linelle Abueg: 0000-0002-6879-3954
Jennifer Balacco: 0000-0001-7102-1632
Olivier Fedrigo: 0000-0002-6450-7551
Giulio Formenti: 0000-0002-7554-5991
Nivesh Jain: 0000-0002-8134-2904
Jacquelyn Mountcastle: 0000-0003-1078-4905
Tatiana Tilley: 0009-0001-9277-7743
Ying Sims: 0000-0003-4765-4872
Alan Tracey: 0000-0002-4805-9058
Jo Wood: 0000-0002-7545-2162
David A. Ray: 0000-0002-3340-3987
Dominik Von Elverfeldt: 0000-0002-6219-3528
John Nieland: 0000-0001-7423-0122
Angelique P. Corthals: 0000-0002-5610-2992
Aurora Ruiz-Herrera: 0000-0003-3868-6151
Dina K.N. Dechmann: 0000-0003-0043-8267
Erich Jarvis: 0000-0001-8931-5049
Liliana M. Dávalos: 0000-0002-4327-7697
Document Type
Article
Publication Date
2-1-2026
Publication Title
Molecular Biology and Evolution
Abstract
Sorex araneus, the Eurasian common shrew, has seasonal brain size plasticity (Dehnel's phenomenon) and many intraspecific chromosomal rearrangements. Genomic contributions to these traits, however, remain unknown. We couple a chromosome-scale genome assembly with seasonal brain transcriptomes to discover relationships between molecular evolution and both traits. While Positively Selected Genes (PSGs) enriched the Fanconi anemia DNA repair pathway (FANCI, FAAP100), which is likely involved in chromosomal rearrangements by preventing the accumulation of chromosomal aberrations, genes under positive selection or showing seasonal differential expression in the brain implicate neurogenesis (PCDHA6, SOX9, Notch signaling) and metabolic regulation (VEGFA, SPHK2) as key mechanisms underlying Dehnel's phenomenon. We also find that both positively selected and differentially expressed genes in the hippocampus are overrepresented near S. araneus evolutionary breakpoints. This relates both positive selection and differential expression to accessible chromatin configuration, suggesting that chromosomal rearrangements are integral to adaptive evolution and the regulation of brain size plasticity.
Keywords
chromosomal evolution, cortex, Dehnel’s phenomenon, evolutionary breakpoints, highly contiguous genome assembly, hippocampus, shrew
Volume
43
Issue
2
DOI
https://doi.org/10.1093/molbev/msag006
ISSN
07374038
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License
Rights
© The Author(s) 2026
Version
Version of Record
Recommended Citation
Thomas, William R.; Lama, Tanya M.; Baldoni, Cecilia; Marín-Gual, Laia; Moreno Santillán, Diana; Farré, Marta; Abueg, Linelle; Balacco, Jennifer; Fedrigo, Olivier; Formenti, Giulio; Jain, Nivesh; Mountcastle, Jacquelyn; Tilley, Tatiana; Sims, Ying; Tracey, Alan; Wood, Jo; Ray, David A.; Von Elverfeldt, Dominik; Nieland, John; Corthals, Angelique P.; Ruiz-Herrera, Aurora; Dechmann, Dina K.N.; Jarvis, Erich; and Dávalos, Liliana M., "Genomic Comparisons and the Adaptive Basis of Brain Size Plasticity and Chromosomal Instability in the Eurasian Common Shrew" (2026). Biological Sciences: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/bio_facpubs/335