Two contrasting hypotheses on the relationship between dental character variability and biochemical-genetic diversity: (1) ''influence of developmental homeostasis'' and (2) ''genetic-phenetic variation correlation'' were tested in brown hare Lepus europaeus Pallas, 1778 populations. Interindividual variability (IV) and fluctuating asymmetry (FA) of 12 non-metrical characters of third lower premolars (P-3) as well as allozymic heterozygosity (H) at 13 polymorphic loci was examined in 385 individuals from 19 geographical sampling units (GSU) in Austria. Juveniles and adults were discriminated according to dry eye lens weights. Sex was determined from internal reproductive organs. IV was calculated as the mean standard deviation of the 11 tooth characters in each GSU. GSU-specific FA was calculated as the mean FA of individuals (FA(IN)), where FA(IN) was the percentage of characters found asymmetric in individuals of a GSU. While IV did not show any significant relationship with H at the population level, FA of adults was significantly positively correlated (r(s) = +0.650, p < 0.05) with H. In juveniles a trend (r(s) = +0.399, ns) for such a correlation was apparent too. This finding corresponds to the ''genetic-phenetic variation correlation hypothesis''. Variability, of both character systems is high in populations with high genomic variability, because both character systems concordantly portray gene peal diversity. Both IV and FA was significantly lower in juveniles than in adults. Since no ontogenic changes in P-3 characters were found, this age-specific difference appears to result from selection against juveniles with low P-3 variability (i.e. low genomic diversity). However, H was not lower in juveniles as compared to adults.
