Andersone et al. (2002): Hybridisation between wolves and dogs in Latvia as documented using mitochondrial and microsatellite DNA markers. DOI: 10.1078/1616-5047-00012.
Abstract
Bensch et al. (2006): Selection for Heterozygosity Gives Hope to a Wild Population of Inbred Wolves. DOI: 10.1371/journal.pone.0000072.Crossbreeding between wolves and dogs in the wild has been sometimes reported, but always poorly documented in scientific literature. However, documenting frequency of hybridisation and introgression is important for conservation of wild living wolf populations and for the management of free ranging dogs. Here we report the results of molecular genetic analyses of 31 wolf samples collected in Latvia from 1997 to 1999, including six pups originated from a litter found in northern Latvia in March 1999, and six wolves showing morphological traits that suggested hybrid origin. Nucleotide sequencing of the hypervariable part of the mtDNA control-region and genotyping of 16 microsatellite loci suggested that both pups and the morphologically anomalous wolves might originate from crossbreeding with dogs. Causes of wolf-dog crossbreeding, as well as possible management effort to avoid further hybridisation in the wild, are discussed.
Abstract
Czarnomska et al. (2013): Concordant mitochondrial and microsatellite DNA structuring between Polish lowland and Carpathian Mountain wolves. DOI: 10.1007/s10592-013-0446-2.Recent analyses have questioned the usefulness of heterozygosity estimates as measures of the inbreeding coefficient (f), a finding that may have dramatic consequences for the management of endangered populations. We confirm that f and heterozygosity is poorly correlated in a wild and highly inbred wolf population. Yet, our data show that for each level of f, it was the most heterozygous wolves that established themselves as breeders, a selection process that seems to have decelerated the loss of heterozygosity in the population despite a steady increase of f. The markers contributing to the positive relationship between heterozygosity and breeding success were found to be located on different chromosomes, but there was a substantial amount of linkage disequilibrium in the population, indicating that the markers are reflecting heterozygosity over relatively wide genomic regions. Following our results we recommend that management programs of endangered populations include estimates of both f and heterozygosity, as they may contribute with complementary information about population viability.
Abstract
Donfrancesco et al. (2019): Unravelling the Scientific Debate on How to Address Wolf-Dog Hybridization in Europe. DOI: 10.3389/fevo.2019.00175.Phylogeographic studies of highly mobile large carnivores suggest that intra-specific genetic differentiation of modern species might be the consequence of the most recent Pleistocene glaciation. However, the relative influence of biogeographical processes and subsequent human-induced population fragmentation requires a better understanding. Poland represents the western edge of relatively continuous distributions of many wide-ranging species, e.g. lynx (Lynx lynx), wolves (Canis lupus), moose (Alces alces) and, therefore, a key area for understanding historic and contemporary patterns of gene flow in central Europe. We examined wolf genetic structure in Poland and in a recently recolonized area in eastern Germany using microsatellite profiles (n = 457) and mitochondrial DNA sequencing (mtDNA, n = 333) from faecal samples. We found significant genetic structure and high levels of differentiation between wolves in the Carpathian Mountains and the Polish lowlands. Our findings are consistent with previously reported mtDNA subdivision between northern lowlands and southern mountains, and add new and concordant findings based on autosomal marker variation. Wolves in western Poland and eastern Germany showed limited differentiation from northeastern Poland. Although the presence of private alleles suggests immigration also from areas not sampled in this study, most individuals seem to be immigrants from northeastern Poland or their descendants. We observed moderate genetic differentiation between certain northeastern lowland regions separated by less than 50 km. Moreover, mtDNA results indicated a southeastern subpopulation near the border with Ukraine. The observed structure might reflect landscape fragmentation and/or ecological differences resulting in natal habitat-biased dispersal.
Abstract
Dufresnes et al. (2019): Two decades of non-invasive genetic monitoring of the grey wolves recolonizing the Alps support very limited dog introgression. DOI: 10.1038/s41598-018-37331-x.Anthropogenic hybridization is widely perceived as a threat to the conservation of biodiversity. Nevertheless, to date, relevant policy and management interventions are unresolved and highly convoluted. While this is due to the inherent complexity of the issue, we hereby hypothesize that a lack of agreement concerning management goals and approaches, within the scientific community, may explain the lack of social awareness on this phenomenon, and the absence of effective pressure on decision-makers. By focusing on wolf x dog hybridization in Europe, we hereby (a) assess the state of the art of issues on wolf x dog hybridization within the scientific community, (b) assess the conceptual bases for different viewpoints, and (c) provide a conceptual framework aiming at reducing the disagreements. We adopted the Delphi technique, involving a three-round iterative survey addressed to a selected sample of experts who published at Web of Science listed journals, in the last 10 years on wolf x dog hybridization and related topics. Consensus was reached that admixed individuals should always be defined according to their genetic profile, and that a reference threshold for admixture (i.e., q-value in assignment tests) should be formally adopted for their identification. To mitigate hybridization, experts agreed on adopting preventive, proactive and, when concerning small and recovering wolf populations, reactive interventions. Overall, experts' consensus waned as the issues addressed became increasingly practical, including the adoption of lethal removal. We suggest three non-mutually exclusive explanations for this trend: (i) value-laden viewpoints increasingly emerge when addressing practical issues, and are particularly diverging between experts with different disciplinary backgrounds (e.g., ecologists, geneticists); (ii) some experts prefer avoiding the risk of potentially giving carte blanche to wolf opponents to (illegally) remove wolves, based on the wolf x dog hybridization issue; (iii) room for subjective interpretation and opinions result from the paucity of data on the effectiveness of different management interventions. These results have management implications and reveal gaps in the knowledge on a wide spectrum of issues related not only to the management of anthropogenic hybridization, but also to the role of ethical values and real-world management concerns in the scientific debate.
Abstract
Iacolina et al. (2010): Y-chromosome microsatellite variation in Italian wolves: A contribution to the study of wolf-dog hybridization patterns. DOI: 10.1016/j.mambio.2010.02.004.Potential hybridization between wolves and dogs has fueled the sensitive conservation and political debate underlying the recovery of the grey wolf throughout Europe. Here we provide the first genetic analysis of wolf-dog admixture in an area entirely recolonized, the northwestern Alps. As part of a long-term monitoring program, we performed genetic screening of thousands of non-invasive samples collected in Switzerland and adjacent territories since the return of the wolf in the mid-1990s. We identified a total of 115 individuals, only 2 of them showing significant signs of admixture stemming from past interbreeding with dogs, followed by backcrossing. This low rate of introgression (<2% accounting for all wolves ever detected over 1998–2017) parallels those from other European populations, especially in Western Europe (<7%). Despite potential hybridization with stray dogs, few founders and strong anthropogenic pressures, the genetic integrity of the Alpine population has remained intact throughout the entire recolonization process. In a context of widespread misinformation, this finding should reduce conflicts among the different actors involved and facilitate wolf conservation. Real-time genetic monitoring will be necessary to identify potential hybrids and support an effective management of this emblematic population.
Abstract
Hindrikson (2016): Grey wolf (Canis lupus) populations in Estonia and Europe: genetic diversity, population structure and -processes, and hybridization between wolves and dogs. Dissertation, http://dspace.ut.ee/handle/10062/54145.One major concern in wolf (Canis lupus) conservation is the risk of genetic contamination due to crossbreeding with domestic dogs. Although genetic monitoring of wolf populations has become widely used, the behavioural mechanisms involved in wolf-dog hybridization and the detrimental effects of genetic introgression are poorly known. In this study we analysed Y-chromosome microsatellite variation in the recovering Italian wolf population and detected strikingly different allele frequencies between wolves and dogs. Four Y haplotypes were found in 74 analysed male wolves, and all of them were present in a focus wolf population in the Apennines. On the other hand, only 1 haplotype was found in the recolonizing wolf population from the Western Alps. The most common haplotype in a sample of domestic dogs, was also found in 5 wolves, 2 of which revealing a signature of recent hybridization. Moreover, another suspect hybrid carried a private haplotype of possible canine origin. These results give support to the idea that female wolves can breed with male stray dogs in the wild. The Y-chromosome variation in Italian wolves contrasts with the previously observed lack of mitochondrial variation. Further investigations are needed to clarify at what extent historical or recent wolf-dog hybridization events may have contributed to the observed haplotype diversity. In conclusion, the two molecular markers employed in this study represent effective means to trace directional genetic introgression into the wolves male lineage and have the noteworthy advantage of being suitable for analyses on low-quality DNA samples.
Summary
Hindrikson et al. (2012): Bucking the Trend in Wolf-Dog Hybridization: First Evidence from Europe of Hybridization between Female Dogs and Male Wolves. DOI: 10.1371/journal.pone.0046465.Knowledge of wolf population genetics and hybridization between wolves and dogs are of great importance for effective conservation and management of the species at both local and global scales. There are numerous studies published on wolf population genetics in different countries and regions in Europe, however the data on Baltic population, specifically part of the population represented by Estonian and Latvian wolves, were lacking. Studies including all European countries in a comprehencive analysis of large scale spatial-genetic patterns and trends of genetic variation in Europe were also lacking. The goal of this thesis was to provide information on wolf population structure and processes in Europe with a particular emphasis on Estonia and Latvia, including the wolfdog hybridization.
Hybridization between grey wolf and domestic dog was ascertained in Estonia (for the first time) and Latvia using a combined analysis of maternal, paternal and biparental genetic markers. Six hybrid individuals from Estonia and two from Latvia were initially detected from their atypical morphological traits and their hybrid status was subsequently confirmed using genetic analysis. Analysis of mtDNA showed that the two hybrids from Latvia represented a very rare case of hybridization – the first record from Europe – between a female dog and a male wolf.
Population genetic analysis demonstrated that the relatively small wolf population shared between Estonia and Latvia is represented by four genetic groups. While three of the four genetic groups were geographically well defined, being either Estonian or Latvian based, one of the groups was distributed widely in Estonia and Latvia. The spatially explicit DResD analysis provided clear evidence of spatial variation of genetic divergence: (a) at the smallest spatial scale (20–80 km) several blending areas of different groups appeared with relatively high genetic distance between otherwise geographically closely positioned individuals; (b): at the medium scale (80–140 km) a putative territory of an expanding pack was detected in south-west Estonia, coinciding with one of the core areas of group D (c): at the largest spatial scale (140–250 km) a large area in the northeastern part of Estonia was identified as a migration corridor.
To describe large-scale trends and patterns of genetic variation in European wolf populations, we conducted a meta-analysis based on the results of previous microsatellite studies and included also new data, covering all 19 European countries for which wolf genetic information is available: Norway, Sweden, Finland, Estonia, Latvia, Lithuania, Poland, Czech Republic, Slovakia, Germany, Belarus, Russia, Italy, Croatia, Bulgaria, Bosnia and Herzegovina, Greece, Spain and Portugal. We compared different indices of genetic diversity in wolf populations and found a significant spatial trend in heterozygosity across Europe from south-west (lowest genetic diversity) to north-east (highest). The range of spatial autocorrelation calculated on the basis of three characteristics of genetic28 diversity was 650−850 km, suggesting that the genetic diversity of a given wolf population can be influenced by populations up to 850 km away.
Various human-related factors are undoubtedly the main source of threats to wolf populations in Europe: the majority of populations face similar common threats such as overharvesting (including poaching), low public acceptance, conflicts due to livestock depredation, habitat destruction, barriers to gene flow and interactions with dogs leading to possible hybridization. For the long-term survival and favourable conservation status of European wolves there is a need to increase the overall population size and favour wolf dispersal and connectivity among and within populations. For science-based wolf conservation and management at regional and Europe-wide scales it was suggested (1) to manage wolf populations according to biological units, which requires additional genetic analysis covering all wolf populations in Europe to define the exact number and spatial distribution of populations; (2) to increase scientific knowledge and inform stakeholders and the general public, there is a need to establish a European Union Wolf Scientific Committee and a European Union Reference Laboratory of Wolf Studies.
Abstract
Hindrikson et al. (2017): Wolf population genetics in Europe: a systematic review, meta-analysis and suggestions for conservation and management: Wolf population genetics in Europe. DOI: 10.1111/brv.12298.Studies on hybridization have proved critical for understanding key evolutionary processes such as speciation and adaptation. However, from the perspective of conservation, hybridization poses a concern, as it can threaten the integrity and fitness of many wild species, including canids. As a result of habitat fragmentation and extensive hunting pressure, gray wolf (Canis lupus) populations have declined dramatically in Europe and elsewhere during recent centuries. Small and fragmented populations have persisted, but often only in the presence of large numbers of dogs, which increase the potential for hybridization and introgression to deleteriously affect wolf populations. Here, we demonstrate hybridization between wolf and dog populations in Estonia and Latvia, and the role of both genders in the hybridization process, using combined analysis of maternal, paternal and biparental genetic markers. Eight animals exhibiting unusual external characteristics for wolves - six from Estonia and two from Latvia - proved to be wolf-dog hybrids. However, one of the hybridization events was extraordinary. Previous field observations and genetic studies have indicated that mating between wolves and dogs is sexually asymmetrical, occurring predominantly between female wolves and male dogs. While this was also the case among the Estonian hybrids, our data revealed the existence of dog mitochondrial genomes in the Latvian hybrids and, together with Y chromosome and autosomal microsatellite data, thus provided the first evidence from Europe of mating between male wolves and female dogs. We discuss patterns of sexual asymmetry in wolf-dog hybridization.
Abstract
Gottelli et al. (1994): Molecular genetics of the most endangered canid: the Ethiopian wolf Canis simensis. DOI: 10.1111/j.1365-294X.1994.tb00070.x.The grey wolf (Canis lupus) is an iconic large carnivore that has increasingly been recognized as an apex predator with intrinsic value and a keystone species. However, wolves have also long represented a primary source of human–carnivore conflict, which has led to long‐term persecution of wolves, resulting in a significant decrease in their numbers, genetic diversity and gene flow between populations. For more effective protection and management of wolf populations in Europe, robust scientific evidence is crucial. This review serves as an analytical summary of the main findings from wolf population genetic studies in Europe, covering major studies from the ‘pre‐genomic era’ and the first insights of the ‘genomics era’. We analyse, summarize and discuss findings derived from analyses of three compartments of the mammalian genome with different inheritance modes: maternal (mitochondrial DNA), paternal (Y chromosome) and biparental [autosomal microsatellites and single nucleotide polymorphisms (SNPs)]. To describe large‐scale trends and patterns of genetic variation in European wolf populations, we conducted a meta‐analysis based on the results of previous microsatellite studies and also included new data, covering all 19 European countries for which wolf genetic information is available: Norway, Sweden, Finland, Estonia, Latvia, Lithuania, Poland, Czech Republic, Slovakia, Germany, Belarus, Russia, Italy, Croatia, Bulgaria, Bosnia and Herzegovina, Greece, Spain and Portugal. We compared different indices of genetic diversity in wolf populations and found a significant spatial trend in heterozygosity across Europe from south‐west (lowest genetic diversity) to north‐east (highest). The range of spatial autocorrelation calculated on the basis of three characteristics of genetic diversity was 650−850 km, suggesting that the genetic diversity of a given wolf population can be influenced by populations up to 850 km away. As an important outcome of this synthesis, we discuss the most pressing issues threatening wolf populations in Europe, highlight important gaps in current knowledge, suggest solutions to overcome these limitations, and provide recommendations for science‐based wolf conservation and management at regional and Europe‐wide scales.
Abstract
Kraus et al. (2015): A single-nucleotide polymorphism-based approach for rapid and cost-effective genetic wolf monitoring in Europe based on noninvasively collected samples. DOI: 10.1111/1755-0998.12307.The world's most endangered canid is the Ethiopian wolf Canis simensis, which is found in six isolated areas of the Ethiopian highlands with a total population of no more than 500 individuals. Ethiopian wolf populations are declining due to habitat loss and extermination by humans. Moreover, in at least one population, Ethiopian wolves are sympatric with domestic dogs, which may hybridize with them, compete for food, and act as disease vectors. Using molecular techniques, we address four questions concerning Ethiopian wolves that have conservation implications. First, we determine the relationships of Ethiopian wolves to other wolf‐like canids by phylogenetic analysis of 2001 base pairs of mitochondrial DNA (mtDNA) sequence. Our results suggest that the Ethiopian wolf is a distinct species more closely related to gray wolves and coyotes than to any African canid. The mtDNA sequence similarity with gray wolves implies that the Ethiopian wolf may hybridize with domestic dogs, a recent derivative of the gray wolf. We examine this possibility through mtDNA restriction fragment analysis and analysis of nine microsatellite loci in populations of Ethiopian wolves. The results imply that hybridization has occurred between female Ethiopian wolves and male domestic dogs in one population. Finally, we assess levels of variability within and between two Ethiopian wolf populations. Although these closely situated populations are not differentiated, the level of variability in both is low, suggesting long‐term effective population sizes of less than a few hundred individuals. We recommend immediate captive breeding of Ethiopian wolves to protect their gene pool from dilution and further loss of genetic variability.
Abstract
Lucchini et al. (2004): Evidence of genetic distinction and long-term population decline in wolves (Canis lupus) in the Italian Apennines. DOI: 10.1046/j.1365-294X.2004.02077.x.Noninvasive genetics based on microsatellite markers has become an indispensable tool for wildlife monitoring and conservation research over the past decades. However, microsatellites have several drawbacks, such as the lack of standardisation between laboratories and high error rates. Here, we propose an alternative single‐nucleotide polymorphism (SNP)‐based marker system for noninvasively collected samples, which promises to solve these problems. Using nanofluidic SNP genotyping technology (Fluidigm), we genotyped 158 wolf samples (tissue, scats, hairs, urine) for 192 SNP loci selected from the Affymetrix v2 Canine SNP Array. We carefully selected an optimised final set of 96 SNPs (and discarded the worse half), based on assay performance and reliability. We found rates of missing data in this SNP set of <10% and genotyping error of ~1%, which improves genotyping accuracy by nearly an order of magnitude when compared to published data for other marker types. Our approach provides a tool for rapid and cost‐effective genotyping of noninvasively collected wildlife samples. The ability to standardise genotype scoring combined with low error rates promises to constitute a major technological advancement and could establish SNPs as a standard marker for future wildlife monitoring.
Abstract
McFarlane & Pemberton (2019): Detecting the True Extent of Introgression during Anthropogenic Hybridization. DOI: 10.1016/j.tree.2018.12.013.Historical information suggests the occurrence of an extensive human‐caused contraction in the distribution range of wolves (Canis lupus) during the last few centuries in Europe. Wolves disappeared from the Alps in the 1920s, and thereafter continued to decline in peninsular Italy until the 1970s, when approximately 100 individuals survived, isolated in the central Apennines. In this study we performed a coalescent analysis of multilocus DNA markers to infer patterns and timing of historical population changes in wolves surviving in the Apennines. This population showed a unique mitochondrial DNA control‐region haplotype, the absence of private alleles and lower heterozygosity at microsatellite loci, as compared to other wolf populations. Multivariate, clustering and Bayesian assignment procedures consistently assigned all the wolf genotypes sampled in Italy to a single group, supporting their genetic distinction. Bottleneck tests showed evidences of population decline in the Italian wolves, but not in other populations. Results of a Bayesian coalescent model indicate that wolves in Italy underwent a 100‐ to 1000‐fold population contraction over the past 2000–10 000 years. The population decline was stronger and longer in peninsular Italy than elsewhere in Europe, suggesting that wolves have apparently been genetically isolated for thousands of generations south of the Alps. Ice caps covering the Alps at the Last Glacial Maximum (c. 18 000 years before present), and the wide expansion of the Po River, which cut the alluvial plains throughout the Holocene, might have provided effective geographical barriers to wolf dispersal. More recently, the admixture of Alpine and Apennine wolf populations could have been prevented by deforestation, which was already widespread in the fifteenth century in northern Italy. This study suggests that, despite the high potential rates of dispersal and gene flow, local wolf populations may not have mixed for long periods of time.
Abstract
Mech et al. (2017): Studies of wolf x coyote hybridization via artificial insemination. DOI: 10.1371/journal.pone.0184342.Anthropogenic hybridization is increasingly common and is likely to result in a breakdown of reproductive isolation between ‘good’ species.
Backcrossed individuals that have only a small proportion of one parental genome are difficult to differentiate from parental individuals by using the most common current technologies.
Bimodal hybrid zones are characterized by introgression and backcrossing. The majority of hybrid individuals in these systems have low levels of introgression. The problems posed by bimodal hybrid zones have been largely overlooked in the literature.
Genome-wide sampling of genetic markers at high densities allow increased precision in the estimate of admixture proportions, which makes it feasible to detect multi-generation backcrosses, and will thus make it easier to differentiate bimodal hybrid zones from hybrid swarms or systems without introgression.
Hybridization among naturally separate taxa is increasing owing to human impact, and can result in taxon loss. Previous classification of anthropogenic hybridization has largely ignored the case of bimodal hybrid zones, in which hybrids commonly mate with parental species, resulting in many backcrossed individuals with a small proportion of introgressed genome. Genetic markers can be used to detect such hybrids, but until recently too few markers have been used to detect the true extent of introgression. Recent studies of wolves and trout have employed thousands of markers to reveal previously undetectable backcrosses. This improved resolution will lead to increased detection of late-generation backcrosses, shed light on the consequences of anthropogenic hybridization, and pose new management issues for conservation scientists.
Abstract
Mech et al. (2014): Production of Hybrids between Western Gray Wolves and Western Coyotes. DOI: 10.1371/journal.pone.0088861.Following the production of western gray wolf (Canis lupus) x western coyote (Canis latrans) hybrids via artificial insemination (AI), the present article documents that the hybrids survived in captivity for at least 4 years and successfully bred with each other. It further reports that backcrossing one of the hybrids to a male gray wolf by AI also resulted in the birth of live pups that have survived for at least 10 months. All male hybrids (F1 and F2) produced sperm by about 10 months of age, and sperm quality of the F1 males fell within the fertile range for domestic dogs, but sperm motility and morphology, in particular, were low in F2 males at 10 months but improved in samples taken at 22 months of age. These studies are relevant to a long-standing controversy about the identity of the red wolf (Canis rufus), the existence of a proposed new species (Canis lycaon) of gray wolf, and to the role of hybridization in mammalian evolution.
Abstract
Mellersh et al. (1997): A Linkage Map of the Canine. DOI: 10.1006/geno.1997.5098.Using artificial insemination we attempted to produce hybrids between captive, male, western, gray wolves (Canis lupus) and female, western coyotes (Canis latrans) to determine whether their gametes would be compatible and the coyotes could produce and nurture offspring. The results contribute new information to an ongoing controversy over whether the eastern wolf (Canis lycaon) is a valid unique species that could be subject to the U. S. Endangered Species Act. Attempts with transcervically deposited wolf semen into nine coyotes over two breeding seasons yielded three coyote pregnancies. One coyote ate her pups, another produced a resorbed fetus and a dead fetus by C-section, and the third produced seven hybrids, six of which survived. These results show that, although it might be unlikely for male western wolves to successfully produce offspring with female western coyotes under natural conditions, western-gray-wolf sperm are compatible with western-coyote ova and that at least one coyote could produce and nurture hybrid offspring. This finding in turn demonstrates that gamete incompatibility would not have prevented western, gray wolves from inseminating western coyotes and thus producing hybrids with coyote mtDNA, a claim that counters the view that the eastern wolf is a separate species. However, some of the difficulties experienced by the other inseminated coyotes tend to temper that finding and suggest that more experimentation is needed, including determining the behavioral and physical compatibility of western gray wolves copulating with western coyotes. Thus although our study adds new information to the controversy, it does not settle it. Further study is needed to determine whether the putative Canis lycaon is indeed a unique species.
Abstract
Moura et al. (2014): Unregulated hunting and genetic recovery from a severe population decline: the cautionary case of Bulgarian wolves. DOI: 10.1007/s10592-013-0547-y.A genetic linkage map of the canine genome has been developed by typing 150 microsatellite markers using 17 three-generation pedigrees, composed of 163 F2individuals. One hundred and thirty-nine markers were linked to at least one other marker with a lod score ≥ 3.0, identifying 30 linkage groups. The largest chromosome had 9 markers spanning 106.1 cM. The average distance between markers was 14.03 cM, and the map covers an estimated 2073 cM. Eleven markers were informative on the mapping panel, but were unlinked to any other marker. These likely represent single markers located on small, distinct canine chromosomes. This map will be the initial resource for mapping canine traits of interest and serve as a foundation for development of a comprehensive canine genetic map.
Abstract
Peltola & Heikkilä, Jari (2018): Outlaws or Protected? DNA, Hybrids, and Biopolitics in a Finnish Wolf-Poaching Case. DOI: 10.1163/15685306-12341509.European wolf (Canis lupus) populations have suffered extensive decline and range contraction due to anthropogenic culling. In Bulgaria, although wolves are still recovering from a severe demographic bottleneck in the 1970s, hunting is allowed with few constraints. A recent increase in hunting pressure has raised concerns regarding long-term viability. We thus carried out a comprehensive conservation genetic analysis using microsatellite and mtDNA markers. Our results showed high heterozygosity levels (0.654, SE 0.031) and weak genetic bottleneck signals, suggesting good recovery since the 1970s decline. However, we found high levels of inbreeding (F IS = 0.113, SE 0.019) and a N e/N ratio lower than expected for an undisturbed wolf population (0.11, 95 % CI 0.08–0.29). We also found evidence for hybridisation and introgression from feral dogs (C. familiaris) in 10 out of 92 wolves (9.8 %). Our results also suggest admixture between wolves and local populations of golden jackals (C. aureus), but less extensive as compared with the admixture with dogs. We detected local population structure that may be explained by fragmentation patterns during the 1970s decline and differences in local ecological characteristics, with more extensive sampling needed to assess further population substructure. We conclude that high levels of inbreeding and hybridisation with other canid species, which likely result from unregulated hunting, may compromise long-term viability of this population despite its current high genetic diversity. The existence of population subdivision warrants an assessment of whether separate management units are needed for different subpopulations. Our study highlights conservation threats for populations with growing numbers but subject to unregulated hunting.
Abstract
Pilot et al. (2018): Widespread, long-term admixture between grey wolves and domestic dogs across Eurasia and its implications for the conservation status of hybrids. DOI: 10.1111/eva.12595.By analyzing a 2015 Finnish court case on wolf poaching, we discuss how wild animals are categorized, gain legal status based on their species identification, and affect the categorization of humans either as poachers or hunters concerned about the genetic purity of the species. The court had to evaluate the reliability, accuracy, and relevance of scientific knowledge to distinguish “pure” wolves from hybrids. Dealing with complicated questions of canid species identification, the court decision took a position in the debate on what to conserve in a world which escapes simple categorizations. Hence, we interpret the case as an example of biopolitics, addressing the challenges and tensions of governing life by differentiating between valued and less valued, killable and threatened lifeforms, and human responsibilities towards them.
Abstract
Hybridisation between a domesticated species and its wild ancestor is an important conservation problem, especially if it results in the introgression of domestic gene variants into wild species. Nevertheless, the legal status of hybrids remains unregulated, partially because of the limited understanding of the hybridisation process and its consequences. The occurrence of hybridisation between grey wolves and domestic dogs is well documented from different parts of the wolf geographic range, but little is known about the frequency of hybridisation events, their causes and the genetic impact on wolf populations. We analysed 61K SNPs spanning the canid genome in wolves from across Eurasia and North America and compared that data to similar data from dogs to identify signatures of admixture. The haplotype block analysis, which included 38 autosomes and the X chromosome, indicated the presence of individuals of mixed wolf–dog ancestry in most Eurasian wolf populations, but less admixture was present in North American populations. We found evidence for male‐biased introgression of dog alleles into wolf populations, but also identified a first‐generation hybrid resulting from mating between a female dog and a male wolf. We found small blocks of dog ancestry in the genomes of 62% Eurasian wolves studied and melanistic individuals with no signs of recent admixed ancestry, but with a dog‐derived allele at a locus linked to melanism. Consequently, these results suggest that hybridisation has been occurring in different parts of Eurasia on multiple timescales and is not solely a recent phenomenon. Nevertheless, wolf populations have maintained genetic differentiation from dogs, suggesting that hybridisation at a low frequency does not diminish distinctiveness of the wolf gene pool. However, increased hybridisation frequency may be detrimental for wolf populations, stressing the need for genetic monitoring to assess the frequency and distribution of individuals resulting from recent admixture.