NONMETRICAL POLYMORPHISM OF THE FIRST LOWER PREMOLAR (P-3) IN AUSTRIAN BROWN HARES (LEPUS-EUROPAEUS) - A STUDY ON REGIONAL DIFFERENTIATION

The pattern of the occlusal surface of 1018 first Lower premolars (P-3 ) was studied in 527 brown hares (Lepus europaeus) collected in 1988 a nd 1989 at 21 localities in Austria. In total, 29 variants were descri bed. For analysis of geographic variation in the P-3-pattern, the loca lity samples were grouped into five regional units with respect to spa tial distances and putative barriers for gene how. From the primarily encountered variants, 15 dichotomized characters were created and thei r frequencies within the five regional units were calculated. Strong r ight/left dependencies of character states suggested a high degree of bilateral symmetry in each character. In contrast, characters varied l argely independently from one another. This indicated the absence of c omplex types of the Ps. One character showed sex-dependence but no age dependence was found. Intraregional differences in trait frequency we re found in one character. Non-metrical morphological divergence among the five regional units was revealed by using C. A. B. Smith's 'mean measure of divergence' and 'percentage dissimilarity' as distance meas urements. Six pairwise morphological distances differed significantly from zero. Phenetic affinities among the five populations showed good correspondence to the geographic distribution of the samples. However, whereas the alpine chains of mountains appeared to separate the hare populations, the River Danube did not. Generally, good concordance was found between the current pattern of phenetic differentiation and ear lier results of cluster analyses using non-metrical skull traits and a llozymes of the same populations. This suggested that geographic diffe rentiation of the P-3-traits was largely due to random historical rath er than to ecogenetic causes. Nevertheless, in one population the stri king discordance between the three character-systems compared could in dicate some influence of a selection pressure on certain P-3-variants.