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Cranial variability and differentiation among golden jackals (Canis aureus) in Europe, Asia Minor and Africa - PubMed

  • ️Wed Jan 01 2020

Cranial variability and differentiation among golden jackals (Canis aureus) in Europe, Asia Minor and Africa

Stoyan Stoyanov. Zookeys. 2020.

Abstract

Golden jackal (Canis aureus) expansion in the last decades has triggered research interest in Europe. However, jackal phylogeny and taxonomy are still controversial. Morphometric studies in Europe found differences between Dalmatian and the other European jackals. Recent genetic studies revealed that African and Eurasian golden jackals are distinct species. Moreover, large Canis aureus lupaster may be a cryptic subspecies of the African golden jackal. Although genetic studies suggest changes in Canis aureus taxonomy, morphological and morphometric studies are still needed. The present study proposes the first comprehensive analysis on a wide scale of golden jackal skull morphometry. Extensive morphometric data of jackal skulls from Europe (including a very large Bulgarian sample), Asia Minor, and North Africa were analysed, by applying recently developed statistical tools, to address the following questions: (i) is there geographic variation in skull size and shape among populations from Europe, Anatolia and the Caucasus?, (ii) is the jackal population from the Dalmatian coast different?, and (iii) is there a clear distinction between the Eurasian golden jackal (Canis aureus) and the African wolf (Canis lupaster sensu lato), and among populations of African wolves as well? Principal component analysis and linear discriminant analysis were applied on the standardized and log-transformed ratios of the original measurements to clearly separate specimens by shape and size. The results suggest that jackals from Europe, Anatolia and the Caucasus belong to one subspecies: Canis aureus moreotica (I. Geoffroy Saint-Hilaire, 1835), despite the differences in shape of Dalmatian specimens. The present study confirmed morphometrically that all jackals included so far in the taxon Canis aureus sensu lato may represent three taxa and supports the hypothesis that at least two different taxa (species?) of Canis occur in North Africa, indicating the need for further genetic, morphological, behavioural and ecological research to resolve the taxonomic uncertainty. The results are consistent with recent genetic and morphological studies and give further insights on golden jackal taxonomy. Understanding the species phylogeny and taxonomy is crucial for the conservation and management of the expanding golden jackal population in Europe.

Keywords: C. anthus; C. aureus; C. aureus moreotica; C. lupaster; Canid; morphology; skull morphometry; taxonomy.

Stoyan Stoyanov.

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Figures

Figure 1.
Figure 1.

Map of Eurasian golden jackal range (Hoffmann et al. 2018) and African wolf range (Hoffmann and Atickem 2019) based on IUCN Red List data. Sample localities (countries) and number of measured specimens are shown. Note: The range map of Eurasian golden jackal from IUCN Red List has not been updated since 2008. The confirmed presence of jackals in Poland, Denmark, Netherlands and Baltic countries is not shown.

Figure 2.
Figure 2.

Skull measurements employed in the analyses (following von den Driesch 1976): condylobasal length (Cbl), greatest length of the nasals (Nasl), length of the carnassial (P4), measured at the cingulum (Lp4), greatest diameter of the auditory bulla (Bull), greatest breadth of the braincase (Skb), zygomatic breadth (Zyg), least breadth at the postorbital constriction (Pob), frontal breadth (Fb), least breadth between the orbits (Iob), greatest palatal breadth (Palb), least palatal breadth (Rb), skull height (Skh), total length of the mandible (Mand) and length of the carnassial (M1), measured at the cingulum (Mlm1). ACanis cranium, dorsal view BCanis cranium, left side view CCanis cranium, basal view DCanis mandible, left side, lateral view ECanis upper and lower carnassial (P4 and M1).

Figure 3.
Figure 3.

Principal component analysis. Separation between taxonomic groups along isometric size and first principal components in shape space. Ellipses show 95 % confidence interval for each group. Specimens of Canis aureus are divided in two groups – Europe and Asia Minor, and Croatia (the Dalmatian coast). A country origin of European specimens is marked with different symbols B country origin of African specimens is presented.

Figure 4.
Figure 4.

Principal component analysis. The first two principal components in shape space account for 53.6 % of the variance. Ellipses show 95 % confidence interval for each group. Specimens of Canis aureus are divided in two groups – Europe and Asia Minor, and Croatia (the Dalmatian coast). A separation between taxonomic groups along isometric size and second principal component B separation between taxonomic groups along first two principal components in shape space.

Figure 5.
Figure 5.

PCA ratio spectrum for the first and second principal component in shape space of the 14 craniodental measurements. See Material and methods and Figure 2 caption for the definition of the craniodental measurements.

Figure 6.
Figure 6.

Allometry ratio spectrum of the 14 craniodental measurements used in this study. See Material and methods and Figure 2 caption for the definition of the craniodental measurements.

Figure 7.
Figure 7.

Separation of groups by LDAA three taxonomic groups were included in the analysis: Eurasian golden jackals, African golden jackals and African wolves B specimens from Dalmatia were included in the analysis as a separate group.

Figure 8.
Figure 8.

The ratios that best separated taxon groups revealed by the LDA ratio extractor. The measure δ indicates how well shape discriminates in relation to size. A value of δ close to unity means that separation is mainly due to size, whereas a value close to zero indicates separation is mainly due to shape.

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