Cranial variability of the Serbian golden jackal: Geographic variation, sexual dimorphism and allometry

Geometric morphometric approaches were employed for the first time to explore skull size and shape changes in golden jackal (Canis aureus) from Serbia. We examined three different, but connected aspects of its cranial variability: geographic variation, sexual dimorphism and allometry. To elucidate the pattern of cranial size and shape variation, we analyzed ventral crania of subadults and adults from two geographic regions of Serbia. For both age groups there were no significant size, but significant shape differences between golden jackals from northeastern and central Serbia. The observed shape differences were subtle, probably due to recent range expansion of this species in the Balkans and a strong founder effect in the newly established populations. The detected significant sexual size and shape dimorphisms (SSD and SShD) were slight and more evident in adult crania. Although the SShD observed in adult crania is influenced by SSD, factors responsible for the non-allometric component of shape variation, and not pure size differences between sexes, are those that are most important for generation of SShD in this species. A monogamous reproductive system, male parental care, omnivorous and opportunistic feeding behavior and the absence of division of labor between males and females in activities other than parental care, could all be related to the driving of morphological similarity between the sexes.