MANDIBULAR SHAPE VARIATION AND ASYMMETRY IN PRAMENKA, AKKARAMAN, AND KANGAL AKKARAMAN SHEEP: A GEOMETRIC MORPHOMETRIC STUDY

Abstract

The aim of this study was to characterise mandibular shape variation and asymmetry patterns in three sheep breeds from two geographical regions: Pramenka from Bosnia and Herzegovina, and Akkaraman and Kangal Akkaraman from Türkiye. Thirty-four male mandibles (10 Pramenka, 12 Akkaraman, 12 Kangal Akkaraman) were analysed by landmark-based geometric morphometrics, with eleven homologous landmarks digitised on lateral photographs. Generalised Procrustes Analysis, Principal Component Analysis (PCA), Discriminant Function Analysis (DFA), allometric regression, and Procrustes ANOVA were performed in MorphoJ. The first three principal components explained 63.37% of total shape variation. In the PCA morphospace, Akkaraman and Kangal Akkaraman specimens overlapped almost completely, whereas Pramenka formed a clearly separated cluster. DFA confirmed significant shape differences in all pairwise comparisons, with cross-validated classification accuracy of 79.2% between the two Anatolian breeds and 100% for both Pramenka comparisons. Shape differences were most pronounced in the pars incisiva, pars molaris, corpus mandibulae, and ramus mandibulae. Centroid size explained only 2.51% of shape variation (P = 0.3467), indicating no significant allometric effect. Fluctuating asymmetry exceeded directional asymmetry for both size and shape; directional asymmetry in shape nevertheless remained statistically significant, consistent with a degree of masticatory laterality.
Mandibular morphology therefore differs primarily between geographically distant breeds, while the two Anatolian breeds remain morphologically close, and the observed asymmetry patterns point to developmental instability as the principal source. These data provide morphometric reference values for future work on breed differentiation, functional adaptation, and zooarchaeological identification of ovine remains.