Size increase without genetic divergence in the Eurasian water shrew Neomys fodiens

• Published in: Scientific reports Vol. 9; no. 1; p. 17375
• Main Authors: Balmori-de la Puente, Alfonso, Nores, Carlos, Román, Jacinto, Fernández-González, Angel, Aymerich, Pere, Gosálbez, Joaquim, Escoda, Lídia, Castresana, Jose
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 22.11.2019; Nature Publishing Group UK
• Subjects: Adaptation; Adaptation, Physiological - physiology; Animal behavior; Animals; Asia; Body Size - physiology; Body Weights and Measures - history; Body Weights and Measures - veterinary; Ecosystem; Endangered & extinct species; Europe; Evolution; Evolution, Molecular; Evolutionary biology; Gene frequency; Genetic analysis; Genetic engineering; Genetic Speciation; History, 20th Century; History, 21st Century; Mitochondria; Mitochondrial DNA; Morphology; Morphometry; Neomys fodiens; Phylogeography; Population; Population genetics; Principal components analysis; Shrews - anatomy & histology; Shrews - genetics; Skull - anatomy & histology; Sorex palustris; Asia; Europe
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-53891-y

When a population shows a marked morphological change, it is important to know whether that population is genetically distinct; if it is not, the novel trait could correspond to an adaptation that might be of great ecological interest. Here, we studied a subspecies of water shrew, Neomys fodiens niethammeri, which is found in a narrow strip of the northern Iberian Peninsula. This subspecies presents an abrupt increase in skull size when compared to the rest of the Eurasian population, which has led to the suggestion that it is actually a different species. Skulls obtained from owl pellets collected over the last 50 years allowed us to perform a morphometric analysis in addition to an extensive multilocus analysis based on short intron fragments successfully amplified from these degraded samples. Interestingly, no genetic divergence was detected using either mitochondrial or nuclear data. Additionally, an allele frequency analysis revealed no significant genetic differentiation. The absence of genetic divergence and differentiation revealed here indicate that the large form of N. fodiens does not correspond to a different species and instead represents an extreme case of size increase, of possible adaptive value, which deserves further investigation.