CAN SHREWS AVOID COMPETITION WHEN VIOLATING THE HUTCHINSON’S ECOLOGICAL RULE?

It is established that the rule of G. Hutchinson’s idea of the ratio of body weight and size and foraging organs of similar species is not fully respected when comparing the species of shrews of the genus Sorex. The similarity of the centroid sizes of the mandible of large species S. isodon and S. araneus was revealed. By methods of geometric morphometrics, differences in the shape of the mandible, which is actively used in foraging, have been established between the species. Interspecific differences in mandibular indices reflecting trophic specialization and functional features of mandibles were found. Therefore, shrews can avoid competition even if Hutchinson’s rule is violated, and not so much due to the size, but due to the transformation of the lower jaw, its specialization, methods of capturing prey and changing the diet. Consequently, Hutchinson’s ecological rule is not mandatory, but only one of the conditions for reducing competition between closely related species.