Morphological Diversity of the Skull and Lower Jaw of Three Species of Shrews (Eulipotyphla, <i>Sorex</i>) During Depressions and Peaks of Abundance

Abstract

Ecological conditions can influence the individual development of organisms and morphological variability at the population level. The dimensions and proportions of the skull and lower jaw of immature shrews (Sorex araneus, S. caecutiens, S. minutus) captured in August in overgrown clearings in the middle taiga of north-eastern Europe were dependent on the stage of abundance (“pikes” or “depressions”). For all three species belonging to the same taxocenosis, a statistically significant decrease in skull and jaw measurements was observed against a background of high abundance in captures, and multidimensional morphological niches corresponding to different stages were significantly separated. The parameters of morphological diversity - entropy and a measure of self-organisation were depended on the amplitude of fluctuations in species occurrence, but varied within limits characteristic of mammals. Together with Dehnel’s phenomenon, natural population fluctuations may be one of the main factors determining the nature of the dynamics of individual development and the spatio-temporal variability of morphological diversity in shrews.