Dimorphism in the Skull Form of Golden Jackals (Canis aureus Linnaeus, 1758) in the Western Balkans: A Geometric Morphometric Approach

Marina Piria,Tihomir Florijančić,Andrea Rezic,Massimo Scandura,Piera Lubinu,Nikica Šprem,Ivica Bošković

doi:10.17582/journal.pjz/2017.49.3.989.997

Abstract

Geometric morphometrics analyses are now often used to examine morphological variation in carnivore skull. Differences in golden jackal skull shape and size due to sexual dimorphism were examined using two dimensional geometric morphometrics approach. A total of 21 landmarks described the dorsal side of the skull and lateral side of the mandible. Individual variation in skull and mandible morphology was statistically significant for the shape (p<0.01). Sexual dimorphism as main effect was highly significant for the dorsal skull shape and the mandible shape and size (p<0.01). The comparison of mandible mean shapes using discriminant function analysis and parametric test did not reveal significant differences between the sexes, while dorsal mean skull shape was statistically significant (p<0.05). The shape comparison between males and females using permutation tests with procrustes distance yielded with significant results for both skull and mandible shape. Further studies are required with increased sample size and number of landmarks so as to obtain a more accurate expression of form and better differentiation between the sexes.

Highlights

The difference in body size between the sexes is a common feature of many organisms, from vascular plants to invertebrates and vertebrates, including mammals (Hood, 2000)
This study aims to characterize and quantify sexual form variation in skulls of golden jackal using geometric morphometric methods that are powerful tools in describing and analyzing biological forms (Bookstein, 1991; Adams et al, 2013)
The sources of measurement error such as positioning and digitizing are commonly tested by using an analysis of variance–ANOVA (Viscosi and Cardini, 2011)

Summary

Introduction

The difference in body size between the sexes is a common feature of many organisms, from vascular plants to invertebrates and vertebrates, including mammals (Hood, 2000). The golden jackal is a territorial, medium-sized, generalist carnivore that is widespread in southeastern and central Europe, South Asia and in north-eastern Africa (Šálek et al, 2014). Golden jackal populations are increasing across the northern and western Balkan Peninsula, central Europe and on the Indian Subcontinent, where it holds the status of Least Concern (Katuwal and Dahal, 2013). In Europe, it is distributed in small and scattered populations, mainly along the Mediterranean and Black Sea coasts of the Balkan Peninsula (Giannatos et al, 2005; Krofel, 2008). Expansion of the species started in the early 1980s, when the golden jackal colonized the Istrian Peninsula, expanding its Balkan range due likely to the strong increase of its Dalmatian and Bulgarian populations (Lapini et al, 2009). In Greece, its population has been declining over the past three decades (Krofel, 2008)

Objectives

Methods

Results

Conclusion