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

Suitability of red fox (Vulpes vulpes) and golden jackal (Canis aureus) as hosts of Echinococcus multilocularis based on egg production characteristics and literature data on the intestinal ecosystems of carnivores

Echinococcus multilocularis is the most important food-borne parasite in Europe. Its natural definitive host is the red fox (Vulpes vulpes) while other canid species play a secondary role in the maintenance of its endemics. However, recent studies call attention to the potential of golden jackal (Canis aureus) as a suitable definitive host for E. multilocularis. Our study aimed to evaluate the quantitative and qualitative egg production traits of adult E. multilocularis in different hosts as an indicator of reproductive success. Investigation of 111 and 82 parasites from 33 red foxes and 29 golden jackals, respectively, we ascertained that the proportion of worms with mature eggs was significantly lower in golden jackals than in red foxes. Those worms, which produced mature eggs in golden jackal hosts, originated from less crowded infrapopulations than their fox-originated counterparts. Other characteristics of the parasite's reproductive ability, such as the proportion of fertile worms, and mean egg production were similar in the two hosts. Comparing these findings to evolutionary data on different canid taxa, we hypothesised that the mutual presence of red fox and a differently evolved host of E. multilocularis might contribute to the formation of stable parasite circulation in these multi-host systems.

Virtual reconstruction of the Canis arnensis type (Canidae, Mammalia) from the Upper Valdarno Basin (Italy, Early Pleistocene)

Taphonomic deformation, whether it be brittle or plastic, is possibly the most influential process hindering the correct understanding of fossil species morphology. This is especially true if the deformation affects type specimens or applies to or obscures taxonomically diagnostic or functionally significant traits. Target Deformation, a recently developed virtual manipulation protocol, was implemented to address this issue by applying landmark-guided restoration of the original, deformed fossils, using undeformed specimens (or parts thereof) of the same species as a reference. The enigmatic Early Pleistocene canid Canis arnensis provides a typical example of a fossil species in dire need of virtual restoration. Its lectotype specimen is heavily deformed and none of the few known skulls are well preserved, obscuring the recognition of its systematic and phylogenetic position. Our results indicate that the algorithm effectively countered the lectotype skull's laterolateral compression and its concomitant rostrocaudal elongation. Morphometrically, comparison of the retrodeformed cranium (IGF 867_W) with other specimens of the same species, and to other fossil and extant canid material, confirms IGF 867_W consistently clusters within C. arnensis variability. Overall, the evidence presented here confirms that Target Deformation provides a powerful tool to better characterize complex taxa like C. arnensis, whose knowledge is severely affected by the state of preservation of its fossil material.

Possible origins and implications of atypical morphologies and domestication-like traits in wild golden jackals (Canis aureus)

Deciphering the origins of phenotypic variations in natural animal populations is a challenging topic for evolutionary and conservation biologists. Atypical morphologies in mammals are usually attributed to interspecific hybridisation or de-novo mutations. Here we report the case of four golden jackals (Canis aureus), that were observed during a camera-trapping wildlife survey in Northern Israel, displaying anomalous morphological traits, such as white patches, an upturned tail, and long thick fur which resemble features of domesticated mammals. Another individual was culled under permit and was genetically and morphologically examined. Paternal and nuclear genetic profiles, as well as geometric morphometric data, identified this individual as a golden jackal rather than a recent dog/wolf-jackal hybrid. Its maternal haplotype suggested past introgression of African wolf (Canis lupaster) mitochondrial DNA, as previously documented in other jackals from Israel. When viewed in the context of the jackal as an overabundant species in Israel, the rural nature of the surveyed area, the abundance of anthropogenic waste, and molecular and morphological findings, the possibility of an individual presenting incipient stages of domestication should also be considered.

The complete mitochondrial genome and phylogenetic characterization of two putative subspecies of golden jackal (Canis aureus cruesemanni and Canis aureus moreotica)

The golden jackal (Canis aureus) is a canid species found across southern Eurasia. Several subspecies of this animal have been genetically studied in regions such as Europe, the Middle East, and India. However, one subspecies that lacks current research is the Indochinese jackal (Canis aureus cruesemanni), which is primarily found in Southeast Asia. Using a genome skimming approach, we assembled the first complete mitochondrial genome for an Indochinese jackal from Thailand. To expand the number of available Canis aureus mitogenomes, we also assembled and sequenced the first complete mitochondrial genome of a golden jackal from Turkey, representing the C. a. moreotica subspecies. The mitogenomes contained 37 annotated genes and are 16,729 bps (C. a. cruesemanni) and 16,669 bps (C. a. moreotica) in length. Phylogenetic analysis with 26 additional canid mitogenomes and analyses of a cytochrome b gene-only data set together support the Indochinese jackal as a distinct and early-branching lineage among golden jackals, thereby supporting its recognition as a possible subspecies. These analyses also demonstrate that the golden jackal from Turkey is likely not a distinct lineage due to close genetic relationships with golden jackals from India and Israel.

Mismatch between IUCN range maps and species interactions data illustrated using the Serengeti food web

Background

Range maps are a useful tool to describe the spatial distribution of species. However, they need to be used with caution, as they essentially represent a rough approximation of a species' suitable habitats. When stacked together, the resulting communities in each grid cell may not always be realistic, especially when species interactions are taken into account. Here we show the extent of the mismatch between range maps, provided by the International Union for Conservation of Nature (IUCN), and species interactions data. More precisely, we show that local networks built from those stacked range maps often yield unrealistic communities, where species of higher trophic levels are completely disconnected from primary producers.

Methodology

We used the well-described Serengeti food web of mammals and plants as our case study, and identify areas of data mismatch within predators' range maps by taking into account food web structure. We then used occurrence data from the Global Biodiversity Information Facility (GBIF) to investigate where data is most lacking.

Results

We found that most predator ranges comprised large areas without any overlapping distribution of their prey. However, many of these areas contained GBIF occurrences of the predator.

Conclusions

Our results suggest that the mismatch between both data sources could be due either to the lack of information about ecological interactions or the geographical occurrence of prey. We finally discuss general guidelines to help identify defective data among distributions and interactions data, and we recommend this method as a valuable way to assess whether the occurrence data that are being used, even if incomplete, are ecologically accurate.

Maybe So, Maybe Not: Canis lepophagus at Hagerman Fossil Beds National Monument, Idaho, USA

A canid dentary is described from the Pliocene Glenns Ferry Formation at Hagerman Fossil Beds National Monument, south-central Idaho, USA. The specimen possesses traits in alliance with and measurements falling within or exceeding those of Canis lepophagus. The dentary, along with a tarsal IV (cuboid) and an exploded canine come from the base of the fossiliferous Sahara complex within the monument. Improved geochronologic control provided by new tephrochronologic mapping by the U.S. Geological Survey-National Park Service Hagerman Paleontology, Environments, and Tephrochronology Project supports an interpolated age of approximately 3.9 Ma, placing it in the early Blancan North American Land Mammal Age. It is conservatively referred to herein as Canis aff. C. lepophagus with the caveat that it is an early and robust example of that species. A smaller canid, initially assigned to Canis lepophagus and then to Canis ferox, is also known from Hagerman. Most specimens of Canis ferox, including the holotype, were recently reassigned to Eucyon ferox, but specimens from the Hagerman and Rexroad faunas were left as Canis sp. and possibly attributed to C. lepophagus. We agree that these smaller canids belong in Canis and not Eucyon but reject placing them within C. lepophagus; we refer to them here as Hagerman-Rexroad Canis. This study confirms the presence of two approximately coyote-sized canids at Hagerman and adds to the growing list of carnivorans now known from these fossil beds.

The canine counts! Significance of a craniodental measure to describe sexual dimorphism in canids: Golden jackals (Canis aureus) and African wolves (Canis lupaster)

Sexual dimorphism is a widespread phenomenon among mammals, including carnivorans. While sexual dimorphism in golden jackals (Canis aureus) has been analysed in the past, in the related and apparently convergent canid, the African wolf (Canis lupaster), it is poorly studied and showed to be relatively small. Previously, sexual size dimorphism (SSD) research in these species was mostly based on skull and body measurements. In our study, we also included dental measurements, namely the diameter of the canine. We used 11 measured sections of 104 adult specimens, comprising 61 golden jackal and 43 African wolf skulls. Data analyses were carried out through logistic regression and conditional inference trees (CIT). To compare the results of SSD to other species, sexual dimorphism indices (SDI) were calculated. Golden jackals and African wolves show significant sexual size dimorphism, both in cranial and dental size. The logistic regression revealed that the mesiodistal diameter of the upper canine is most effective in discerning the sexes. The difference in the calculated SDI of the canine diameter between the sexes amounted to 8.71 in golden jackals and 14.11 in African wolves, respectively—with regional diversity. Thus, the canine diameter is an important measure to investigate SSD as well as an easy tool to apply in the field.

Morphometric variation in wolves and golden jackal in India (Mammalia, Carnivora)

Species of Canis (Carnivora, Canidae) have similar morphology and distinguishing sympatric species is challenging. We present data on morphometry of skull, body and hair of three wild Canis species that occur in India, which include two wolves (Indian wolf, Canislupuspallipes; and Himalayan wolf, Canishimalayensis) and the golden jackal (Canisaureus). A total of 20 cranial and six body measurements and microscopic characteristics of guard hair were analysed, using multivariate ordination to differentiate between species. Cranial measures of the Himalayan wolves were found to be the largest followed by Indian wolves and golden jackals. However, many measures overlapped amongst the three species. Two Principal Components each, for body measures and cranial measures, explained 86 and 91% of the variation in the data, respectively. These Components discriminated the two wolves from golden jackals, but could not distinguish between wolves. Hair medullary patterns were simple and wide type, whereas hair cuticular patterns showed crenate scale margins, near scale distance and irregular wavey scale patterns for all Canis taxa and were not useful to distinguish species. Data reported in this study further contribute to the existing global data on wild canids for a holistic understanding of the variation within the genus and show that distinguishing between all sympatric species from morphology alone may not be possible.

Positive selection on the MHC class II DLA-DQA1 gene in golden jackals (Canis aureus) from their recent expansion range in Europe and its effect on their body mass index

Background

In Europe, golden jackals (Canis aureus) have been expanding their range out of the southern and southeastern Balkans towards central Europe continually since the 1960s. Here, we investigated the level of functional diversity at the MHC class II DLA-DQA1 exon 2 in golden jackal populations from Bulgaria, Serbia, and Hungary. Specifically, we tested for positive selection on and geographic variation at that locus due to adaptation to supposedly regionally varying pathogenic landscapes. To test for potential fitness effects of different protein variants on individual body condition, we used linear modeling of individual body mass indexes (bmi) and accounted for possible age, sex, geographical, and climatic effects. The latter approach was performed, however, only on Serbian individuals with appropriate data.

Results

Only three different DLA-DQA1 alleles were detected, all coding for different amino-acid sequences. The neutrality tests revealed no significant but positive values; there was no signal of spatial structuring and no deviation from the Hardy–Weinberg equilibrium across the studied range of expansion. However, we found a signal of trans-species polymorphism and significant test results for positive selection on three codons. Our information-theory based linear modeling results indicated an effect of ambient temperature on the occurrence of individual DLA-DQA1 genotypes in individuals from across the studied expansion range, independent from geographical position. Our linear modeling results of individual bmi values indicated that yearlings homozygous for DLA-DQA1*03001 reached values typical for adults contrary to yearlings carrying other genotypes (protein combinations). This suggested better growth rates and thus a possible fitness advantage of yearlings homozygous for DLA-DQA1*03001.

Conclusions

Our results indicate a demographic (stochastic) signal of reduced DLA-DQA1 exon 2 variation, in line with the documented historical demographic bottleneck. At the same time, however, allelic variation was also affected by positive selection and adaptation to varying ambient temperature, supposedly reflecting geographic variation in the pathogenic landscape. Moreover, an allele effect on body mass index values of yearlings suggested differential fitness associated with growth rates. Overall, a combination of a stochastic effect and positive selection has shaped and is still shaping the variation at the studied MHC locus.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12862-021-01856-z.

Consequences of the misidentification of museum specimens: the taxonomic status of Canis lupaster soudanicus

Researchers are increasingly using museum collections for taxonomy, systematics, phylogenetics, and faunal analyses, and they assume that taxonomic identifications on museum labels are correct. However, identifications may be incorrect or out of date, which could result in false conclusions from subsequent research. A recent geometric morphometrics analysis of skulls of African canids by Machado and Teta (2020) suggested that Canis lupaster soudanicus is a junior synonym of Lupulella adusta. However, the holotype of soudanicus was not measured and further investigation of the putative soudanicus specimens used in this study showed that these originally were identified as L. adusta. This original identification was confirmed by dental measurements, which also confirm that the holotype of soudanicus is Canis lupaster. Hence, soudanicus should not be synonymized with L. adusta. This example highlights the importance of careful checking of species identifications of museum specimens prior to research and, where possible, including (holo)types of taxa, before making taxonomic changes that could have important consequences for species conservation and management.