New insights into the genetic composition and phylogenetic relationship of wolves and dogs in the Iberian Peninsula

Pires, A. E., Amorim, I. R., Borges, C., Simões, F., Teixeira, T., Quaresma, A., ... & Matos, J. (2017). New insights into the genetic composition and phylogenetic relationship of wolves and dogs in the Iberian Peninsula. Ecology and Evolution.

This study investigates the gene pool of Portuguese autochthonous dog breeds and their wild counterpart, the Iberian wolf subspecies (Canis lupus signatus), using standard molecular markers. A combination of paternal and maternal molecular markers was used to investigate the genetic composition, genetic differentiation and genetic relationship of native Portuguese dogs and the Iberian wolf. A total of 196 unrelated dogs, including breed and village dogs from Portugal, and other dogs from Spain and North Africa, and 56 Iberian wolves (wild and captive) were analyzed for nuclear markers, namely Y chromosome SNPs, Y chromosome STR loci, autosomal STR loci, and a mitochondrial fragment of the control region I. Our data reveal new variants for the molecular markers and confirm significant genetic differentiation between Iberian wolf and native domestic dogs from Portugal. Based on our sampling, no signs of recent introgression between the two subspecies were detected. Y chromosome data do not reveal genetic differentiation among the analyzed dog breeds, suggesting they share the same patrilineal origin. Moreover, the genetic distinctiveness of the Iberian wolf from other wolf populations is further confirmed with the description of new mtDNA variants for this endemism. Our research also discloses new molecular markers for wolf and dog subspecies assignment, which might become particularly relevant in the case of forensic or noninvasive genetic studies. The Iberian wolf represents a relic of the once widespread wolf population in Europe and our study reveals that it is a reservoir of unique genetic diversity of the grey wolf, Canis lupus. These results stress the need for conservation plans that will guarantee the sustainability of this threatened top predator in Iberia.

Domestic dogs threaten endangered species worldwide

The bark side: domestic dogs threaten endangered species worldwide 

Humans and their canine companions share many close bonds. Wolves (Canis lupus) were the first animal domesticated by people, some time between 15,000 and 50,000 years ago. 

There are now an estimated 1 billion domestic dogs across their near-global distribution.

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Trophic overlap between wolves and free-ranging wolf× dog hybrids

Bassi, E., Canu, A., Firmo, I., Mattioli, L., Scandura, M., & Apollonio, M. (2017). Trophic overlap between wolves and free-ranging wolf× dog hybrids in the Apennine Mountains, Italy. Global Ecology and Conservation, 9, 39-49.

Hybridization between wolves (Canis lupus) and domestic dogs (Canis familiaris) can represent a threat to wild populations via genetic introgression and ecological competition. Therefore understanding the ecological role of hybrids may be crucial for developing appropriate conservation strategies.

The Italian wolf population has a peculiar genetic composition due to a long-lasting geographic isolation. Nowadays, however, its genetic integrity is threatened by the spread of canine genes as a result of the hybridization with stray dogs in the wild.

The aim of the present study was to gain insights into the ecological role of free-ranging wolf–dog hybrids by investigating their winter food habits in comparison with wolves in a mountain area of Central Italy. Levels of genetic introgression from the dogs were assessed in two adjacent areas occupied by up to five different packs by analyzing non-invasive samples and carcasses collected therein with a set of uniparental and bi-parental molecular markers.

The obtained results enabled us to classify the two areas as ‘hybrid’ and ‘wolf’ areas based on their level of genetic introgression.

Trophic niche and similarity/dissimilarity analyses did not detect significant difference in the diet between the two areas: in both of them, wild boar was the main prey, followed by roe deer. Furthermore, the same age/body mass classes of the two ungulates were selected by wolves and hybrids. Our findings confirmed wolf–dog hybrids as potential competitors for wolves. Further studies on other aspects of their biology and ecology are recommended in order to better estimate the impact of hybridization on natural wolf populations.

First evidence of hybridization between golden jackal and domestic dog

Galov, A., Fabbri, E., Caniglia, R., Arbanasić, H., Lapalombella, S., Florijančić, T., ... & Randi, E. (2015). First evidence of hybridization between golden jackal (Canis aureus) and domestic dog (Canis familiaris) as revealed by genetic markers. Royal Society Open Science, 2(12), 150450.

Male golden jackal–dog hybrid (60c) with black coat coloration (a)
and ears with rounded tip (b) (dog characteristics),
and forelimbs with partially joined digital pads of the
middle fingers (golden jackal characteristics) (c).

Interspecific hybridization is relatively frequent in nature and numerous cases of hybridization between wild canids and domestic dogs have been recorded. However, hybrids between golden jackals (Canis aureus) and other canids have not been described before. In this study, we combined the use of biparental (15 autosomal microsatellites and three major histocompatibility complex (MHC) loci) and uniparental (mtDNA control region and a Y-linked Zfy intron) genetic markers to assess the admixed origin of three wild-living canids showing anomalous phenotypic traits. Results indicated that these canids were hybrids between golden jackals and domestic dogs. One of them was a backcross to jackal and another one was a backcross to dog, confirming that golden jackal–domestic dog hybrids are fertile. The uniparental markers showed that the direction of hybridization, namely females of the wild species hybridizing with male domestic dogs, was common to most cases of canid hybridization. A melanistic 3bp-deletion at the K locus (β-defensin CDB103 gene), that was absent in reference golden jackal samples, but was found in a backcross to jackal with anomalous black coat, suggested its introgression from dogs via hybridization. Moreover, we demonstrated that MHC sequences, although rarely used as markers of hybridization, can be also suitable for the identification of hybrids, as long as haplotypes are exclusive for the parental species.



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Influence of hybridization on coyote range expansion

Ellington, E. H., & Murray, D. L. (2015). Influence of hybridization on animal space use: a case study using coyote range expansion. Oikos.

Hybridization between animal species is likely to increase as distributional and reproductive barriers continue to break down due to anthropogenically driven changes in habitat and climate. Yet, the influence of hybridization on ecological interactions and ecosystem function remains understudied. Animal space use, an important component of ecosystem dynamics, is a complex relationship between intrinsic factors, which hybridization can influence, and extrinsic factors, such as environmental heterogeneity. Using the coyote Canis latrans, a well-studied species with a long history of hybridization with wolves and dogs Canis spp., we sought to assess the influence of hybridization relative to environmental factors in determining animal space use. We conducted a meta-regression analysis of 67 datasets on coyote home range size across North America and generated models to predict coyote home range size. Climate (latitude) and environmental variability played important roles in determining patterns of coyote space use, likely through their influence on availability of prey resources. However, we found hybridization to be the preeminent factor driving variation in coyote space use, with non-introgressed populations having considerably smaller home ranges than those from within the Canis hybrid zone of eastern North America. This pattern was upheld despite the variation in environmental factors between areas inside and outside the Canis hybrid zone. Our findings suggest that hybridization may serve as an important factor affecting ecosystems, as hybrids may have altered space requirements, and presumably different niche dimensions, compared to parental species. This, in turn, may influence the role that particular species play within communities.

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An integrated assessment of the impact of wild dogs in Australia

Wicks, S., Mazur, K., Please, P., Ecker, S., & Buetre, B. (2014). An integrated assessment of the impact of wild dogs in Australia. ABARES Research report no. 14.4, Canberra.

Wild dogs are a significant pest animal in Australia. They are widespread in Queensland, the Northern Territory and much of Western Australia and South Australia, as well as being present in parts of New South Wales and Victoria. Wild dogs are known to have a significant detrimental effect on the agricultural sector (market impacts), but they also cause non-market impacts in terms of adverse social impacts and environmental damage. These impacts are described in more detail below.

 

Low gene flow between wolves and dogs in Iran

Aghbolaghi, M. A., Rezaei, H. R., Scandura, M., & Kaboli, M. (2014). Low gene flow between Iranian Grey Wolves (Canis lupus) and dogs documented using uniparental genetic markers. Zoology in the Middle East, 60(2), 95-106.
Wolves have the ability to live in different habitats. However, in recent years, in many areas wolf populations have drastically declined and some of them have disappeared. A major concern in the management of wolf populations is the hybridization between wolves and dogs. In some regions, in order to generate strong breeds of guard dogs, wolves and dogs are intentionally hybridized. In this study, gene flow between wolves and dogs in Iran was examined, using a combination of uniparental markers: the mitochondrial DNA control region and four Y chromosome microsatellites. The species of origin of each haplotype was attributed by phylogenetic analyses. A very limited number of haplotypes was shared, suggesting limited gene flow between wolves and dogs in Iran. However, possible factors promoting hybridization are still present in the country and should not be neglected in the future management of the wild species.

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Legal status of wolf-hybrids

Trouwborst, A. (2014). Exploring the legal status of wolf‐dog hybrids and other dubious animals: International and EU law and the wildlife conservation problem of hybridization with domestic and alien species. Review of European, Comparative & International Environmental Law.

Hybridization with domestic or alien species poses a threat to many species of wild fauna. However, hybridization is not explicitly addressed in the provisions of the principal international legal instruments on nature conservation. This article reviews the relevance, scope and substance of wildlife protection obligations under the Bern Convention on European Wildlife and Natural Habitats and the European Union's Habitats Directive with respect to this issue. The problem of wolf-dog hybridization is singled out as a case study. The article concludes that addressing hybridization through preventive and mitigation measures is in conformity with the obligations of States under the Convention and the Directive, and may indeed be essential in order to comply with these obligations. In the wolf-dog context, this includes dealing with feral and stray dogs and captive hybrids, and removing hybrid animals from the wild. At the same time, it appears that the national prohibitions on the killing and capturing of wolves and other strictly protected species, as prescribed by the Convention and the Directive, also cover free-ranging wolf-dog hybrids and similar hybrids living in the wild. This entails that the removal of such hybrid animals from the wild is subject to the rules concerning derogations from strict protection. These rules, however, do not appear to stand in the way of such removal. The article's central recommendation is for the Standing Committee of the Bern Convention and the European Commission to adopt express guidance concerning hybridization.

Black wolves in Italy

Apollonio, M., Mattioli, L., & Scandura, M. (2004). Occurrence of black wolves in the Northern Apennines, Italy. Acta theriologica, 49(2), 281-285.

The occurrence of black-coated individuals in wolf Canis lupus Linnaeus, 1758 populations is not surprising itself, but their presence in populations recovering from a severe numerical decline has been considered a possible sign of crossbreeding with the domestic dog. In the northern Apennines (Italy), black wolves occur at a non-negligible frequency. In a 3300 km² area, 22% of wolves observed and 23% of all dead wolves found were represented by animals with a completely black coat. One ‘black’ wolf belonging to the studied population was analysed by a set of microsatellite loci, and no trace of hybridization was found in its ancestry. This result induced us to consider the occurrence of a black phenotype in this area possibly derived from a natural combination of wolf alleles in coat colour determining genes, and not necessarily as the result of crossbreeding with the domestic form.


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Introgressive hybridization between dogs and wolves in Italy

Verardi, A., Lucchini, V., & Randi, E. (2006). Detecting introgressive hybridization between free‐ranging domestic dogs and wild wolves (Canis lupus) by admixture linkage disequilibrium analysis. Molecular Ecology, 15(10), 2845-2855.

Occasional crossbreeding between free-ranging domestic dogs and wild wolves (Canis lupus) has been detected in some European countries by mitochondrial DNA sequencing and genotyping unlinked microsatellite loci. Maternal and unlinked genomic markers, however, might underestimate the extent of introgressive hybridization, and their impacts on the preservation of wild wolf gene pools. In this study, we genotyped 220 presumed Italian wolves, 85 dogs and 7 known hybrids at 16 microsatellites belonging to four different linkage groups (plus four unlinked microsatellites). Population clustering and individual assignments were performed using a Bayesian procedure implemented in structure 2.1, which models the gametic disequilibrium arising between linked loci during admixtures, aiming to trace hybridization events further back in time and infer the population of origin of chromosomal blocks. Results indicate that (i) linkage disequilibrium was higher in wolves than in dogs; (ii) 11 out of 220 wolves (5.0%) were likely admixed, a proportion that is significantly higher than one admixed genotype in 107 wolves found previously in a study using unlinked markers; (iii) posterior maximum-likelihood estimates of the recombination parameter r revealed that introgression in Italian wolves is not recent, but could have continued for the last 70 (± 20) generations, corresponding to approximately 140–210 years. Bayesian clustering showed that, despite some admixture, wolf and dog gene pools remain sharply distinct (the average proportions of membership to wolf and dog clusters were Qw = 0.95 andQd = 0.98, respectively), suggesting that hybridization was not frequent, and that introgression in nature is counteracted by behavioural or selective constraints.


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Gene flow between wolf and dog in the Caucasus

Kopaliani, N., Shakarashvili, M., Gurielidze, Z., Qurkhuli, T., & Tarkhnishvili, D. (2014). Gene Flow Between Wolf and Shepherd Dog Populations in Georgia (Caucasus). Journal of Heredity, esu014.

Shepherd dog; first-generation hybrid; wolf 

(all from Kazbegi, Georgia).

Photo courtesy: D. Tarkhnishvili & N. Kopaliani

We studied the distribution of the mitochondrial DNA haplotypes and microsatellite genotypes at 8 loci in 102 gray wolves, 57 livestock guarding dogs, and 9 mongrel dogs from Georgia (Caucasus). Most of the studied dogs had mitochondrial haplotypes clustered with presumably East Asian dog lineages, and most of the studied wolves had the haplotypes clustered with European wolves, but 20% of wolves and 37% of dogs shared the same mitochondrial haplotypes. Bayesian inference with STRUCTURE software suggested that more than 13% of the studied wolves had detectable dog ancestry and more than 10% of the dogs had detectable wolf ancestry. About 2–3% of the sampled wolves and dogs were identified, with a high probability, as first-generation hybrids. These results were supported by the relatedness analysis, which showed that 10% of wolves and 20% of dogs had closest relatives from an opposite group. The results of the study suggest that wolf–dog hybridization is a common event in the areas where large livestock guarding dogs are held in a traditional way, and that gene flow between dogs and gray wolves was an important force influencing gene pool of dogs for millennia since early domestication events. This process may have been terminated 1) in areas outside the natural range of gray wolves and 2) since very recent time, when humans started to more tightly control contacts of purebred dogs.

Herd and shepherd dogs in Georgia

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Complex interactions between wolves and dogs

Lescureux, N., & Linnell, J. D. (2014). Warring brothers: The complex interactions between wolves (Canis lupus) and dogs (Canis familiaris) in a conservation context. Biological Conservation, 171, 232-245.

Although both wolves and dogs have been the subjects of numerous studies in many disciplines, the complex relationships between them have not yet been synthesized within a common review, and neither has it been placed in a holistic conservation context. Information and data are spread across numerous publications from different disciplines that rarely interact. Dogs have become the most common carnivore and their population is still increasing. In a context of wolf recovery in multi-use landscapes, there is a growing concern among conservationists for the potential negative impact of dogs on wolf conservation. With this paper we aim to review the numerous and complex interactions existing between wolves and dogs, using literature from disciplines as diverse as history, archeology, anthropology, genetics, ecology, and epidemiology in order to better understand the wolf–dog relationship and its potential impact on wolf conservation. Starting with their phylogenetic relationship and following a summary of the current knowledge on the dog’s ancestry we explore how dogs can represent a direct threat for wolves through hybridization, disease transfer and competition. The review highlights a number of ways in which dogs can impact wolf conservation, although a general lack of data and conclusive studies is a common theme that emerges for many topics. Then we analyse how dogs can mitigate human–wolf conflicts through their role as livestock guardians or wolf hunters. Finally we describe the complex phenomenon of wolf predation on dogs before discussing the wolf–dog relationships in general, with a special focus on including a more anthropological perspective. The review highlights the diversity of interactions between wolves and dogs, that can be both negative and positive for wolf conservation. However, more important than these direct impacts, the review highlights how the wolf–dog relationship challenges human attempts to construct simple dichotomies between wild and domestic, or between nature and culture. The borders between these concepts are in fact much more fluid and elusive than is often appreciated, and wolf conservation must adapt to this more complex reality.



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Early introgression of dog genes during re-expansion of wolf in Italy

Randi, E., Hulva, P., Fabbri, E., Galaverni, M., Galov, A., Kusak, J., Bigi, D., Černá Bolfíková, B., Smetanová, M. & Caniglia, R. (2014). Multilocus Detection of Wolf x Dog Hybridization in Italy, and Guidelines for Marker Selection. PLOS ONE, 9(1), e86409.

Hybridization and introgression can impact the evolution of natural populations. Several wild canid species hybridize in nature, sometimes originating new taxa. However, hybridization with free-ranging dogs is threatening the genetic integrity of grey wolf populations (Canis lupus), or even the survival of endangered species (e.g., the Ethiopian wolf C. simensis). Efficient molecular tools to assess hybridization rates are essential in wolf conservation strategies. We evaluated the power of biparental and uniparental markers (39 autosomal and 4 Y-linked microsatellites, a melanistic deletion at the β-defensin CBD103 gene, the hypervariable domain of the mtDNA control-region) to identify the multilocus admixture patterns in wolf x dog hybrids. We used empirical data from 2 hybrid groups with different histories: 30 presumptive natural hybrids from Italy and 73 Czechoslovakian wolfdogs of known hybrid origin, as well as simulated data. We assessed the efficiency of various marker combinations and reference samples in admixture analyses using 69 dogs of different breeds and 99 wolves from Italy, Balkans and Carpathian Mountains. Results confirmed the occurrence of hybrids in Italy, some of them showing anomalous phenotypic traits and exogenous mtDNA or Y-chromosome introgression. Hybridization was mostly attributable to village dogs and not strictly patrilineal. The melanistic β-defensin deletion was found only in Italian dogs and in putative hybrids. The 24 most divergent microsatellites (largest wolf-dog F_ST values) were equally or more informative than the entire panel of 39 loci. A smaller panel of 12 microsatellites increased risks to identify false admixed individuals. The frequency of F1 and F2 was lower than backcrosses or introgressed individuals, suggesting hybridization already occurred some generations in the past, during early phases of wolf expansion from their historical core areas. Empirical and simulated data indicated the identification of the past generation backcrosses is always uncertain, and a larger number of ancestry-informative markers is needed.


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Wolf's bottleneck and dog gene introgression in Bulgaria

Moura, A. E., Tsingarska, E., Dąbrowski, M. J., Czarnomska, S. D., Jędrzejewska, B., & Pilot, M. (2013). Unregulated hunting and genetic recovery from a severe population decline: the cautionary case of Bulgarian wolves.Conservation Genetics, 1-13. DOI 10.1007/s10592-013-0547-y

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

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BOOK: Free-Ranging Dogs and Wildlife Conservation

Gompper, M.E. (Ed.) 2013. Free-Ranging Dogs and Wildlife Conservation. Oxford University Press. 

Table of contents

Luigi Boitani: Foreword
Matthew E. Gompper: Introduction: Outlining the Ecological Influences of a Subsidized, Domesticated Predator
1: Matthew E. Gompper: The Dog-Human-Wildlife Interface: Assessing the Scope of the Problem
2: Euan G. Ritchie, Mike Letnic, Christopher R. Dickman and Abi Tamim Vanak: Dogs as Predators and Trophic Regulators
3: Abi Tamim Vanak, Christopher R. Dickman, Eduardo A. Silva-Rodriguez, James R. A. Butler and Euan G. Ritchie: Top-dogs and Under-dogs: Competition between Dogs and Sympatric Carnivores
4: Michael A. Weston and Theodore Stankowich: Dogs as Agents of Disturbance
5: James R.A. Butler, John D.C. Linnell, Damian Morrant, Vidya Athreya, Nicolas Lescureux and Adam Mckeown: Dog Eat Dog, Cat Eat Dog: Social-ecological Dimensions and Implications of Dog Predation by Wild Carnivores
6: Darryn Knobel, James R. A. Butler, Tiziana Lembo, Rob Critchlow and Matthew E. Gompper: Dogs, Disease, and Wildlife
7: Jennifer A. Leonard, Jorge Echegaray, Ettore Randi and Carles Vilà: Impact of Hybridization with Domestic Dogs on the Conservation of Wild Canids
8: Ryan H. Boyko and Adam R. Boyko: Dog Conservation and the Population Genetic Structure of Dogs
9: Kurt VerCauteren, Michael Lavelle, Thomas M. Gehring, Jean-Marc Landry and Laurie Marker: Dogs as Mediators of Conservation Conflicts
10: Deborah A. (Smith) Woollett, Aimee Hurt and Ngaio Richards: The Current and Future Roles of Free-ranging Detection Dogs in Conservation Efforts
11: Jeremy Koster and Andrew Noss: Hunting Dogs and the Extraction of Wildlife as a Resource
12: Kelly K. Miller, Euan G. Ritchie and Michael A. Weston: The Human Dimensions of Dog-Wildlife Interactions

Canis hybrids in Oklahoma

Freeman, R. C., & Shaw, J. H. (1979). Hybridization in Canis (Canidae) in Oklahoma. The Southwestern Naturalist, 24 (3) 485-499.

Fifteen cranial and dental measurements were taken from 138 wild Canis collected during 1975-76 and from 114 specimens collected from 1953-70. These were compared to known target populations of coyotes, red wolves, gray wolves, dogs, and coyote x dog hybrids by discriminant function and canonical variable analyses and were, along with weight and pelage color, used to assign each specimen. Measurements of current (1975-76) specimens were compared with those of older (1953-70) samples to test for temporal changes. Most current Oklahoma specimens were coyote-like, with 82.9 percent of the males and 78.6 percent of the females classified as coyotes. Evidence of coyote x dog hybridization was found in 14.6 and 10.7 percent of the males and females, respectively. Red wolf x coyote ancestry was evident in 2.4 percent of the males and 10.7 percent of the females. Temporal comparisons indicated consistent levels of hybridization except in southeastern Oklahoma, where red wolf influence is declining.

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Black wolves

Anderson, T. M., Candille, S. I., Musiani, M., Greco, C., Stahler, D. R., Smith, D. W., Padhukasahasram, B., Randi, E., Leonard, J.A., Bustamante, C.D., Ostrander,E.A., Tang, H., Wayne, R.K. & Barsh, G. S. (2009). Molecular and evolutionary history of melanism in North American gray wolves. Science, 323(5919), 1339-1343.

Morphological diversity within closely related species is an essential aspect of evolution and adaptation. Mutations in the Melanocortin 1 receptor (Mc1r) gene contribute to pigmentary diversity in natural populations of fish, birds, and many mammals. However, melanism in the gray wolf, Canis lupus, is caused by a different melanocortin pathway component, the K locus, that encodes a beta-defensin protein that acts as an alternative ligand for Mc1r. We show that the melanistic K locus mutation in North American wolves derives from past hybridization with domestic dogs, has risen to high frequency in forested habitats, and exhibits a molecular signature of positive selection. The same mutation also causes melanism in the coyote, Canis latrans, and in Italian gray wolves, and hence our results demonstrate how traits selected in domesticated species can influence the morphological diversity of their wild relatives.


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Introgression of domestic dog haplotype in coyote

Adams, J. R., Leonard, J. A., & Waits, L. P. (2003). Widespread occurrence of a domestic dog mitochondrial DNA haplotype in southeastern US coyotes.Molecular Ecology, 12(2), 541-546.

Sequence analysis of the mitochondrial DNA control region from 112 southeastern US coyotes (Canis latrans) revealed 12 individuals with a haplotype closely related to those in domestic dogs. Phylogenetic analyses grouped this new haplotype in the dog/grey wolf (Canis familiaris/Canis lupus) clade with 98% bootstrap support. These results demonstrate that a male coyote hybridized with a female dog, and female hybrid offspring successfully integrated into the coyote population. The widespread distribution of this haplotype from Florida to West Virginia suggests that the hybridization event occurred long ago before the southeastern USA was colonized by coyotes. However, it could have occurred in the southeastern USA before the main front of coyotes arrived in the area between male coyotes released for sport and a local domestic dog. The introgression of domestic dog genes into the southeastern coyote population does not appear to have substantially affected the coyote's genetic, morphological, or behavioural integrity. However, our results suggest that, contrary to previous reports, hybridization can occur between domestic and wild canids, even when the latter is relatively abundant. Therefore, hybridization may be a greater threat to the persistence of wild canid populations than previously thought.

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Life+ project on wolf-dog hybridisation in Italy

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Hybridisation of canids in Australia

Stephens, D. (2011). The molecular ecology of Australian wild dogs: hybridisation, gene flow and genetic structure at multiple geographic scales. PhD, The University of Western Australia, Perth.

Advances in molecular ecology, particularly over the past two decades, have allowed studies of populations to extend to increasingly broad geographic and temporal scales without sacrificing detail. Limitations on sample numbers and types are decreasing, as efficiency and techniques for extracting DNA from suboptimal sources (such as hair or scats) improve. In this thesis I use microsatellite DNA markers to produce the first study of population genetics in Australian wild dogs, including dingoes (Canis lupus dingo), feral domestic dogs (C. l. familiaris) and their hybrids. Dingoes are unique among the Australian vertebrate fauna because they were transported to the continent approximately 5,000 years ago.
They have therefore not been in the ecosystem on evolutionary timescales, but have been present much longer than other introduced species. Dingoes are Australia’s apex predator, and have spread across habitats from deserts to tropical forests, but are currently under threat of extinction due to widespread hybridisation with domestic dogs. The conservation of dingoes is a management priority in some areas, but in others they are actively persecuted to protect livestock from predation.
The research areas addressed in this thesis are: the type of genetic samples best suited to different questions in research on wild dogs; the locations of pure dingoes; the patterns of gene flow among individuals and groups; and the degree of variability in spatial ecology across their range. Research outcomes are also placed into the context of how they can inform the management of wild dogs. Comparison of three non-invasively collected DNA sources with each other and with an invasively collected source (DNA swabs) showed that non-invasive samples, particularly scats, can be an appropriate source of DNA for monitoring based on
identification of individual. The costs and time involved in quality control of noninvasive samples, however, make them a less attractive option for large-scale or population-level studies, which require more genetic markers. I therefore employed tissue samples sourced from culling programs to examine aspects of
gene flow at four geographic scales. At the continental scale, I assessed the level of interbreeding between dingoes and domestic dogs, using both established methodology and a Bayesian clustering approach. Both methods provided similar results, showing increased hybridisation in coastal areas, particularly the
southeast of Australia, but fewer hybrids in the inland areas with lower densities of human settlement. Because population structure may affect approaches to control of wild dogs and conservation of dingoes, I then examined the scale and pattern of genetic subdivision and relatedness in three regions: the Tanami desert in the northern central region of Australia; south Queensland on the east coast; and across the western third of the continent. Wild dogs showed unexpected patterns of population structure, with variations in the geographical extent and separation of clusters. Relationships and spatial ecology of wild dogs in the Tanami desert appeared to be strongly affected by human activity, particularly the presence of artificially abundant food resources. The wild dogs sampled in south Queensland and Western Australia showed distinct genetic clusters in the absence of geographic barriers, showing that Australian wild dogs display cryptic genetic
subdivision at a similar scale found in wolves in vastly different habitats. The findings of this study reinforce the variability found in Australian wild dogs previously demonstrated by studies of diet and movements, and provide a novel and comprehensive overview of gene flow both among wild dogs and between dingoes and domestic dogs.

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