Molecular and evolutionary history of melanism in North American gray wolves

Heterozygosity is low where rare color variants in wild carnivores prevail

Coat color and pattern are a distinguished feature in mammalian carnivores, shaped by climatic cycles and habitat type. It can be expressed in various ways, such as gradients, polymorphisms, and rare color variants. Although natural selection explains much of the phenotypic variation found in the wild, genetic drift and heterozygote deficiency, as prominent in small and fragmented populations, may also affect phenotypic variability through the fixation of recessive alleles. The aim of this study was to test whether rare color variants in the wild could relate to a deficiency of heterozygotes, resulting from habitat fragmentation and small population size. We present an overview of all rare color variants in the order Carnivora, and compiled demographic and genetic data of the populations where they did and did not occur, to test for significant correlations. We also tested how phylogeny and body weight influenced the presence of color variants with phylogenetic generalized linear mixed models (PGLMMs). We found 40 color-variable species and 59 rare color variants. In 17 variable phenotypic populations for which genetic diversity was available, the average A R was 4.18, H O = 0.59, and H E = 0.66, and F IS = 0.086. We found that variable populations displayed a significant reduction in heterozygosity and allelic richness compared to non-variable populations across species. We also found a significant negative correlation between population size and inbreeding coefficients. Therefore, it is possible that small effective size had phenotypic consequences on the extant populations. The high frequency of the rare color variants (averaging 20%) also implies that genetic drift is locally overruling natural selection in small effective populations. As such, rare color variants could be added to the list of phenotypic consequences of inbreeding in the wild.

Hidden in the sand: Phylogenomics unravel an unexpected evolutionary history for the desert-adapted vipers of the genus Cerastes

The desert vipers of the genus Cerastes are a small clade of medically important venomous snakes within the family Viperidae. According to published morphological and molecular studies, the group is comprised by four species: two morphologically similar and phylogenetically sister taxa, the African horned viper (Cerastes cerastes) and the Arabian horned viper (Cerastes gasperettii); a more distantly related species, the Saharan sand viper (Cerastes vipera), and the enigmatic Böhme's sand viper (Cerastes boehmei), only known from a single specimen in captivity allegedly captured in Central Tunisia. In this study, we sequenced one mitochondrial marker (COI) as well as genome-wide data (ddRAD sequencing) from 28 and 41 samples, respectively, covering the entire distribution range of the genus to explore the population genomics, phylogenomic relationships and introgression patterns within the genus Cerastes. Additionally, and to provide insights into the mode of diversification of the group, we carried out niche overlap analyses considering climatic and habitat variables. Both nuclear phylogenomic reconstructions and population structure analyses have unveiled an unexpected evolutionary history for the genus Cerastes, which sharply contradicts the morphological similarities and previously published mitochondrial approaches. Cerastes cerastes and C. vipera are recovered as sister taxa whilst C. gasperettii is a sister taxon to the clade formed by these two species. We found a relatively high niche overlap (OI > 0.7) in both climatic and habitat variables between C. cerastes and C. vipera, contradicting a potential scenario of sympatric speciation. These results are in line with the introgression found between the northwestern African populations of C. cerastes and C. vipera. Finally, our genomic data confirms the existence of a lineage of C. cerastes in Arabia. All these results highlight the importance of genome-wide data over few genetic markers to study the evolutionary history of species.

Evaluating hybrid speciation and swamping in wild carnivores with a decision-tree approach

Hybridization is an important evolutionary force with a principal role in the origin of new species, known as hybrid speciation. However, ongoing hybridization can create hybrid swamping, in which parental genomes are completely lost. This can become a biodiversity threat if it involves species that have adapted to certain environmental conditions and occur nowhere else. Because conservation scientists commonly have a negative attitude toward hybrids, it is important to improve understanding of the influence of interspecific gene flow on the persistence of species. We reviewed the literature on species hybridization to build a list of all known cases in the order Carnivora. To examine the relative impact, we also noted level of introgression, whether fertile offspring were produced, and whether there was mention of negative or positive evolutionary effects (hybrid speciation and swamping). To evaluate the conservation implications of hybrids, we developed a decision-making tree with which to determine which actions should be taken to manage hybrid species. We found 53 hybrids involving 68 unique taxa, which is roughly 23% of all carnivore species. They mainly involved monophyletic (83%) and sympatric species (75%). For 2 species, the outcome of the assessment was to eliminate or restrict the hybrids: Ethiopian wolf (Canis simensis) and Scottish wildcat (Felis silvestris silvestris). Both species hybridize with their domestic conspecifics. For all other cases, we suggest hybrids be protected in the same manner as native species. We found no evidence of genomic extinction in Carnivora. To the contrary, some species appear to be of hybrid origin, such as the Asiatic black bear (Ursus thibetanus) and African golden wolf (Canis lupaster). Other positive outcomes of hybridization are novel genetic diversity, adaptation to extreme environments, and increased reproductive fitness. These outcomes are particularly valuable for counterbalancing genetic drift and enabling adaptive introgression in a human-dominated world.

White and other fur colourations and hybridization in golden jackals (Canis aureus) in the Carpathian basin

The golden jackal (Canis aureus) is a reoccurring species in the centre of the Carpathian basin, in Hungary. In total, 31 golden jackal tissue samples were collected, from 8 white-coated, 2 black-coated and one mottled animal across Hungary. Sequences and fragment length polymorphisms were studied for white colour (MC1R), and for black coat colouration (CBD103). In each white animal, the most widespread mutation causing white fur colour in dogs in homozygous form was detected. Three animals were found to carry the mutation in heterozygous form. The two black golden jackals were heterozygous for the 3 bp deletion in CBD103 that mutation for black coat colouration in dogs, and one of them also carried the mutation causing white fur. None of the white animals showed signs of hybridization, but both the black and the mottled coloured individuals were found to be hybrids based on genetic testing. Kinship was found three times, twice between white animals, and once between a white animal and an agouti animal carrying the mutation of white coat. Our results confirm the findings that golden jackal-dog hybrids may occur without human intervention, and the detected mutation causing white fur colour in golden jackals could possibly be due to an early hybridization event.

Genomic insights into the conservation of wild and domestic animal diversity: A review

Due to environmental change and anthropogenic activities, global biodiversity has suffered an unprecedented loss, and the world is now heading toward the sixth mass extinction event. This urges the need to step up our efforts to promote the sustainable use of animal genetic resources and plan effective strategies for their conservation. Although habitat preservation and restoration are the primary means of conserving biodiversity, genomic technologies offer a variety of novel tools for identifying biodiversity hotspots and thus, support conservation efforts. Conservation genomics is a broad area of science that encompasses the application of genomic data from thousands or tens of thousands of genome-wide markers to address important conservation biology concerns. Genomic approaches have revolutionized the way we understand and manage animal populations, providing tools to identify and preserve unique genetic variants and alleles responsible for adaptive genetic variation, reducing the deleterious consequences of inbreeding, and increasing the adaptive potential of threatened species. The advancement of genomic technologies, particularly comparative genomic approaches, and the increased accessibility of genomic resources in the form of genome-enabled taxa for non-model organisms, provides a distinct advantage in defining conservation units over traditional genetics approaches. The objective of this review is to provide an exhaustive overview of the concept of conservation genomics, discuss the rationale behind the transition from conservation genetics to genomic approaches, and emphasize the potential applications of genomic techniques for conservation purposes. We also highlight interesting case studies in both livestock and wildlife species where genomic techniques have been used to accomplish conservation goals. Finally, we address some challenges and future perspectives in this field.

Anthropogenic hybridization and its influence on the adaptive potential of the Sardinian wild boar (Sus scrofa meridionalis)

The wild boar (Sus scrofa meridionalis) arrived in Sardinia with the first human settlers in the early Neolithic with the potential to hybridize with the domestic pig (S. s. domesticus) throughout its evolution on the island. In this paper, we investigated the possible microevolutionary effects of such introgressive hybridization on the present wild boar population, comparing Sardinian wild specimens with several commercial pig breeds and Sardinian local pigs, along with a putatively unadmixed wild boar population from Central Italy, all genotyped with a medium density SNP chip. We first aimed at identifying hybrids in the population using different approaches, then examined genomic regions enriched for domestic alleles in the hybrid group, and finally we applied two methods to find regions under positive selection to possibly highlight instances of domestic adaptive introgression into a wild population. We found three hybrids within the Sardinian sample (3.1% out of the whole dataset). We reported 11 significant windows under positive selection with a method that looks for overly differentiated loci in the target population, compared with other two populations. We also identified 82 genomic regions with signs of selection in the domestic pig but not in the wild boar, two of which overlapped with genomic regions enriched for domestic alleles in the hybrid pool. Genes in these regions can be linked with reproductive success. Given our results, domestic introgression does not seem to be pervasive in the Sardinian wild boar. Nevertheless, we suggest monitoring the possible spread of advantageous domestic alleles in the coming years.

Evolutionary history of the extinct wolf population from France in the context of global phylogeographic changes throughout the Holocene

Phylogeographic patterns in large mammals result from natural environmental factors and anthropogenic effects, which in some cases include domestication. The grey wolf was once widely distributed across the Holarctic, but experienced phylogeographic shifts and demographic declines during the Holocene. In the 19th-20th centuries, the species became extirpated from large parts of Europe due to direct extermination and habitat loss. We reconstructed the evolutionary history of the extinct Western European wolves based on the mitogenomic composition of 78 samples from France (Neolithic-20th century) in the context of other populations of wolves and dogs worldwide. We found a close genetic similarity of French wolves from ancient, medieval and recent populations, which suggests the long-term continuity of maternal lineages. MtDNA haplotypes of the French wolves showed large diversity and fell into two main haplogroups of modern Holarctic wolves. Our worldwide phylogeographic analysis indicated that haplogroup W1, which includes wolves from Eurasia and North America, originated in Northern Siberia. Haplogroup W2, which includes only European wolves, originated in Europe ~35 kya and its frequency was reduced during the Holocene due to an expansion of haplogroup W1 from the east. Moreover, we found that dog haplogroup D, currently restricted to Europe and the Middle East, was nested within the wolf haplogroup W2. This suggests European origin of haplogroup D, probably as a result of an ancient introgression from European wolves. Our results highlight the dynamic evolutionary history of European wolves during the Holocene, with a partial lineage replacement and introgressive hybridization with local dog populations.

Analysis of the genetic loci of pigment pattern evolution in vertebrates

Vertebrate pigmentation patterns are amongst the best characterised model systems for studying the genetic basis of adaptive evolution. The wealth of available data on the genetic basis for pigmentation evolution allows for analysis of trends and quantitative testing of evolutionary hypotheses. We employed Gephebase, a database of genetic variants associated with natural and domesticated trait variation, to examine trends in how cis-regulatory and coding mutations contribute to vertebrate pigmentation phenotypes, as well as factors that favour one mutation type over the other. We found that studies with lower ascertainment bias identified higher proportions of cis-regulatory mutations, and that cis-regulatory mutations were more common amongst animals harbouring a higher number of pigment cell classes. We classified pigmentation traits firstly according to their physiological basis and secondly according to whether they affect colour or pattern, and identified that carotenoid-based pigmentation and variation in pattern boundaries are preferentially associated with cis-regulatory change. We also classified genes according to their developmental, cellular, and molecular functions. We found a greater proportion of cis-regulatory mutations in genes implicated in upstream developmental processes compared to those involved in downstream cellular functions, and that ligands were associated with a higher proportion of cis-regulatory mutations than their respective receptors. Based on these trends, we discuss future directions for research in vertebrate pigmentation evolution.

A unique single nucleotide polymorphism in Agouti Signalling Protein (ASIP) gene changes coat colour of Sri Lankan leopard (Panthera pardus kotiya) to dark black

The Sri Lankan leopard (Panthera pardus kotiya) is an endangered subspecies restricted to isolated and fragmented populations in Sri Lanka. Among them, melanistic leopards have been recorded on a few occasions. Literature suggests the evolution of melanism several times in the Felidae family, with three species having distinct mutations. Nevertheless, the mutations or other variations in the remaining species, including Sri Lankan melanistic leopard, are unknown. We used reference-based assembled nuclear genomes of Sri Lankan wild type and melanistic leopards and de novo assembled mitogenomes of the same to investigate the genetic basis, adaptive significance, and evolutionary history of the Sri Lankan melanistic leopard. Interestingly, we identified a single nucleotide polymorphism in exon-4 Sri Lankan melanistic leopard, which may completely ablate Agouti Signalling Protein (ASIP) function. The wild type leopards in Sri Lanka did not carry this mutation, suggesting the cause for the occurrence of melanistic leopords in the population. Comparative analysis of existing genomic data in the literature suggests it as a P. p. kotiya specific mutation and a novel mutation in the ASIP-gene of the Felidae family, contributing to naturally occurring colour polymorphism. Our data suggested the coalescence time of Sri Lankan leopards at ~0.5 million years, sisters to the Panthera pardus lineage. The genetic diversity was low in Sri Lankan leopards. Further, the P. p. kotiya melanistic leopard is a different morphotype of the P. p. kotiya wildtype leopard resulting from the mutation in the ASIP-gene. The ability of black leopards to camouflage, along with the likelihood of recurrence and transfer to future generations, suggests that this rare mutation could be environment-adaptable.

Balancing selection on an MYB transcription factor maintains the twig trichome color variation in Melastoma normale

BACKGROUND

The factors that maintain phenotypic and genetic variation within a population have received long-term attention in evolutionary biology. Here the genetic basis and evolution of the geographically widespread variation in twig trichome color (from red to white) in a shrub Melastoma normale was investigated using Pool-seq and evolutionary analyses.

RESULTS

The results show that the twig trichome coloration is under selection in different light environments and that a 6-kb region containing an R2R3 MYB transcription factor gene is the major region of divergence between the extreme red and white morphs. This gene has two highly divergent groups of alleles, one of which likely originated from introgression from another species in this genus and has risen to high frequency (> 0.6) within each of the three populations under investigation. In contrast, polymorphisms in other regions of the genome show no sign of differentiation between the two morphs, suggesting that genomic patterns of diversity have been shaped by homogenizing gene flow. Population genetics analysis reveals signals of balancing selection acting on this gene, and it is suggested that spatially varying selection is the most likely mechanism of balancing selection in this case.

CONCLUSIONS

This study demonstrate that polymorphisms on a single transcription factor gene largely confer the twig trichome color variation in M. normale, while also explaining how adaptive divergence can occur and be maintained in the face of gene flow.

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.

Parasitic infection increases risk-taking in a social, intermediate host carnivore

Toxoplasma gondii is a protozoan parasite capable of infecting any warm-blooded species and can increase risk-taking in intermediate hosts. Despite extensive laboratory research on the effects of T. gondii infection on behaviour, little is understood about the effects of toxoplasmosis on wild intermediate host behavior. Yellowstone National Park, Wyoming, USA, has a diverse carnivore community including gray wolves (Canis lupus) and cougars (Puma concolor), intermediate and definitive hosts of T. gondii, respectively. Here, we used 26 years of wolf behavioural, spatial, and serological data to show that wolf territory overlap with areas of high cougar density was an important predictor of infection. In addition, seropositive wolves were more likely to make high-risk decisions such as dispersing and becoming a pack leader, both factors critical to individual fitness and wolf vital rates. Due to the social hierarchy within a wolf pack, we hypothesize that the behavioural effects of toxoplasmosis may create a feedback loop that increases spatial overlap and disease transmission between wolves and cougars. These findings demonstrate that parasites have important implications for intermediate hosts, beyond acute infections, through behavioural impacts. Particularly in a social species, these impacts can surge beyond individuals to affect groups, populations, and even ecosystem processes.

Disease outbreaks select for mate choice and coat color in wolves

We know much about pathogen evolution and the emergence of new disease strains, but less about host resistance and how it is signaled to other individuals and subsequently maintained. The cline in frequency of black-coated wolves (Canis lupus) across North America is hypothesized to result from a relationship with canine distemper virus (CDV) outbreaks. We tested this hypothesis using cross-sectional data from wolf populations across North America that vary in the prevalence of CDV and the allele that makes coats black, longitudinal data from Yellowstone National Park, and modeling. We found that the frequency of CDV outbreaks generates fluctuating selection that results in heterozygote advantage that in turn affects the frequency of the black allele, optimal mating behavior, and black wolf cline across the continent.

Coyotes in New York City Carry Variable Genomic Dog Ancestry and Influence Their Interactions with Humans

Coyotes are ubiquitous on the North American landscape as a result of their recent expansion across the continent. They have been documented in the heart of some of the most urbanized cities, such as Chicago, Los Angeles, and New York City. Here, we explored the genomic composition of 16 coyotes in the New York metropolitan area to investigate genomic demography and admixture for urban-dwelling canids in Queens County, New York. We identified moderate-to-high estimates of relatedness among coyotes living in Queens (r = 0.0–0.5) and adjacent neighborhoods, suggestive of a relatively small population. Although we found low background levels of domestic-dog ancestry across most coyotes in our sample (5%), we identified a male suspected to be a first-generation coyote–dog hybrid with 46% dog ancestry, as well as his two putative backcrossed offspring that carried approximately 25% dog ancestry. The male coyote–dog hybrid and one backcrossed offspring each carried two transposable element insertions that are associated with human-directed hypersociability in dogs and gray wolves. An additional, unrelated coyote with little dog ancestry also carried two of these insertions. These genetic patterns suggest that gene flow from domestic dogs may become an increasingly important consideration as coyotes continue to inhabit metropolitan regions.

Counteracting forces of introgressive hybridization and interspecific competition shape the morphological traits of cryptic Iberian Eptesicus bats

Cryptic species that coexist in sympatry are likely to simultaneously experience strong competition and hybridization. The first phenomenon would lead to character displacement, whereas the second can potentially promote morphological similarity through adaptive introgression. The main goal of this work was to investigate the effect of introgressive hybridization on the morphology of cryptic Iberian Eptesicus bats when facing counteracting evolutionary forces from interspecific competition. We found substantial overlap both in dentition and in wing morphology traits, though mainly in individuals in sympatry. The presence of hybrids contributes to a fifth of this overlap, with hybrids showing traits with intermediate morphometry. Thus, introgressive hybridization may contribute to species adaptation to trophic and ecological space responding directly to the macro-habitats characteristics of the sympatric zone and to local prey availability. On the other hand, fur shade tended to be browner and brighter in hybrids than parental species. Colour differences could result from partitioning of resources as an adaptation to environmental factors such as roost and microhabitats. We argue that a balance between adaptive introgression and niche partitioning shapes species interactions with the environment through affecting morphological traits under selection.

Grey wolf genomic history reveals a dual ancestry of dogs

The grey wolf (Canis lupus) was the first species to give rise to a domestic population, and they remained widespread throughout the last Ice Age when many other large mammal species went extinct. Little is known, however, about the history and possible extinction of past wolf populations or when and where the wolf progenitors of the present-day dog lineage (Canis familiaris) lived^1–8. Here we analysed 72 ancient wolf genomes spanning the last 100,000 years from Europe, Siberia and North America. We found that wolf populations were highly connected throughout the Late Pleistocene, with levels of differentiation an order of magnitude lower than they are today. This population connectivity allowed us to detect natural selection across the time series, including rapid fixation of mutations in the gene IFT88 40,000–30,000 years ago. We show that dogs are overall more closely related to ancient wolves from eastern Eurasia than to those from western Eurasia, suggesting a domestication process in the east. However, we also found that dogs in the Near East and Africa derive up to half of their ancestry from a distinct population related to modern southwest Eurasian wolves, reflecting either an independent domestication process or admixture from local wolves. None of the analysed ancient wolf genomes is a direct match for either of these dog ancestries, meaning that the exact progenitor populations remain to be located.

DNA from ancient wolves spanning 100,000 years sheds light on wolves’ evolutionary history and the genomic origin of dogs.

The natural history and ecology of melanism in red wolf and coyote populations of the southeastern United States – evidence for Gloger’s rule

Background

Gloger’s rule postulates that animals should be darker colored in warm and humid regions where dense vegetation and dark environments are common. Although rare in Canis populations, melanism in wolves is more common in North America than other regions globally and is believed to follow Gloger’s rule. In the temperate forests of the southeastern United States, historical records of red wolf (Canis rufus) and coyote (Canis latrans) populations document a consistent presence of melanism. Today, the melanistic phenotype is extinct in red wolves while occurring in coyotes and red wolf-coyote hybrids who occupy the red wolf's historical range. To assess if Gloger’s rule could explain the occurrence and maintenance of melanistic phenotypes in Canis taxa, we investigated differences in morphology, habitat selection, and survival associated with pelage color using body measurements, GPS tracking data, and long-term capture-mark-recapture and radio-telemetry data collected on coyotes and hybrids across the southeastern United States.

Results

We found no correlation between morphometrics and pelage color for Canis taxa. However, we observed that melanistic coyotes and hybrids experienced greater annual survival than did their gray conspecifics. Furthermore, we observed that melanistic coyotes maintained larger home ranges and exhibited greater selection for areas with dense canopy cover and wetlands than did gray coyotes.

Conclusions

In the southeastern United States, pelage color influenced habitat selection by coyotes and annual survival of coyotes and hybrids providing evidence that Gloger’s rule is applicable to canids inhabiting regions with dense canopy cover and wetlands. Greater annual survival rates observed in melanistic Canis may be attributed to better concealment in areas with dense canopy cover such as coastal bottomland forests. We suggest that the larger home range sizes of melanistic coyotes may reflect the trade-off of reduced foraging efficiency in lower quality wetland habitat for improved survival. Larger home ranges and differential use of land cover by melanistic coyotes may facilitate weak assortative mating in eastern coyote populations, in which melanistic animals may have lower success of finding compatible mates in comparison to gray conspecifics. We offer that our observations provide a partial explanation for why melanism is relatively low (< 10%) but consistent within coyote populations throughout southeastern parts of their range.

Melanocortin-1 receptor mutations and pigmentation: Insights from large animals

The melanocortin-1 receptor (MC1R) is a G protein-coupled receptor expressed in cutaneous and hair follicle melanocytes, and plays a central role in coat color determination in vertebrates. Numerous MC1R variants have been identified in diverse species. Some of these variants have been associated with specific hair and skin color phenotypes in humans as well as coat color in animals. Gain-of-function mutations of the MC1R gene cause dominant or partially dominant black/dark coat color, and loss-of-function mutations of the MC1R gene cause recessive or partially recessive red/yellow/pale coat color phenotypes. These have been well documented in a large number of mammals, including human, dog, cattle, horse, sheep, pig, and fox. Higher similarities between large mammals and humans makes them better models to understand pathogenesis of human diseases caused by MC1R mutations. High identities in MC1Rs and similar variants identified in both humans and large mammals also provide an opportunity for receptor structure and function study. In this review, we aim to summarize the naturally occurring mutations of MC1R in humans and large animals.

Evolution of assortative mating following selective introgression of pigmentation genes between two Drosophila species

Adaptive introgression is ubiquitous in animals, but experimental support for its role in driving speciation remains scarce. In the absence of conscious selection, admixed laboratory strains of Drosophila asymmetrically and progressively lose alleles from one parental species and reproductive isolation against the predominant parent ceases after 10 generations. Here, we selectively introgressed during 1 year light pigmentation genes of D. santomea into the genome of its dark sibling D. yakuba, and vice versa. We found that the pace of phenotypic change differed between the species and the sexes and identified through genome sequencing common as well as distinct introgressed loci in each species. Mating assays showed that assortative mating between introgressed flies and both parental species persisted even after 4 years (~60 generations) from the end of the selection. Those results indicate that selective introgression of as low as 0.5% of the genome can beget morphologically distinct and reproductively isolated strains, two prerequisites for the delimitation of new species. Our findings hence represent a significant step toward understanding the genome‐wide dynamics of speciation‐through‐introgression.

Introgressive hybridisation between domestic pigs (Sus scrofa domesticus) and endemic Corsican wild boars (S. s. meridionalis): effects of human-mediated interventions

Owing to the intensified domestication process with artificial trait selection, introgressive hybridisation between domestic and wild species poses a management problem. Traditional free-range livestock husbandry, as practiced in Corsica and Sardinia, is known to facilitate hybridisation between wild boars and domestic pigs (Sus scrofa). Here, we assessed the genetic distinctness and genome-wide domestic pig ancestry levels of the Corsican wild boar subspecies S. s. meridionalis, with reference to its Sardinian conspecifics, employing a genome-wide single nucleotide polymorphism (SNP) assay and mitochondrial control region (mtCR) haplotypes. We also assessed the reliance of morphological criteria and the melanocortin-1 receptor (MC1R) coat colour gene to identify individuals with domestic introgression. While Corsican wild boars showed closest affinity to Sardinian and Italian wild boars compared to other European populations based on principal component analysis, the observation of previously undescribed mtCR haplotypes and high levels of nuclear divergence (Weir’s θ > 0.14) highlighted the genetic distinctness of Corsican S. s. meridionalis. Across three complementary analyses of mixed ancestry (i.e., STRUCTURE, PCADMIX, and ELAI), proportions of domestic pig ancestry were estimated at 9.5% in Corsican wild boars, which was significantly higher than in wild boars in Sardinia, where free-range pig keeping was banned in 2012. Comparison of morphologically pure- and hybrid-looking Corsican wild boars suggested a weak correlation between morphological criteria and genome-wide domestic pig ancestry. The study highlights the usefulness of molecular markers to assess the direct impacts of management practices on gene flow between domestic and wild species.

A reduced SNP panel to trace gene flow across southern European wolf populations and detect hybridization with other Canis taxa

Intra- and inter-specific gene flow are natural evolutionary processes. However, human-induced hybridization is a global conservation concern across taxa, and the development of discriminant genetic markers to differentiate among gene flow processes is essential. Wolves (Canis lupus) are affected by hybridization, particularly in southern Europe, where ongoing recolonization of historic ranges is augmenting gene flow among divergent populations. Our aim was to provide diagnostic canid markers focused on the long-divergent Iberian, Italian and Dinaric wolf populations, based on existing genomic resources. We used 158 canid samples to select a panel of highly informative single nucleotide polymorphisms (SNPs) to (i) distinguish wolves in the three regions from domestic dogs (C. l. familiaris) and golden jackals (C. aureus), and (ii) identify their first two hybrid generations. The resulting 192 SNPs correctly identified the five canid groups, all simulated first-generation (F1) hybrids (0.482 ≤ Q_i ≤ 0.512 between their respective parental groups) and all first backcross (BC1) individuals (0.723 ≤ Q_i ≤ 0.827 to parental groups). An assay design and test with invasive and non-invasive canid samples performed successfully for 178 SNPs. By separating natural population admixture from inter-specific hybridization, our reduced panel can help advance evolutionary research, monitoring, and timely conservation management.

Widespread introgression across a phylogeny of 155 Drosophila genomes

Genome-scale sequence data have invigorated the study of hybridization and introgression, particularly in animals. However, outside of a few notable cases, we lack systematic tests for introgression at a larger phylogenetic scale across entire clades. Here, we leverage 155 genome assemblies from 149 species to generate a fossil-calibrated phylogeny and conduct multilocus tests for introgression across 9 monophyletic radiations within the genus Drosophila. Using complementary phylogenomic approaches, we identify widespread introgression across the evolutionary history of Drosophila. Mapping gene-tree discordance onto the phylogeny revealed that both ancient and recent introgression has occurred across most of the 9 clades that we examined. Our results provide the first evidence of introgression occurring across the evolutionary history of Drosophila and highlight the need to continue to study the evolutionary consequences of hybridization and introgression in this genus and across the tree of life.

Settlement of a stable wolf pack in a highly anthropic area of Pisan hills: Relationship with animal husbandry and hunting in a human-wolf coexistence perspective

Anthropic areas play a pivot role for main wolf conservation challenges. Wolf presence in the higher Pisan hills has been well documented while wolf settlement in the lower Pisan hills is still uncertain. In this study, long-term information on wolf presence in a highly anthropic area of the lower Pisan hills was collected by using non-invasive monitoring techniques. Furthermore, both the relationship of this predator with human activity and the impact of hunting on wolf presence have been investigated. The results obtained indicate the presence of a stable and reproductive wolf pack composed by both Italian wolf and hybrids individuals in the municipalities of Crespina Lorenzana and Casciana Terme Lari. A high impact of wolf on livestock was recorded in this area since no prevention systems were adopted by farmers. Wolf appears not to have a negative impact on wild boar population. Similarly, wild boar drive hunting does not appear to affect the wolf pack presence in the area. Thereby wolf may play a key role as controller of wild population. Prevention strategies improvement becomes instrumental to promote wolf-human coexistence. Further investigation to monitor pack hybridization level and turnover and to assess the impact of packs on wild population and livestock in anthropic areas is desirable.

The myth of wild dogs in Australia: are there any out there?

Hybridisation between wild and domestic canids is a global conservation and management issue. In Australia, dingoes are a distinct lineage of wild-living canid with a controversial domestication status. They are mainland Australia’s apex terrestrial predator. There is ongoing concern that the identity of dingoes has been threatened from breeding with domestic dogs, and that feral dogs have established populations in rural Australia. We collate the results of microsatellite DNA testing from 5039 wild canids to explore patterns of domestic dog ancestry in dingoes and observations of feral domestic dogs across the continent. Only 31 feral dogs were detected, challenging the perception that feral dogs are widespread in Australia. First generation dingo × dog hybrids were similarly rare, with only 27 individuals identified. Spatial patterns of genetic ancestry across Australia identified that dingo populations in northern, western and central Australia were largely free from domestic dog introgression. Our findings challenge the perception that dingoes are virtually extinct in the wild and that feral dogs are common. A shift in terminology from wild dog to dingo would better reflect the identity of these wild canids and allow more nuanced debate about the balance between conservation and management of dingoes in Australia.

New developments in the field of genomic technologies and their relevance to conservation management

Recent technological advances in the field of genomics offer conservation managers and practitioners new tools to explore for conservation applications. Many of these tools are well developed and used by other life science fields, while others are still in development. Considering these technological possibilities, choosing the right tool(s) from the toolbox is crucial and can pose a challenging task. With this in mind, we strive to inspire, inform and illuminate managers and practitioners on how conservation efforts can benefit from the current genomic and biotechnological revolution. With inspirational case studies we show how new technologies can help resolve some of the main conservation challenges, while also informing how implementable the different technologies are. We here focus specifically on small population management, highlight the potential for genetic rescue, and discuss the opportunities in the field of gene editing to help with adaptation to changing environments. In addition, we delineate potential applications of gene drives for controlling invasive species. We illuminate that the genomic toolbox offers added benefit to conservation efforts, but also comes with limitations for the use of these novel emerging techniques.

Identification of Wolf-Dog Hybrids in Europe – An Overview of Genetic Studies

Significant development of genetic tools during the last decades provided opportunities for more detailed analyses and deeper understanding of species hybridization. New genetic markers allowed for reliable identification of admixed individuals deriving from recent hybridization events (a few generations) and those originating from crossings up to 19 generations back. Implementation of microsatellites (STRs) together with Bayesian clustering provided abundant knowledge regarding presence of admixed individuals in numerous populations and helped understand the problematic nature of studying hybridization (i.a., defining a reliable thresholds for recognizing individuals as admixed or obtaining well-grounded results representing actual proportion of hybrids in a population). Nevertheless, their utilization is limited to recent crossbreeding events. Single Nucleotide Polymorphisms (SNPs) proved to be more sensible tools for admixture analyses furnishing more reliable knowledge, especially for older generation backcrosses. Small sets of Ancestry Informative Markers (AIMs) of both types of markers were effective enough to implement in monitoring programs, however, SNPs seem to be more appropriate because of their ability to identify admixed individuals up to 3rd generations. The main aim of this review is to summarize abundant knowledge regarding identification of wolf-dog hybrids in Europe and discuss the most relevant problems relating to the issue, together with advantages and disadvantages of implemented markers and approaches.

The genic view of hybridization in the Anthropocene

Human impact is noticeable around the globe, indicating that a new era might have begun: the Anthropocene. Continuing human activities, including land-use changes, introduction of non-native species and rapid climate change, are altering the distributions of countless species, often giving rise to human-mediated hybridization events. While the interbreeding of different populations or species can have detrimental effects, such as genetic extinction, it can be beneficial in terms of adaptive introgression or an increase in genetic diversity. In this paper, I first review the different mechanisms and outcomes of anthropogenic hybridization based on literature from the last five years (2016-2020). The most common mechanisms leading to the interbreeding of previously isolated taxa include habitat change (51% of the studies) and introduction of non-native species (34% intentional and 19% unintentional). These human-induced hybridization events most often result in introgression (80%). The high incidence of genetic exchange between the hybridizing taxa indicates that the application of a genic view of speciation (and introgression) can provide crucial insights on how to address hybridization events in the Anthropocene. This perspective considers the genome as a dynamic collection of genetic loci with distinct evolutionary histories, giving rise to a heterogenous genomic landscape in terms of genetic differentiation and introgression. First, understanding this genomic landscape can lead to a better selection of diagnostic genetic markers to characterize hybrid populations. Second, describing how introgression patterns vary across the genome can help to predict the likelihood of negative processes, such as demographic and genetic swamping, as well as positive outcomes, such as adaptive introgression. It is especially important to not only quantify how much genetic material introgressed, but also what has been exchanged. Third, comparing introgression patterns in pre-Anthropocene hybridization events with current human-induced cases might provide novel insights into the likelihood of genetic swamping or species collapse during an anthropogenic hybridization event. However, this comparative approach remains to be tested before it can be applied in practice. Finally, the genic view of introgression can be combined with conservation genomic studies to determine the legal status of hybrids and take appropriate measures to manage anthropogenic hybridization events. The interplay between evolutionary and conservation genomics will result in the constant exchange of ideas between these fields which will not only improve our knowledge on the origin of species, but also how to conserve and protect them.

Human-modified canids in human-modified landscapes: The evolutionary consequences of hybridization for grey wolves and free-ranging domestic dogs

Introgressive hybridization between domestic animals and their wild relatives is an indirect form of human-induced evolution, altering gene pools and phenotypic traits of wild and domestic populations. Although this process is well documented in many taxa, its evolutionary consequences are poorly understood. In this study, we assess introgression patterns in admixed populations of Eurasian wolves and free-ranging domestic dogs (FRDs), identifying chromosomal regions with significantly overrepresented hybrid ancestry and assessing whether genes located within these regions show signatures of selection. Although the dog admixture proportion in West Eurasian wolves (2.7%) was greater than the wolf admixture proportion in FRDs (0.75%), the number and average length of chromosomal blocks showing significant overrepresentation of hybrid ancestry were smaller in wolves than FRDs. In wolves, 6% of genes located within these blocks showed signatures of positive selection compared to 23% in FRDs. We found that introgression from wolves may provide a considerable adaptive advantage to FRDs, counterbalancing some of the negative effects of domestication, which can include reduced genetic diversity and excessive tameness. In wolves, introgression from FRDs is mostly driven by drift, with a small number of positively selected genes associated with brain function and behaviour. The predominance of drift may be the consequence of small effective size of wolf populations, which reduces efficiency of selection for weakly advantageous or against weakly disadvantageous introgressed variants. Small wolf population sizes result largely from human-induced habitat loss and hunting, thus linking introgression rates to anthropogenic processes. Our results imply that maintenance of large population sizes should be an important element of wolf management strategies aimed at reducing introgression rates of dog-derived variants.

Evidence of stock connectivity, hybridization, and misidentification in white anglerfish supports the need of a genetics-informed fisheries management framework

Understanding population connectivity within a species as well as potential interactions with its close relatives is crucial to define management units and to derive efficient management actions. However, although genetics can reveal mismatches between biological and management units and other relevant but hidden information such as species misidentification or hybridization, the uptake of genetic methods by the fisheries management process is far from having been consolidated. Here, we have assessed the power of genetics to better understand the population connectivity of white (Lophius piscatorius) and its interaction with its sister species, the black anglerfish (Lophius budegassa). Our analyses, based on thousands of genome-wide single nucleotide polymorphisms, show three findings that are crucial for white anglerfish management. We found (i) that white anglerfish is likely composed of a single panmictic population throughout the Northeast Atlantic, challenging the three-stock based management, (ii) that a fraction of specimens classified as white anglerfish using morphological characteristics are genetically identified as black anglerfish (L. budegassa), and iii) that the two Lophius species naturally hybridize leading to a population of hybrids of up to 20% in certain areas. Our results set the basics for a genetics-informed white anglerfish assessment framework that accounts for stock connectivity, revises and establishes new diagnostic characters for Lophius species identification, and evaluates the effect of hybrids in the current and future assessments of the white anglerfish. Furthermore, our study contributes to provide additional evidence of the potentially negative consequences of ignoring genetic data for assessing fisheries resources.

K Locus Effects in Gray Wolves: Experimental Assessment of TLR3 Signaling and the Gene Expression Response to Canine Distemper Virus

In North American gray wolves, black coat color is dominantly inherited via a 3 base pair coding deletion in the canine beta defensin 3 (CBD103) gene. This 3 base pair deletion, called the KB allele, was introduced through hybridization with dogs and subsequently underwent a selective sweep that increased its frequency in wild wolves. Despite apparent positive selection, KBB wolves have lower fitness than wolves with the KyB genotype, even though the 2 genotypes show no observable differences in black coat color. Thus, the KB allele is thought to have pleiotropic effects on as-yet unknown phenotypes. Given the role of skin-expressed CBD103 in innate immunity, we hypothesized that the KB allele influences the keratinocyte gene expression response to TLR3 pathway stimulation and/or infection by canine distemper virus (CDV). To test this hypothesis, we developed a panel of primary epidermal keratinocyte cell cultures from 24 wild North American gray wolves of both Kyy and KyB genotypes. In addition, we generated an immortalized Kyy line and used CRISPR/Cas9 editing to produce a KyB line on the same genetic background. We assessed the transcriptome-wide responses of wolf keratinocytes to the TLR3 agonist polyinosinic:polycytidylic acid (polyI:C), and to live CDV. K locus genotype did not predict the transcriptional response to either challenge, suggesting that variation in the gene expression response does not explain pleiotropic effects of the KB allele on fitness. This study supports the feasibility of using cell culture methods to investigate the phenotypic effects of naturally occurring genetic variation in wild mammals.

Introgression of ASIP and TYRP1 Alleles Explains Coat Color Variation in Valais Goats

The Valais Blackneck goat is a Swiss goat breed with a characteristic coat color phenotype. Before the revision of the breed standard in 1938, 4 different color varieties of Valais goats were known. Besides Blackneck animals resembling the modern breed standard, the brown and white Copperneck goat, the white Capra Sempione, and the greyish Grüenochte comprised the historic Valais goats. The brown pigmentation of Copperneck goats had previously been traced back to an introgression of a mutant TYRP1 allele from Toggenburg goats. In the present study, we identified additional introgression events of distinct ASIP alleles causing the remaining 2 rare coat color patterns within the Valais Blackneck goat breed. We identified the introgression of the AWt allele from Appenzell or Saanen goats in white Capra Sempione goats. Similarly, introgression of the Apc allele from Peacock goats resulted in the greyish Grüenochte phenotype. These results demonstrate past hybridization events between breeds that are separated today. A perfect genotype-phenotype association in 393 Valais goats supported the causality of the genotyped variants for the different coat color phenotypes. Our study gives insights into the introgression of functionally relevant copy number variant (CNV) alleles controlling pigmentation between goat breeds with strikingly different coat color patterns.

The integrative biology of genetic dominance

Dominance is a basic property of inheritance systems describing the link between a diploid genotype at a single locus and the resulting phenotype. Models for the evolution of dominance have long been framed as an opposition between the irreconcilable views of Fisher in 1928 supporting the role of largely elusive dominance modifiers and Wright in 1929, who viewed dominance as an emerging property of the structure of enzymatic pathways. Recent theoretical and empirical advances however suggest that these opposing views can be reconciled, notably using models investigating the regulation of gene expression and developmental processes. In this more comprehensive framework, phenotypic dominance emerges from departures from linearity between any levels of integration in the genotype‐to‐phenotype map. Here, we review how these different models illuminate the emergence and evolution of dominance. We then detail recent empirical studies shedding new light on the diversity of molecular and physiological mechanisms underlying dominance and its evolution. By reconciling population genetics and functional biology, we hope our review will facilitate cross‐talk among research fields in the integrative study of dominance evolution.

Interface of Human/Wildlife Interactions: An Example of a Bold Coyote (Canis latrans) in Atlanta, GA, USA

There is arguably no other North American species that better illustrates the complexities of the human-wildlife interface than the coyote. In this study, a melanistic coyote in metropolitan Atlanta, Georgia was exhibiting unusually bold behaviors that included encounters with humans, domestic dogs, and attempts to enter homes. After tracking this coyote (nicknamed Carmine) across a highly urbanized landscape with participatory science, including at least 80 publicly reported sightings, he was captured and relocated to a wildlife sanctuary. Genome-wide analyses revealed 92.8% coyote ancestry, 1.7% gray wolf ancestry, and 5.5% domestic dog ancestry. The dog alleles in Carmine’s genome were estimated to have been acquired by his ancestors 14–29 years ago. Despite his bold behavior, Carmine did not carry any mutations known to shape hypersociability in canines. He did, however, carry a single copy of the dominant mutation responsible for his melanistic coat color. This detailed study of Carmine dispels common assumptions about the reticent coyote personality and the origins of behavior. His unusual bold behavior created a higher level of human-coyote interaction. He now serves as a public ambassador for human-wildlife coexistence, urging the global community to reconsider mythologies about wildlife and promote coexistence with them in landscapes significantly altered by human activity in our rapidly changing world.

Social environment and genetics underlie body site-specific microbiomes of Yellowstone National Park gray wolves (Canis lupus)

The host-associated microbiome is an important player in the ecology and evolution of species. Despite growing interest in the medical, veterinary, and conservation communities, there remain numerous questions about the primary factors underlying microbiota, particularly in wildlife. We bridged this knowledge gap by leveraging microbial, genetic, and observational data collected in a wild, pedigreed population of gray wolves (Canis lupus) inhabiting Yellowstone National Park. We characterized body site-specific microbes across six haired and mucosal body sites (and two fecal samples) using 16S rRNA amplicon sequencing. At the phylum level, we found that the microbiome of gray wolves primarily consists of Actinobacteria, Bacteroidetes, Firmicutes, Fusobacteria, and Proteobacteria, consistent with previous studies within Mammalia and Canidae. At the genus level, we documented body site-specific microbiota with functions relevant to microenvironment and local physiological processes. We additionally employed observational and RAD sequencing data to examine genetic, demographic, and environmental correlates of skin and gut microbiota. We surveyed individuals across several levels of pedigree relationships, generations, and social groups, and found that social environment (i.e., pack) and genetic relatedness were two primary factors associated with microbial community composition to differing degrees between body sites. We additionally reported body condition and coat color as secondary factors underlying gut and skin microbiomes, respectively. We concluded that gray wolf microbiota resemble similar host species, differ between body sites, and are shaped by numerous endogenous and exogenous factors. These results provide baseline information for this long-term study population and yield important insights into the evolutionary history, ecology, and conservation of wild wolves and their associated microbes.

Southern introgression increases adaptive immune gene variability in northern range margin populations of Fire-bellied toad

Northern range margin populations of the European fire-bellied toad (Bombina bombina) have rapidly declined during recent decades. Extensive agricultural land use has fragmented the landscape, leading to habitat disruption and loss, as well as eutrophication of ponds. In Northern Germany (Schleswig-Holstein) and Southern Sweden (Skåne), this population decline resulted in decreased gene flow from surrounding populations, low genetic diversity, and a putative reduction in adaptive potential, leaving populations vulnerable to future environmental and climatic changes. Previous studies using mitochondrial control region and nuclear transcriptome-wide SNP data detected introgressive hybridization in multiple northern B. bombina populations after unreported release of toads from Austria. Here, we determine the impact of this introgression by comparing the body conditions (proxy for fitness) of introgressed and nonintrogressed populations and the genetic consequences in two candidate genes for putative local adaptation (the MHC II gene as part of the adaptive immune system and the stress response gene HSP70 kDa). We detected regional differences in body condition and observed significantly elevated levels of within individual MHC allele counts in introgressed Swedish populations, associated with a tendency toward higher body weight, relative to regional nonintrogressed populations. These differences were not observed among introgressed and nonintrogressed German populations. Genetic diversity in both MHC and HSP was generally lower in northern than Austrian populations. Our study sheds light on the potential benefits of translocations of more distantly related conspecifics as a means to increase adaptive genetic variability and fitness of genetically depauperate range margin populations without distortion of local adaptation.

A sliver of the past: The decimation of the genetic diversity of the Mexican wolf

The endangered Mexican wolf (Canis lupus baileyi) is known to carry exceedingly low levels of genetic diversity. This could be (i) the result of long-term evolutionary patterns as they exist at the southernmost limit of the species distribution at a relatively reduced effective size, or (ii) due to rapid population decline caused by human persecution over the last century. If the former, purifying selection is expected to have minimized the impact of inbreeding. If the latter, rapid and recent declines in genetic diversity may have resulted in severe fitness consequences. To differentiate these hypotheses, we conducted comparative whole-genome analyses of five historical Mexican wolves (1907-1917) and 18 contemporary Mexican and grey wolves from North America and Eurasia. Based on whole-genome data, historical and modern Mexican wolves together form a discrete unit. Moreover, we found that modern Mexican wolves have reduced genetic diversity and increased inbreeding relative to the historical population, which was widespread across the southwestern United States and not restricted to Mexico as previously assumed. Finally, although Mexican wolves have evolved in sympatry with coyotes (C. latrans), we observed lower introgression between historical Mexican wolves and coyotes than with modern Mexican wolves, despite similarities in body size. Taken together, our data show that recent population declines probably caused the reduced level of genetic diversity, but not the observed differentiation of the Mexican wolves from other North American wolves.

Exchanging fluids The sociocultural implications of microbial, cultural, and ethnic admixture in Latin America

Knowledge of evolutionary influences on patterns of human mating, social interactions, and differential health is increasing, yet these insights have rarely been applied to historical analyses of human population dynamics. The genetic and evolutionary forces behind biases in interethnic mating and in the health of individuals of different ethnic groups in Latin America and the Caribbean since the European colonization of America are still largely ignored. We discuss how historical and contemporary sociocultural interactions and practices are strongly influenced by population-level evolutionary forces. Specifically, we discuss the historical implications of functional (de facto) polygyny, sex-biased admixture, and assortative mating in Latin America. We propose that these three evolutionary mechanisms influenced mating patterns, shaping the genetic and cultural landscape across Latin America and the Caribbean. Further, we discuss how genetic differences between the original populations that migrated at different times into Latin America contributed to their accommodation to and survival in the different local ecologies and interethnic interactions. Relevant medical and social implications follow from the genetic and cultural changes reviewed.

Updating the Bibliography of Interbreeding among Canis in North America

This bibliography provides a collection of references that documents the evolution of studies evidencing interbreeding among Canis species in North America. Over the past several decades, advances in biology and genomic technology greatly improved our ability to detect and characterize species interbreeding, which has significance for understanding species in a changing landscape as well as for endangered species management. This bibliography includes a discussion within each category of interbreeding, the timeline of developing evidence, and includes a review of past research conducted on experimental crosses. Research conducted in the early 20th century is rich with detailed records and photographs of hybrid offspring development and behavior. With the progression of molecular methods, studies can estimate historical demographic parameters and detect chromosomal patterns of ancestry. As these methods continue to increase in accessibility, the field will gain a deeper and richer understanding of the evolutionary history of North American Canis.

Genomic evidence for the Chinese mountain cat as a wildcat conspecific (Felis silvestris bieti) and its introgression to domestic cats

The Qinghai-Tibet Plateau endemic Chinese mountain cat has a controversial taxonomic status, whether it is a true species or a wildcat (Felis silvestris) subspecies and whether it has contributed to cat (F. s. catus) domestication in East Asia. Here, we sampled F. silvestris lineages across China and sequenced 51 nuclear genomes, 55 mitogenomes, and multilocus regions from 270 modern or museum specimens. Genome-wide analyses classified the Chinese mountain cat as a wildcat conspecific F. s. bieti, which was not involved in cat domestication of China, thus supporting a single domestication origin arising from the African wildcat (F. s. lybica). A complex hybridization scenario including ancient introgression from the Asiatic wildcat (F. s. ornata) to F. s. bieti, and contemporary gene flow between F. s. bieti and sympatric domestic cats that are likely recent Plateau arrivals, raises the prospect of disrupted wildcat genetic integrity, an issue with profound conservation implications.

Adding Nuance to Our Understanding of Dog-Wildlife Interactions and the Need for Management

The interactions of dogs and wildlife are receiving increasing attention across the globe. Evidence suggests that dogs can negatively affect wildlife in a variety of ways, including through the risk of predation, by hybridizing with other Canis species, by acting as a reservoir or vector of pathogens, and by competing with wildlife for resources. A multitude of observations and case studies for each of these interactions has led to calls to prioritize increased management of dogs, for instance, through population reduction, vaccination, movement restrictions, and enhanced care of the dogs themselves. Here, I argue that while the risks that dogs present to wildlife are real, they vary in their importance across the globe. Furthermore, often the approaches used to address these risks are championed without a full understanding of the likelihood of success given the necessary spatial scale of management, the availability of alternative management approaches, and the role dogs play in societies. For instance, culling, vaccination, and animal husbandry approaches in reducing the impacts of dogs on wildlife sometimes fail to recognize that local human populations actively recruit replacement dogs, that vaccination often fails to reach levels necessary for herd immunity, and that enhanced dog husbandry may have indirect impacts on wildlife by requiring environmentally impactful activities. I suggest there is a need for attention not only to identify the impacts of dogs but also to determine where and when such interactions with wildlife are problematic and the likelihood of success for any proposed management approach. The impacts of dogs should be mediated in a context-specific manner that accounts for factors such as the local density of dogs, the susceptibility of local wildlife populations to the risks that dog populations may represent, and the local societal norms that underpin how dogs might be managed.