VARIATION IN THE SHAPE PATTERN OF MOLARS IN POPULATIONS OF THE BANK VOLE (CLETHRIONOMYS-GLAREOLUS SCHREB)

The shapes of the enamel pattern on M1 and M3 molar occlusal surfaces were examined to determine their variation in seven bank vole (Clethri onomys glareolus) populations in the Danube River alluvium and in sout hern Moravia. Three and five different patterns in the M1 and M3 molar s, respectively, were discriminated bilaterally, using both-sided mand ibles (n = 6865) and maxillae (n = 6600) in analysis. There was no dif ference in the proportion of a particular pattern between males and fe males; however, differences were found for animals differing in age. C luster analysis revealed good similarities of the age classes ranging from 1 to 5 months in the case of M1 molar, and of the age classes fro m 1 to 11 months in the case of M3 molar. In a population, proportions of the patterns varied from year to year, independent of density of t he voles. There were local differences in proportions for different ha bitats in the same locality. We conclude that the shape pattern of M1 and M3 is a useful non-metrical character to study genetic divergence among populations; however, this is so only when the samples are suffi ciently large and a defined portion of age group is used.