Genetic structure in village dogs reveals a Central Asian domestication origin

Genetic structure and common ancestry expose the dingo-dog hybrid myth

The evolutionary history of canids has been shown to be complex, with hybridization and domestication confounding our understanding of speciation among various canid lineages. The dingo is a recent canid lineage that was completely isolated from other canids for over 5000 years on the Australian mainland, but the introduction of domestic dogs in 1788 has placed doubt on its independence, with recent studies highlighting hybridization between dingoes and domestic dogs. Using genomic single nucleotide polymorphism data from 434 Australian canid samples, we explicitly test for introgression between closely related canid groups and dingoes. We found no evidence of introgression between dingoes and domestic dogs and show that previous work has likely mischaracterized shared ancestral genetic variation as evidence for hybridization. Further, New Guinea Singing Dogs are the only canid group that significantly shared genetic variation with dingoes, which fits with our understanding of previous phylogenetic analyses. Despite more recent sympatric distributions with dogs, dingoes have likely maintained their independence since their arrival in Australia, even in areas with high lethal control, indicating that their evolutionary trajectory is currently being conserved. The future conservation of the dingo lineage will require policies that promote coexistence pathways between humans and dingoes that protect rangeland systems and the dingoes' evolutionary future.

Genomic reconstruction reveals impact of population management strategies on modern Galápagos dogs

Free-breeding dogs have occupied the Galápagos Islands at least since the 1830s; however, it was not until the 1900s that dog populations grew substantially, endangering wildlife and spreading disease.1,2,3,4 In 1981, efforts to control the population size of free-roaming dogs began.1 Yet, there exist large free-roaming dog populations on the islands of Isabela and Santa Cruz whose ancestry has never been assessed on a genome-wide scale. We thus performed a complete genomic analysis of the current Galápagos dog population, as well as historical Galápagos dogs sampled between 1969 and 2003, testing for population structure, admixture, and shared ancestry. Our dataset included samples from 187 modern and six historical Galápagos dogs, together with whole-genome sequences from over 2,000 modern purebred and village dogs. Our results indicate that modern Galápagos dogs are recently admixed with purebred dogs but show no evidence of a population bottleneck related to the culling. Additionally, identity-by-descent analyses reveal evidence of shared shepherd-dog ancestry in the historical dogs. Overall, our results demonstrate that the 1980s culling of dogs was ineffective in controlling population size and did little to reduce genetic diversity, instead producing a stable and expanding population with genomic signatures of modern purebred dogs. The insights from this study can be used to improve population control strategies for the Galápagos Islands and other endangered endemic communities.

A Variant-Centric Analysis of Allele Sharing in Dogs and Wolves

Canines are an important model system for genetics and evolution. Recent advances in sequencing technologies have enabled the creation of large databases of genetic variation in canines, but analyses of allele sharing among canine groups have been limited. We applied GeoVar, an approach originally developed to study the sharing of single nucleotide polymorphisms across human populations, to assess the sharing of genetic variation among groups of wolves, village dogs, and breed dogs. Our analysis shows that wolves differ from each other at an average of approximately 2.3 million sites while dogs from the same breed differ at nearly 1 million sites. We found that 22% of the variants are common across wolves, village dogs, and breed dogs, that ~16% of variable sites are common across breed dogs, and that nearly half of the differences between two dogs of different breeds are due to sites that are common in all clades. These analyses represent a succinct summary of allele sharing across canines and illustrate the effects of canine history on the apportionment of genetic variation.

Multiple ancestries and shared gene flow among modern livestock guarding dogs

Livestock guarding dogs (LGDs) have been used to protect livestock for millennia. While previous works suggested a single origin of modern LGDs, the degree and source of shared ancestry have not been tested. To address this, we generated genome-wide SNP data from 304 LGDs and combined it with public genomic data from 2,183 modern and 22 ancient dogs. Our findings reveal shared ancestry and extensive gene flow among modern LGD breeds which we attribute to historical livestock migrations. Additionally, admixture between LGDs and free-ranging dogs argues against reproductive isolation as a core mechanism for maintaining the specialized skills of LGDs. Finally, we identify two lineages within modern LGDs and uncover multiple ancestries tracing back to distinct Eurasian ancient dogs, concordant with the absence of a single ancestor. Overall, our work explores the complex evolutionary history of LGDs, offering valuable insights into how human and livestock co-migrations shaped this functional group.

Large-scale genomic analysis of the domestic dog informs biological discovery

Recent advances in genomics, coupled with a unique population structure and remarkable levels of variation, have propelled the domestic dog to new levels as a system for understanding fundamental principles in mammalian biology. Central to this advance are more than 350 recognized breeds, each a closed population that has undergone selection for unique features. Genetic variation in the domestic dog is particularly well characterized compared with other domestic mammals, with almost 3000 high-coverage genomes publicly available. Importantly, as the number of sequenced genomes increases, new avenues for analysis are becoming available. Herein, we discuss recent discoveries in canine genomics regarding behavior, morphology, and disease susceptibility. We explore the limitations of current data sets for variant interpretation, tradeoffs between sequencing strategies, and the burgeoning role of long-read genomes for capturing structural variants. In addition, we consider how large-scale collections of whole-genome sequence data drive rare variant discovery and assess the geographic distribution of canine diversity, which identifies Asia as a major source of missing variation. Finally, we review recent comparative genomic analyses that will facilitate annotation of the noncoding genome in dogs.

Historic dog Furs Unravel the Origin and Artificial Selection of Modern Nordic Lapphund and Elkhound dog Breeds

The origins and extreme morphological evolution of the modern dog breeds are poorly studied because the founder populations are extinct. Here, we analyse eight 100 to 200 years old dog fur samples obtained from traditional North Swedish clothing, to explore the origin and artificial selection of the modern Nordic Lapphund and Elkhound dog breeds. Population genomic analysis confirmed the Lapphund and Elkhound breeds to originate from the local dog population, and showed a distinct decrease in genetic diversity in agreement with intense breeding. We identified eleven genes under positive selection during the breed development. In particular, the MSRB3 gene, associated with breed-related ear morphology, was selected in all Lapphund and Elkhound breeds, and functional assays showed that a SNP mutation in the 3'UTR region suppresses its expression through miRNA regulation. Our findings demonstrate analysis of near-modern dog artifacts as an effective tool for interpreting the origin and artificial selection of the modern dog breeds.

Japanese wolves are most closely related to dogs and share DNA with East Eurasian dogs

Although the domestic dog's origin is still unclear, this lineage is believed to have been domesticated from an extinct population of gray wolves, which is expected to be more closely related to dogs than to other populations of gray wolves. Here, we sequence the whole genomes of nine Japanese wolves (7.5-100x: Edo to Meiji periods) and 11 modern Japanese dogs and analyze them together with those from other populations of dogs and wolves. A phylogenomic tree shows that, among the gray wolves, Japanese wolves are closest to the dog, suggesting that the ancestor of dogs is closely related to the ancestor of the Japanese wolf. Based on phylogenetic and geographic relationships, the dog lineage has most likely originated in East Asia, where it diverged from a common ancestor with the Japanese wolf. Since East Eurasian dogs possess Japanese wolf ancestry, we estimate an introgression event from the ancestor of the Japanese wolf to the ancestor of the East Eurasian dog that occurred before the dog's arrival in the Japanese archipelago.

Effects of neoadjuvant zoledronate and radiation therapy on cell survival, cell cycle distribution, and clinical status in canine osteosarcoma

Introduction

Zoledronic acid (ZOL) is a third-generation bisphosphonate with a higher affinity for bone resorption areas than earlier bisphosphonates (i.e., pamidronate, PAM). In human medicine, ZOL provides improved bone pain relief and prolonged time to skeletal-related events compared to its older generational counterparts. Preclinical studies have investigated its role as an anti-neoplastic agent, both independently and synergistically, with radiation therapy (RT). ZOL and RT act synergistically in several neoplastic human cell lines: prostate, breast, osteosarcoma, and fibrosarcoma. However, the exact mechanism of ZOL's radiosensitization has not been fully elucidated.

Methods

We investigated ZOL's ability to induce apoptosis in canine osteosarcoma cell lines treated with various doses of megavoltage external beam radiotherapy. Second, we evaluated cell cycle arrest in ZOL-treated cells to assess several neo-adjuvant time points. Finally, we treated 20 dogs with naturally occurring appendicular OS with 0.1 mg/kg ZOL IV 24 h before receiving 8 Gy of RT (once weekly fraction x 4 weeks).

Results

We found that apoptosis was increased in all ZOL-treated cell lines compared to controls, and the combination of ZOL and RT resulted in dissimilar apoptosis between Abrams and D-17 and HMPOS cell lines. Cell cycle arrest (G2/M phase) was minimal and variable between cell lines but perhaps greatest at 48 h post-ZOL treatment. Only 10% of dogs treated with ZOL and RT developed pathologic fractures, compared to 44% of dogs historically treated with PAM and RT (p = 0.027).

Discussion

ZOL and RT appear to be a well-tolerated combination treatment scheme for non-surgical candidates; future studies must elucidate the ideal timing of ZOL.

A purebred South American breed showing high effective population size and independent breed ancestry: The Chilean Terrier

The Chilean Terrier is a known breed in Chile that has not been genetically assessed despite its distinctive color patterns, agility, and hardiness across the diversity of climates encountered within the Chilean landscape. The population structure and its relatedness with other breeds, as well as the actual origin of the breed, remain unknown. We estimated several population parameters using samples from individuals representing the distribution of the Chilean Terrier across the country. By utilizing the Illumina HD canine genotyping array, we computed the effective population size (Ne ), individual inbreeding, and relatedness to evaluate the genetic diversity of the breed. The results show that linkage disequilibrium was relatively low and decayed rapidly; in fact, Ne was very high when compared to other breeds, and similar to other American indigenous breeds (such as the Chihuahua with values of Ne near 500). These results are in line with the low estimates of genomic inbreeding and relatedness and the relatively large number of effective chromosome segments (Me  = 2467) obtained using the properties of the genomic relationship matrix. Between population analysis (cross-population extended haplotype homozygosity, di ) with other breeds such as the Jack Russell Terrier, the Peruvian-Inca Orchid, and the Chihuahua suggested that candidate regions harboring FGF5, PAX3, and ASIP, probably explained some morphological traits, such as the distinctive color pattern characteristic of the breed. When considering Admixture estimates and phylogenetic analysis, together with other breeds of American and European origin, the Chilean Terrier does not have a recent European ancestry. Overall, the results suggest that the breed has evolved independently in Chile from other terrier breeds, from an unknown European terrier ancestor.

Genomic selection analysis of morphological and adaptation traits in Chinese indigenous dog breeds

The significant morphological differences and abundant germplasm resources of Chinese indigenous dog breeds can be attributed to the diverse geographical environment, including plateaus, mountains, and a long history of raising dogs. The combination of both natural and artificial selection during the past several thousand years has led to hundreds of dog breeds with distinct morphological traits and environmental adaptations. China is one of the earliest countries to domesticate dogs and there are more than 50 ancient indigenous dog breeds. In this study, the run of homozygosity (ROH) and proportion of the autosomal genome covered by ROHs (FROH) were calculated for 10 dog breeds that are the most representative Chinese indigenous dogs based on 170K SNP microarray. The results of FROH showed that the Chuandong hound dogs (HCSSC) have the highest level of inbreeding among the tested breeds. The inbreeding in HCSSC occurred more recently than the Liangshan dogs (SCLSQ) dogs because of more numbers of long ROHs in HCSSC dogs, and the former also have higher inbreeding degree. In addition, there are significant differences in the inbreeding degree among different subpopulations of the same breed, such as the Thin dogs from Shaanxi and Shandong province. To explore genome-wide selection signatures among different breeds, including coat color, ear shape, and altitude adaptability, we performed genome selection analyses of FST and cross population extended haplotype homozygosity (XP-EHH). For the coat color, the FST analysis between Xiasi dogs (XSGZ) and HCSSC dogs was performed and identified multiple genes involved in coat color, hair follicle, and bone development, including MC1R, KITLG, SOX5, RSPO2, and TBX15. For the plateau adaptability, we performed FST and XP-EHH analyses between dogs from Tibet (Tibetan Mastiffs and Nyingchi dogs) and plain regions (Guangxi Biwei dogs GXBWQ and Guandong Sharpei dogs). The results showed the EPAS1 gene in dogs from Tibet undergo strong selection. Multiple genes identified for selection signals based on different usage of dogs. Furthermore, the results of ear shape analyses showed that MSRB3 was likely to be the main gene causing the drop ear of domestic dogs. Our study provides new insights into further understanding of Chinese indigenous dogs.

Origin and population structure of native dog breeds in the Korean peninsula and East Asia

To study the ancestry and phylogenetic relationships of native Korean dog breeds to other Asian dog populations, we analyzed nucleotide variations in whole-genome sequences of 205 canid individuals. Sapsaree, Northern Chinese indigenous dog, and Tibetan Mastiff were largely related to West Eurasian ancestry. Jindo, Donggyeongi, Shiba, Southern Chinese indigenous (SCHI), Vietnamese indigenous dogs (VIET), and Indonesian indigenous dogs were related to Southeast and East Asian ancestry. Among East Asian dog breeds, Sapsaree presented the highest haplotype sharing with German Shepherds, indicating ancient admixture of European ancestry to modern East Asian dog breeds. SCHI showed greater haplotype sharing with New Guinea singing dogs, VIET, and Jindo than with other Asian breeds. The predicted divergence time of East Asian populations from their common ancestor was approximately 2,000 to 11,000 years ago. Our results expand understanding of the genetic history of dogs in the Korean peninsula to the Asian continent and Oceanic region.

Being a Dog: A Review of the Domestication Process

The process of canine domestication represents certainly one of the most interesting questions that evolutionary biology aims to address. A "multiphase" view of this process is now accepted, with a first phase during which different groups of wolves were attracted by the anthropogenic niche and a second phase characterized by the gradual establishment of mutual relationships between wolves and humans. Here, we provide a review of dog (Canis familiaris) domestication, highlighting the ecological differences between dogs and wolves, analyzing the molecular mechanisms which seem to have influenced the affiliative behaviors first observed in Belyaev's foxes, and describing the genetics of ancient European dogs. Then, we focus on three Mediterranean peninsulas (Balkan, Iberian and Italian), which together represent the main geographic area for studying canine domestication dynamics, as it has shaped the current genetic variability of dog populations, and where a well-defined European genetic structure was pinpointed through the analysis of uniparental genetic markers and their phylogeny.

Companion animal organoid technology to advance veterinary regenerative medicine

First year medical and veterinary students are made very aware that drugs can have very different effects in various species or even in breeds of one specific species. On the other hand, the “One Medicine” concept implies that therapeutic and technical approaches are exchangeable between man and animals. These opposing views on the (dis)similarities between human and veterinary medicine are magnified in regenerative medicine. Regenerative medicine promises to stimulate the body's own regenerative capacity via activation of stem cells and/or the application of instructive biomaterials. Although the potential is enormous, so are the hurdles that need to be overcome before large scale clinical implementation is realistic. It is in the advancement of regenerative medicine that veterinary regenerative medicine can play an instrumental and crucial role. This review describes the discovery of (adult) stem cells in domesticated animals, mainly cats and dogs. The promise of cell-mediated regenerative veterinary medicine is compared to the actual achievements, and this will lead to a set of unanswered questions (controversies, research gaps, potential developments in relation to fundamental, pre-clinical, and clinical research). For veterinary regenerative medicine to have impact, either for human medicine and/or for domesticated animals, answering these questions is pivotal.

The dogs of Chernobyl: Demographic insights into populations inhabiting the nuclear exclusion zone

The 1986 Chernobyl nuclear disaster initiated a series of catastrophic events resulting in long-term and widespread environmental contamination. We characterize the genetic structure of 302 dogs representing three free-roaming dog populations living within the power plant itself, as well as those 15 to 45 kilometers from the disaster site. Genome-wide profiles from Chernobyl, purebred and free-breeding dogs, worldwide reveal that the individuals from the power plant and Chernobyl City are genetically distinct, with the former displaying increased intrapopulation genetic similarity and differentiation. Analysis of shared ancestral genome segments highlights differences in the extent and timing of western breed introgression. Kinship analysis reveals 15 families, with the largest spanning all collection sites within the radioactive exclusion zone, reflecting migration of dogs between the power plant and Chernobyl City. This study presents the first characterization of a domestic species in Chernobyl, establishing their importance for genetic studies into the effects of exposure to long-term, low-dose ionizing radiation.

Canine transmissible venereal tumor - From general to molecular characteristics: A review

Cancer is a group of complex diseases resulting from the accumulation of genetic and epigenetic changes affecting control and activity of several genes, especially those involved in cell differentiation and growth processes, leading to an abnormal proliferation. When the disease reaches an advanced stage, cancer can lead to metastasis in other organs. Interestingly, recent studies have shown that some types of cancer spread not only through the body, but also can be transmitted among individuals. Therefore, these cancers are known as transmissible tumors. Among the three types of transmissible tumors that occur in nature, the canine transmissible venereal tumor (CTVT) is known as the oldest cancer in the world, since it was originated from a single individual 11 000 years ago. The disease has a worldwide distribution, and its occurrence has been documented since 1810. The CTVT presents three types of cytomorphological classification: lymphocytoid type, mixed type, and plasmacytoid type, the latter being chemoresistant due to overexpression of the ABCB1 gene, and consequently increase of the P-glycoprotein. More knowledge about the epidemiology and evolution of CTVT may help to elucidate the pathway and form of the global spread of the disease.

Kazakh national dog breed Tazy: What do we know?

The Tazy or Kazakh National sighthound has been officially recognized as the national heritage of Kazakhstan. Comprehensive genetic studies of genetic diversity and population structure that could be used for selection and conservation of this unique dog breed have not been conducted so far. The aim of this study was to determine the genetic structure of the Tazy using microsatellite and SNP markers and to place the breed in the context of the world sighthound breeds. Our results showed that all 19 microsatellite loci examined were polymorphic. The observed number of alleles in the Tazy population varied from 6 (INU030 locus) to 12 (AHT137, REN169D01, AHTh260, AHT121, and FH2054 loci) with a mean of 9.778 alleles per locus. The mean number of effective alleles was 4.869 and ranged from 3.349 f to 4.841. All markers were highly informative (PIC values greater than 0.5) and ranged from 0.543 (REN247M23 locus) to 0.865 (AHT121 locus). The observed and expected heterozygosities in a total population were 0.748 and 0.769 and ranged from 0.746 to 0.750 and 0.656 to 0.769, respectively. Overall, the results confirmed that the Tazy breed has a high level of genetic diversity, no significant inbreeding, and a specific genetic structure. Three gene pools underlie the genetic diversity of the Tazy breed. SNP analysis using the CanineHD SNP array, which contains more than 170,000 SNP markers, showed that the Tazy breed is distinct from other sighthound breeds and genetically related to ancient eastern sighthound breeds sharing the same branch with the Afghan Hound and the Saluki. The results, together with archeological findings, confirm the ancient origin of the breed. The findings can be used for the conservation and international registration of the Tazy dog breed.

Genetics of randomly bred cats support the cradle of cat domestication being in the Near East

Cat domestication likely initiated as a symbiotic relationship between wildcats (Felis silvestris subspecies) and the peoples of developing agrarian societies in the Fertile Crescent. As humans transitioned from hunter-gatherers to farmers ~12,000 years ago, bold wildcats likely capitalized on increased prey density (i.e., rodents). Humans benefited from the cats' predation on these vermin. To refine the site(s) of cat domestication, over 1000 random-bred cats of primarily Eurasian descent were genotyped for single-nucleotide variants and short tandem repeats. The overall cat population structure suggested a single worldwide population with significant isolation by the distance of peripheral subpopulations. The cat population heterozygosity decreased as genetic distance from the proposed cat progenitor's (F.s. lybica) natural habitat increased. Domestic cat origins are focused in the eastern Mediterranean Basin, spreading to nearby islands, and southernly via the Levantine coast into the Nile Valley. Cat population diversity supports the migration patterns of humans and other symbiotic species.

The genomic landscape of canine osteosarcoma cell lines reveals conserved structural complexity and pathway alterations

The characterization of immortalized canine osteosarcoma (OS) cell lines used for research has historically been based on phenotypic features such as cellular morphology and expression of bone specific markers. With the increasing use of these cell lines to investigate novel therapeutic approaches prior to in vivo translation, a much more detailed understanding regarding the genomic landscape of these lines is required to ensure accurate interpretation of findings. Here we report the first whole genome characterization of eight canine OS cell lines, including single nucleotide variants, copy number variants and other structural variants. Many alterations previously characterized in primary canine OS tissue were observed in these cell lines, including TP53 mutations, MYC copy number gains, loss of CDKN2A, PTEN, DLG2, MAGI2, and RB1 and structural variants involving SETD2, DLG2 and DMD. These data provide a new framework for understanding how best to incorporate in vitro findings generated using these cell lines into the design of future clinical studies involving dogs with spontaneous OS.

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.

Genetic Origins of the Two Canis lupus familiaris (Dog) Freight Dog Populations

Despite periodic drops in popularity, Arctic sled dogs continue to play a vital role in northern societies, providing both freight transit and recreational race activities. In this study, we selected the Mackenzie River Husky, a freight dog of complex history, and the Chinook, an American Kennel Club recognized freight dog breed whose heritage reportedly overlaps that of the MKRH, for detailed population analysis. We tested each to determine their component breeds and used admixture analysis to ascertain their population structure. We utilized haplotype analysis to identify genomic regions shared between each population and their founding breeds. Our data show that the Alaskan Malamutes and modern Greenland sled dog contributed to both populations, but there are also unexpected contributions from the German Shepherd dog and Collie. We used haplotype analysis to identify genomic regions nearing fixation in population type and identify provocative genes in each region. Finally, in response to recent reports regarding the importance of dietary lipid genes in Arctic dogs, we analyzed 8 such genes in a targeted analysis observing signatures of selection in both populations at the MLXIPL gene loci. These data highlight the genetic routes that breeds of similar function have taken toward their occupation as successful sled dogs.

Genetic and molecular Omp25 analyses from worldwide Brucella canis strains: Possible mutational influences in protein function

Brucella canis is responsible for canine brucellosis, a neglected zoonotic disease. The omp25 gene has been described as an important marker for Brucella intra-species differentiation, in addition to the ability to interact with the host immune system. Therefore, this study investigated the omp25 sequence from B. canis strains associated to a phylogenetic characterization and the unveiling of the molecular structure. In vitro analyses comprised DNA extraction, PCR, and sequencing of omp25 from 19 B. canis strains. Moreover, in silico analyses were performed at nucleotide level for phylogenetic characterization and evolutionary history of B. canis omp25 gene; and in amino acid level including modeling, dynamics, and epitope prediction of B. canis Omp25 protein. Here, we identified a new mutation, L109P, which diverges the worldwide omp25 sequences in two large branches. Interestingly, this mutation appears to have epidemiology importance, based on a geographical distribution of B. canis strains. Structural and molecular dynamics analyses of Omp25 revealed that Omp25L109P does not sustain its native β-barrel. Likewise, the conformation of B-cell epitope on the mutated region was changed in Omp25L109P protein. Even without an evolutive marker, the new identified mutation appears to affect the basic function of B. canis Omp25 protein, which could indicate virulence adaptation for some B. canis strains in a context of geographical disposition.

Isolierte bilaterale kranielle Hundebissverletzung bei einem Neugeborenen

Durch Hundeangriffe können lebensgefährliche Verletzungen verursacht werden. Die Lokalisationen von Hundebissen korrelieren mit dem Alter und den motorischen Fähigkeiten des Opfers. Bei Kindern unter 6 Jahren finden sich im Vergleich zu Erwachsenen und älteren Kindern häufiger schwere Bisswunden, v. a. im Kopf-Hals-Bereich. Es wird der Fall eines 20 Tage alten Neugeborenen mit einer schweren Form der Osteogenesis imperfecta vorgestellt, das mit 2 Hunden allein gelassen und attackiert wurde und eine isolierte, bilaterale Kopfschwartenverletzung und intrakranielle Verletzungen erlitt. Besonderheiten von Hundebissen werden mit besonderem Augenmerk auf Säuglinge und Kinder diskutiert. Isolierte schwere Kopfverletzungen nach Hundebissen sind ein seltenes Phänomen.

Tracing the Origin of the RSPO2 Long-Hair Allele and Epistatic Interaction between FGF5 and RSPO2 in Sapsaree Dog

Genetic analysis of the hair-length of Sapsaree dogs, a Korean native dog breed, showed a dominant mode of inheritance for long hair. Genome-Wide Association Study (GWAS) analysis and subsequent Mendelian segregation analysis revealed an association between OXR1, RSPO2, and PKHD1L1 on chromosome 13 (CFA13). We identified the previously reported 167 bp insertion in RSPO2 3’ untranslated region as a causative mutation for hair length variations. The analysis of 118 dog breeds and wolves revealed the selection signature on CFA13 in long-haired breeds. Haplotype analysis showed the association of only a few specific haplotypes to the breeds carrying the 167 bp insertion. The genetic diversity in the neighboring region linked to the insertion was higher in Sapsarees than in other Asian and European dog breeds carrying the same variation, suggesting an older history of its insertion in the Sapsaree genome than in that of the other breeds analyzed in this study. Our results show that the RSPO2 3’ UTR insertion is responsible for not only the furnishing phenotype but also determining the hair length of the entire body depending on the genetic background, suggesting an epistatic interaction between FGF5 and RSPO2 influencing the hair-length phenotype in dogs.

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.

Best practices for analyzing imputed genotypes from low-pass sequencing in dogs

Although DNA array-based approaches for genome-wide association studies (GWAS) permit the collection of thousands of low-cost genotypes, it is often at the expense of resolution and completeness, as SNP chip technologies are ultimately limited by SNPs chosen during array development. An alternative low-cost approach is low-pass whole genome sequencing (WGS) followed by imputation. Rather than relying on high levels of genotype confidence at a set of select loci, low-pass WGS and imputation rely on the combined information from millions of randomly sampled low-confidence genotypes. To investigate low-pass WGS and imputation in the dog, we assessed accuracy and performance by downsampling 97 high-coverage (> 15×) WGS datasets from 51 different breeds to approximately 1× coverage, simulating low-pass WGS. Using a reference panel of 676 dogs from 91 breeds, genotypes were imputed from the downsampled data and compared to a truth set of genotypes generated from high-coverage WGS. Using our truth set, we optimized a variant quality filtering strategy that retained approximately 80% of 14 M imputed sites and lowered the imputation error rate from 3.0% to 1.5%. Seven million sites remained with a MAF > 5% and an average imputation quality score of 0.95. Finally, we simulated the impact of imputation errors on outcomes for case-control GWAS, where small effect sizes were most impacted and medium-to-large effect sizes were minorly impacted. These analyses provide best practice guidelines for study design and data post-processing of low-pass WGS-imputed genotypes in dogs.

Ancient Faunal History Revealed by Interdisciplinary Biomolecular Approaches

Starting four decades ago, studies have examined the ecology and evolutionary dynamics of populations and species using short mitochondrial DNA fragments and stable isotopes. Through technological and analytical advances, the methods and biomolecules at our disposal have increased significantly to now include lipids, whole genomes, proteomes, and even epigenomes. At an unprecedented resolution, the study of ancient biomolecules has made it possible for us to disentangle the complex processes that shaped the ancient faunal diversity across millennia, with the potential to aid in implicating probable causes of species extinction and how humans impacted the genetics and ecology of wild and domestic species. However, even now, few studies explore interdisciplinary biomolecular approaches to reveal ancient faunal diversity dynamics in relation to environmental and anthropogenic impact. This review will approach how biomolecules have been implemented in a broad variety of topics and species, from the extinct Pleistocene megafauna to ancient wild and domestic stocks, as well as how their future use has the potential to offer an enhanced understanding of drivers of past faunal diversity on Earth.

Genetic inference of the mating system of free-ranging domestic dogs

Domestication has greatly changed the social and reproductive behavior of dogs relative to that of wild members of the genus Canis, which typically exhibit social monogamy and extended parental care. Unlike a typical gray wolf pack that consists of a single breeding pair and their offspring from multiple seasons, a group of free-ranging dogs (FRDs) can include multiple breeding individuals of both sexes. To understand the consequences of this shift in reproductive behavior, we reconstructed the genetic pedigree of an FRD population and assessed the kinship patterns in social groups, based on genome-wide single-nucleotide polymorphism genotypes. Consistent with behavioral observations, the mating system of the study population was characterized by polygynandry. Instead of the discreet family units observed in wolves, FRDs were linked by a network of kinship relationships that spread across packs. However, we also observed reproduction of the same male-female pairs in multiple seasons, retention of adult offspring in natal packs, and dispersal between neighboring packs-patterns in common with wolves. Although monogamy is the predominant mating system in wolves, polygyny and polyandry are occasionally observed in response to increased food availability. Thus, polygynandry of domestic dogs was likely influenced by the shift in ecological niche from an apex predator to a human commensal.

Dog domestication and the dual dispersal of people and dogs into the Americas

Advances in the isolation and sequencing of ancient DNA have begun to reveal the population histories of both people and dogs. Over the last 10,000 y, the genetic signatures of ancient dog remains have been linked with known human dispersals in regions such as the Arctic and the remote Pacific. It is suspected, however, that this relationship has a much deeper antiquity, and that the tandem movement of people and dogs may have begun soon after the domestication of the dog from a gray wolf ancestor in the late Pleistocene. Here, by comparing population genetic results of humans and dogs from Siberia, Beringia, and North America, we show that there is a close correlation in the movement and divergences of their respective lineages. This evidence places constraints on when and where dog domestication took place. Most significantly, it suggests that dogs were domesticated in Siberia by ∼23,000 y ago, possibly while both people and wolves were isolated during the harsh climate of the Last Glacial Maximum. Dogs then accompanied the first people into the Americas and traveled with them as humans rapidly dispersed into the continent beginning ∼15,000 y ago.

Czechoslovakian Wolfdog Genomic Divergence from Its Ancestors Canis lupus, German Shepherd Dog, and Different Sheepdogs of European Origin

This study focused on the genomic differences between the Czechoslovakian wolfdog (CWD) and its ancestors, the Grey wolf (GW) and German Shepherd dog. The Saarloos wolfdog and Belgian Shepherd dog were also included to study the level of GW genetics retained in the genome of domesticated breeds. The dataset consisted of 131 animals and 143,593 single nucleotide polymorphisms (SNPs). The effects of demographic history on the overall genome structure were determined by screening the distribution of the homozygous segments. The genetic variance distributed within and between groups was quantified by genetic distances, the FST index, and discriminant analysis of principal components. Fine-scale population stratification due to specific morphological and behavioural traits was assessed by principal component and factorial analyses. In the CWD, a demographic history effect was manifested mainly in a high genome-wide proportion of short homozygous segments corresponding to a historical load of inbreeding derived from founders. The observed proportion of long homozygous segments indicated that the inbreeding events shaped the CWD genome relatively recently compared to other groups. Even if there was a significant increase in genetic similarity among wolf-like breeds, they were genetically separated from each other. Moreover, this study showed that the CWD genome carries private alleles that are not found in either wolves or other dog breeds analysed in this study.

Variants That Differentiate Wolf and Dog Populations Are Enriched in Regulatory Elements

Research on the genetics of domestication most often focuses on the protein-coding exons. However, exons cover only a minor part (1–2%) of the canine genome, whereas functional mutations may be located also in regions beyond the exome, in regulatory regions. Therefore, a large proportion of phenotypical differences between dogs and wolves may remain genetically unexplained. In this study, we identified variants that have high allelic frequency differences (i.e., highly differentiated variants) between wolves and dogs across the canine genome and investigated the potential functionality. We found that the enrichment of highly differentiated variants was substantially higher in promoters than in exons and that such variants were enriched also in enhancers. Several enriched pathways were identified including oxytocin signaling, carbohydrate digestion and absorption, cancer risk, and facial and body features, many of which reflect phenotypes of potential importance during domestication, including phenotypes of the domestication syndrome. The results highlight the importance of regulatory mutations during dog domestication and motivate the functional annotation of the noncoding part of the canine genome.

Copy number variation underlies complex phenotypes in domestic dog breeds and other canids

Extreme phenotypic diversity, a history of artificial selection, and socioeconomic value make domestic dog breeds a compelling subject for genomic research. Copy number variation (CNV) is known to account for a significant part of inter-individual genomic diversity in other systems. However, a comprehensive genome-wide study of structural variation as it relates to breed-specific phenotypes is lacking. We have generated whole genome CNV maps for more than 300 canids. Our data set extends the canine structural variation landscape to more than 100 dog breeds, including novel variants that cannot be assessed using microarray technologies. We have taken advantage of this data set to perform the first CNV-based genome-wide association study (GWAS) in canids. We identify 96 loci that display copy number differences across breeds, which are statistically associated with a previously compiled set of breed-specific morphometrics and disease susceptibilities. Among these, we highlight the discovery of a long-range interaction involving a CNV near MED13L and TBX3, which could influence breed standard height. Integration of the CNVs with chromatin interactions, long noncoding RNA expression, and single nucleotide variation highlights a subset of specific loci and genes with potential functional relevance and the prospect to explain trait variation between dog breeds.

The impact of identity by descent on fitness and disease in dogs

Dogs and humans have coexisted together for thousands of years, but it was not until the Victorian Era that humans practiced selective breeding to produce the modern standards we see today. Strong artificial selection during the breed formation period has simplified the genetic architecture of complex traits and caused an enrichment of identity-by-descent (IBD) segments in the dog genome. This study demonstrates the value of IBD segments and utilizes them to infer the recent demography of canids, predict case-control status for complex traits, locate regions of the genome potentially linked to inbreeding depression, and to identify understudied breeds where there is potential to discover new disease-associated variants.

Domestic dogs have experienced population bottlenecks, recent inbreeding, and strong artificial selection. These processes have simplified the genetic architecture of complex traits, allowed deleterious variation to persist, and increased both identity-by-descent (IBD) segments and runs of homozygosity (ROH). As such, dogs provide an excellent model for examining how these evolutionary processes influence disease. We assembled a dataset containing 4,414 breed dogs, 327 village dogs, and 380 wolves genotyped at 117,288 markers and data for clinical and morphological phenotypes. Breed dogs have an enrichment of IBD and ROH, relative to both village dogs and wolves, and we use these patterns to show that breed dogs have experienced differing severities of bottlenecks in their recent past. We then found that ROH burden is associated with phenotypes in breed dogs, such as lymphoma. We next test the prediction that breeds with greater ROH have more disease alleles reported in the Online Mendelian Inheritance in Animals (OMIA). Surprisingly, the number of causal variants identified correlates with the popularity of that breed rather than the ROH or IBD burden, suggesting an ascertainment bias in OMIA. Lastly, we use the distribution of ROH across the genome to identify genes with depletions of ROH as potential hotspots for inbreeding depression and find multiple exons where ROH are never observed. Our results suggest that inbreeding has played a large role in shaping genetic and phenotypic variation in dogs and that future work on understudied breeds may reveal new disease-causing variation.

Genomic variation, population history and within-archipelago adaptation between island bird populations

Oceanic island archipelagos provide excellent models to understand evolutionary processes. Colonization events and gene flow can interact with selection to shape genetic variation at different spatial scales. Landscape-scale variation in biotic and abiotic factors may drive fine-scale selection within islands, while long-term evolutionary processes may drive divergence between distantly related populations. Here, we examine patterns of population history and selection between recently diverged populations of the Berthelot's pipit (Anthus berthelotii), a passerine endemic to three North Atlantic archipelagos. First, we use demographic trees and f3 statistics to show that genome-wide divergence across the species range is largely shaped by colonization and bottlenecks, with evidence of very weak gene flow between populations. Then, using a genome scan approach, we identify signatures of divergent selection within archipelagos at single nucleotide polymorphisms (SNPs) in genes potentially associated with craniofacial development and DNA repair. We did not detect within-archipelago selection at the same SNPs as were detected previously at broader spatial scales between archipelagos, but did identify signatures of selection at loci associated with similar biological functions. These findings suggest that similar ecological factors may repeatedly drive selection between recently separated populations, as well as at broad spatial scales across varied landscapes.

A publicly available repository of ROH islands reveals signatures of selection in different livestock and pet species

BACKGROUND

Runs of homozygosity (ROH) have become the state-of-the-art method for analysis of inbreeding in animal populations. Moreover, ROH are suited to detect signatures of selection via ROH islands and are used in other applications, such as genomic prediction and genome-wide association studies (GWAS). Currently, a vast amount of single nucleotide polymorphism (SNP) data is available online, but most of these data have never been used for ROH analysis. Therefore, we performed a ROH analysis on large medium-density SNP datasets in eight animal species (cat, cattle, dog, goat, horse, pig, sheep and water buffalo; 442 different populations) and make these results publicly available.

RESULTS

The results include an overview of ROH islands per population and a comparison of the incidence of these ROH islands among populations from the same species, which can assist researchers when studying other (livestock) populations or when looking for similar signatures of selection. We were able to confirm many known ROH islands, for example signatures of selection for the myostatin (MSTN) gene in sheep and horses. However, our results also included multiple other ROH islands, which are common to many populations and not identified to date (e.g. on chromosomes D4 and E2 in cats and on chromosome 6 in sheep).

CONCLUSIONS

We are confident that our repository of ROH islands is a valuable reference for future studies. The discovered ROH island regions represent a unique starting point for new studies or can be used as a reference for future studies. Furthermore, we encourage authors to add their population-specific ROH findings to our repository.

Genomic Characterization of the Istrian Shorthaired Hound

Istrian shorthaired hound is an old indigenous Croatian dog breed with historical traces of its origin, which date back to the 14th century. Due to its intelligence and great hunting abilities, it is considered an excellent hunting dog. Despite its ancient origin, there is no data on genetic diversity, population structure, and degree of inbreeding that could be used for advanced management and conservation of this breed. Our study aimed to provide a high-resolution population structure of the Istrian shorthaired hound using a 220K HD SNP array, to compare the obtained data with the genealogical records and to place the breed in a broader context of world dog populations. Relatively high population size and low inbreeding coefficient estimated from genealogical data indicate a preserved genetic diversity in this breed. The principle component analysis, the NeighborNet network, and TreeMix were used to determine the genetic relationship between the Istrian shorthaired hound and other breeds. The Istrian shorthaired hound was found to be genetically related to Italian hunting dogs sharing the same branch with the Segugio Italiano a Pelo Raso and Segugio Italiano a Pelo Forte. The ADMIXTURE analysis indicated that the Istrian shorthaired hound could be involved in the development of some other hunting dog breeds. The estimated effective population size (Ne) based on SNP data was similar to Ne calculated from genealogical data indicating the absence of bottlenecks and well-balanced use of breeding animals. The low genomic inbreeding coefficient, together with the higher number of short runs of homozygosity, observed in the Istrian shorthaired hound, confirms the ancient origin of the breed based on historical documents. The analysis of selective sweeps identified genomic regions with the strongest selection signals in the vicinity of the genes associated with cognitive performance and behavior. Genome analysis proved to be a useful tool for estimating population parameters and can be implemented in the conservation plan for this indigenous breed.

Genetic variations and dog breed identification using inter-simple sequence repeat markers coupled with high resolution melting analysis

The identification of differing physical characteristics of dogs is an uncomplicated and straightforward way to categorize dog breeds. However, many dog owners and veterinarians still struggle to distinguish between pure breed and mixed variations in certain breeds of dogs. Presently, the absence of the tools and methods needed to confirm a pure breed dog is a significant problem since the only method available to validate pure or mongrel breeds is the official pedigree system. Inter-simple sequence repeat markers have been successfully used to assess genetic variations and differentiations. Notably, inter-simple sequence repeat markers coupled with high resolution melting analysis were effectively used for the breed identification of 43 breeds of dogs (total 463 dogs). The 10 primers chosen for analysis resulted in a range of 31-78.6% of breed discrimination when using one primer, while a combination of two primers was able to successfully discriminate between all of the 43 dog breeds (100%). Shannon's index information (I = 2.586 ± 0.034) and expected heterozygosity (H e  = 0.908 ± 0.003) indicated a high level of genetic diversity among breeds. The fixation index (F st ) revealed a value of 10.4%, demonstrating that there was a high level of genetic subdivision between populations. This study showed that inter-simple sequence repeat marker analysis was effective in demonstrating high genetic diversity among varying breeds of dogs, while a combination of Inter-simple sequence repeat marker analysis and high resolution melting analysis could provide an optional technique for researchers to effectively identify breeds through genetic variations.

Origins and genetic legacy of prehistoric dogs

Dogs were the first domestic animal, but little is known about their population history and to what extent it was linked to humans. We sequenced 27 ancient dog genomes and found that all dogs share a common ancestry distinct from present-day wolves, with limited gene flow from wolves since domestication but substantial dog-to-wolf gene flow. By 11,000 years ago, at least five major ancestry lineages had diversified, demonstrating a deep genetic history of dogs during the Paleolithic. Coanalysis with human genomes reveals aspects of dog population history that mirror humans, including Levant-related ancestry in Africa and early agricultural Europe. Other aspects differ, including the impacts of steppe pastoralist expansions in West and East Eurasia and a near-complete turnover of Neolithic European dog ancestry.

What the dingo says about dog domestication

Worldwide, dogs (Canis familiaris) are certainly the most common domesticate (900 million according to the World Atlas) and are sometimes used as a proxy for human presence. Dogs were the first and therefore arguably most important species ever to be domesticated. It is widely accepted that the domestic dog is a descendent of Pleistocene gray wolves (Canis lupus), possibly of a population now extinct. How can an extant canid, the dingo (Canis dingo or Canis familiaris), whose status as a species and as a domesticate is controversial, improve our understanding of the ancient process of domesticating the dog? Here I review anatomical, behavioral, biogeographic, and molecular evidence on the appropriate status of dingoes in a historical context. Dingoes are now the major apex predator in Australia aside from humans. Different sources of evidence have suggested different times of arrival in Greater Australia for humans and canids and different degrees of intimacy or domestication between humans and canids. Just as domestic dogs are often accorded near‐human status, dingoes have special relationships with human families, but reproductively and behaviorally they remain independent. In sum, traits of the dingo reflect its lupine ancestry, a certain degree of accommodation to human company, and unique adaptations to the demands of its habitat. Emphasizing that domestication is a long‐term process, not an event, helps clarify the ambiguous status of dingoes.

New Guinea highland wild dogs are the original New Guinea singing dogs

New Guinea singing dogs (NGSD) are identifiable by their namesake vocalizations, which are unlike any other canid population. Their novel behaviors and potential singular origin during dog domestication make them an attractive, but elusive, subject for evolutionary and conservation study. Although once plentiful on the island of New Guinea (NG), they were presumed to currently exist only in captivity. This conclusion was based on the lack of sightings in the lowlands of the island and the concurrent expansion of European- and Asian-derived dogs. We have analyzed the first nuclear genomes from a canid population discovered during a recent expedition to the highlands of NG. The extreme altitude (>4,000 m) of the highland wild dogs' (HWD) observed range and confirmed vocalizations indicate their potential to be a wild NGSD population. Comparison of single-nucleotide polymorphism genotypes shows strong similarity between HWD and the homogeneous captive NGSD, with the HWD showing significantly higher genetic diversity. Admixture analyses and estimation of shared haplotypes with phylogenetically diverse populations also indicates the HWD is a novel population within the distinct evolutionary lineage of Oceanic canids. Taken together, these data indicate the HWD possesses a distinct potential to aid in the conservation of NGSD both in the wild and under human care.

Humans Dominate the Social Interaction Networks of Urban Free-Ranging Dogs in India

Research on human-animal interaction has skyrocketed in the last decade. Rapid urbanization has led scientists to investigate its impact on several species living in the vicinity of humans. Domesticated dogs (Canis lupus familiaris) are one such species that interact with humans and are also called man's best friend. However, when it comes to the free-ranging population of dogs, interactions become quite complicated. Unfortunately, studies regarding free-ranging dog-human interactions are limited even though the majority of the world's dog population is free-ranging. In this study, we observed twelve groups of free-ranging dogs in their natural habitat, the streets. We quantified their interactions at the intra (dog-dog) and interspecific (dog-human) levels. The study areas were divided into two zones, namely - intermediate and high flux, based on human activity or movement. Social network analysis revealed higher instances of interspecific than intraspecific interactions, irrespective of the human flux zones. Humans, in significantly higher occasions, initiated both positive and negative behaviors in comparison to dogs. Our findings conclude that humans are a crucial part of the interaction network of Indian free-ranging dogs.

The first evidence for Late Pleistocene dogs in Italy

The identification of the earliest dogs is challenging because of the absence and/or mosaic pattern of morphological diagnostic features in the initial phases of the domestication process. Furthermore, the natural occurrence of some of these characters in Late Pleistocene wolf populations and the time it took from the onset of traits related to domestication to their prevalence remain indefinite. For these reasons, the spatiotemporal context of the early domestication of dogs is hotly debated. Our combined molecular and morphological analyses of fossil canid remains from the sites of Grotta Paglicci and Grotta Romanelli, in southern Italy, attest of the presence of dogs at least 14,000 calibrated years before present. This unambiguously documents one of the earliest occurrence of domesticates in the Upper Palaeolithic of Europe and in the Mediterranean. The genetic affinity between the Palaeolithic dogs from southern Italy and contemporaneous ones found in Germany also suggest that these animals were an important common adjunct during the Late Glacial, when strong cultural diversification occurred between the Mediterranean world and European areas north of the Alps. Additionally, aDNA analyses indicate that this Upper Palaeolithic dog lineage from Italy may have contributed to the genetic diversity of living dogs.

A scan for genes associated with cancer mortality and longevity in pedigree dog breeds

Selective breeding of the domestic dog (Canis lupus familiaris) rigidly retains desirable features, and could inadvertently fix disease-causing variants within a breed. We combine phenotypic data from > 72,000 dogs with a large genotypic dataset to search for genes associated with cancer mortality and longevity in pedigree dog breeds. We validated previous findings that breeds with higher average body weight have higher cancer mortality rates and lower life expectancy. We identified a significant positive correlation between life span and cancer mortality residuals corrected for body weight, implying that long-lived breeds die more frequently from cancer compared to short-lived breeds. We replicated a number of known genetic associations with body weight (IGF1, GHR, CD36, SMAD2 and IGF2BP2). Subsequently, we identified five genetic variants in known cancer-related genes (located within SIPA1, ADCY7 and ARNT2) that could be associated with cancer mortality residuals corrected for confounding factors. One putative genetic variant was marginally significantly associated with longevity residuals that had been corrected for the effects of body weight; this genetic variant is located within PRDX1, a peroxiredoxin that belongs to an emerging class of pro-longevity associated genes. This research should be considered as an exploratory analysis to uncover associations between genes and longevity/cancer mortality.

Arctic-adapted dogs emerged at the Pleistocene-Holocene transition

Although sled dogs are one of the most specialized groups of dogs, their origin and evolution has received much less attention than many other dog groups. We applied a genomic approach to investigate their spatiotemporal emergence by sequencing the genomes of 10 modern Greenland sled dogs, an ~9500-year-old Siberian dog associated with archaeological evidence for sled technology, and an ~33,000-year-old Siberian wolf. We found noteworthy genetic similarity between the ancient dog and modern sled dogs. We detected gene flow from Pleistocene Siberian wolves, but not modern American wolves, to present-day sled dogs. The results indicate that the major ancestry of modern sled dogs traces back to Siberia, where sled dog-specific haplotypes of genes that potentially relate to Arctic adaptation were established by 9500 years ago.