DEVELOPMENTAL STABILITY AND POPULATION-DYNAMICS OF SHREWS SOREX IN CENTRAL SIBERIA

We examined temporal variation in developmental stability measured by fluctuating asymmetry of 10 skull characters in sympatric populations of three shrew species: Sorer araneus Linnaeus, 1758, S. caecutiens La xmann, 1788 and S. tundrensis Merriam, 1900 from one locality in centr al Siberia with a high four-year-cycle of small mammals. Simultaneous significant changes in developmental stability have been revealed duri ng a population cycle 1986-1989 for all three, most abundant shrew spe cies in the locality. The highest asymmetry for all these species occu rred in the year of maximal density. Similar high asymmetry was found for the separate samples of two other species: S. roboratus Hollister, 1913 and S. isodon Turov, 1924, collected in a peak year 1989 only. T he maximal density in 1989 corresponded to the lowest level of breedin g success and developmental stability and, vice versa, minimal density in 1986 was accompanied by the highest level of breeding success and developmental stability. These data suggest that overpopulation caused by high density of various small mammals adversely affects an organis m's condition. Thus, developmental stability may be used to monitor po ssible changes in a population even in cases where direct estimation o f fitness is difficult.