PHENOTYPIC DIVERSITY AND POPULATION-DYNAMICS - ANOTHER LOOK (WITH PARTICULAR REFERENCE TO THE COMMON SHREW SOREX-ARANEUS)

We studied temporal changes in the level of phenotypic diversity, meas ured by the total phenotypic variance for several characters of skull morphology, in two populations of the common shrew Sorer araneus Linna eus, 1758. We compared a population from central Siberia having a high -amplitude four-year cycle with a population from southern Finland hav ing noncyclic dynamics. The level of total phenotypic diversity varied significantly among years in both populations, but was correlated nei ther with density nor with breeding success in either of them. We did, however, find differences between the two populations. When we compar ed changes in the level of phenotypic diversity with changes in the le vel of developmental stability, as measured by chance developmental va riance (fluctuating asymmetry), the cyclic Siberian population exhibit ed increased developmental variability in the peak year, which was ass ociated with relatively small proportion of other sources of variation (and genetic variation in particular). In other years, the role of ch ance variation was less and the proportion of other sources of varianc e was higher. On the other hand, in the noncyclic Finnish population, oscillations in the level of phenotypic diversity were mainly caused b y changes in developmental stability. These results illustrate that no t only dynamics of genotype variety, but also the alterations in the l evel of developmental stability can be of great importance for changes in phenotypic diversity.