Alberto Carmagnini

Archaeological evidence suggests that dogs diverged from wolves during the Palaeolithic, more than 15,000 years ago ^1–7 . The earliest unequivocal genetic evidence, however, is associated with dog remains from Mesolithic archaeological contexts approximately 10,900 years ago ^8,9 . Here we generate both nuclear and mitochondrial genomes from canid remains at Pınarbaşı in Türkiye (15,800 years ago) ¹⁰ and Gough’s Cave in the UK (14,300 years ago) ¹¹ , as well as from dogs excavated from two Mesolithic sites in Serbia (Padina between 11,500–7,900 years ago and Vlasac 8,900 years ago) ^12,13 . Our analyses indicate that a genetically homogeneous dog population was already widely distributed across Europe and Anatolia during the Late Upper Palaeolithic (by at least 14,300 years ago). This finding suggests that dogs were exchanged among genetically and culturally distinct western Eurasian Late Palaeolithic human populations, namely the Magdalenian, Epigravettian and Anatolian hunter-gatherers ^10,14–16 . Last, we identify a major influx of eastern Eurasian dog ancestry during the Mesolithic, concomitant with the movement of eastern hunter-gatherer populations into Europe ¹⁴ , which led to the establishment of the primary ancestry characteristics that define European dog populations today.

Many contemporary breed dogs display reduced genomic health compared to mixed-breed dogs, including reduced heterozygosity and increased genetic load, likely due to strong directed breeding. Lack of historical genomes, however, has made it difficult to disentangle the timing and drivers of these declines given complex and breed-specific demographic histories, artificial selection, and crossbreeding. Here, we sequenced genomes of nine 20th-century museum specimens (1906–1993) of pedigree German Shepherd Dogs (GSDs) to directly assess the consequences of contemporary breeding practices on genomic diversity and health over time. The GSD breed offers an excellent case study, given the breed’s fluctuations in global popularity, differing selective regimes, and the GSD’s use in the establishment of other breeds, including wolfdogs. Genome-wide heterozygosity showed significant reductions after the Second World War (WWII), coincident with an increase in both the frequency of runs of homozygosity and load. We also detected repeated population bottlenecks linked to the use of popular sires throughout the 20th century. Finally, although hybridization with wolves has led to genome-wide increases in heterozygosity in wolfdog breeds derived from the GSD, nonadmixed ancestry blocks (dog or wolf) were severely depleted in diversity due to the limited number of founders involved in their establishment. Combined, our results indicate that declines in the genomic health of GSDs and related breeds occurred not at the onset of breed formation but throughout the last century, as a result of population bottlenecks associated with WWII and the repeated use of popular sires.

The multi-millennia-long history between dogs and humans has placed them at the forefront of archaeological and genomic research. Despite ongoing efforts including the analysis of ancient dog and wolf genomes, many questions remain regarding the evolutionary processes that led to the diversity of breeds today. Although ancient genome sequences provide valuable information about these processes, their utility is hindered by low depths of coverage and postmortem damage, which inhibits confident genotype calling. In the present study, we assess how genotype imputation of ancient dog and wolf genomes, using a large reference panel, can increase the amount of information provided by ancient datasets. We evaluated imputation accuracy by down-sampling high-coverage dog and wolf genomes to 0.05 to 2× coverage and compared concordance between imputed and high-coverage genotypes. We measured the impact of imputation on principal component analyses and runs of homozygosity (ROH). Our findings show high (R ² > 0.9) imputation accuracy for dogs with coverage as low as 0.5× and for wolves as low as 1.0×. We then imputed a dataset of 90 ancient dog and wolf genomes to assess changes in inbreeding during the last 10,000 y of dog evolution. Ancient dog and wolf populations generally exhibit lower inbreeding levels than present-day individuals. Regions with low ROH density maintained across ancient and present-day dogs were significantly associated with genes related to immunity and chemosensory receptors. Our study indicates that imputing ancient canine genomes is a viable strategy that allows for the use of analytical methods previously limited to high-quality genetic data.

As the first domestic species, dogs likely dispersed with different cultural groups during the Late Pleistocene and Holocene. To test this hypothesis, we analyzed 73 ancient dog genomes, including 17 newly sequenced individuals sampled from East Asia to the West Eurasian Steppe spanning nearly 10,000 years. Our results indicate correlations between the ancestry of dogs and specific ancient human populations from eastern Europe to Eastern Siberia, including Ancient Paleo-Siberians, Eastern hunter-gatherers, East Asians, and Steppe pastoralists. We also identify multiple shifts in the ancestry of dogs that coincide with specific dispersals of hunter-gatherers, farmers, and pastoralists. Combined, our results reveal the long-term and integral role that dogs played in a multitude of human societies.

Island populations of large vertebrates have experienced higher extinction rates than mainland populations over long timescales due to demographic stochasticity, genetic drift, and inbreeding. While being more susceptible to extinction and as such potentially targeted for conservation interventions such as genetic rescue, small-island populations can experience relatively less anthropogenic habitat degradation than those on larger islands. Here, we determine the consequences and conservation implications of long-term isolation and recent human activities on genetic diversity of island populations of two forest-dependent mammals endemic to the Wallacea archipelago: the anoa ( Bubalus spp.) and babirusa ( Babyrousa spp.). Using genomic analyses and habitat suitability models, we show that, compared to closely related species, populations on mainland Sulawesi exhibit low heterozygosity, high inbreeding, a high proportion of deleterious alleles, and experience a high rate of anthropogenic disturbance. In contrast, populations on smaller islands occupy higher-quality habitats, possess fewer deleterious mutations despite exhibiting lower heterozygosity and higher inbreeding. Site frequency spectra indicate that these patterns reflect stronger, long-term purging in smaller-island populations. Our results thus suggest that conservation efforts should focus on protecting small-island high-quality habitats and avoiding translocations from mainland populations. This study highlights the crucial role of small offshore islands for the long-term survival of Wallacea’s iconic and indigenous mammals in the face of development on the mainland.

Island populations of large vertebrates have experienced higher extinction rates than mainland populations over long timescales due to demographic stochasticity, genetic drift and inbreeding. Conversely, small island populations often experience relatively less anthropogenic habitat degradation than populations on larger islands, making them potential targets for conservation interventions such as genetic rescue to improve their overall genetic diversity. Here we determine the consequences and conservation implications of long-term isolation and recent human activities on genetic diversity of island populations of two forest-dependent mammals endemic to the Wallacea archipelago: the anoa ( Bubalus spp.) and babirusa ( Babyrousa spp.). Using genomic analyses and habitat suitability models, we show that, compared to closely related species, populations on mainland Sulawesi exhibit low heterozygosity, high inbreeding, and a high proportion of deleterious alleles. In contrast, populations on smaller islands possess fewer deleterious mutations despite exhibiting lower heterozygosity and higher inbreeding. Site frequency spectra indicate that these patterns reflect stronger, long-term purging in smaller island populations. Our results thus suggest that conservation efforts should focus on protecting small island habitats and avoiding translocations from mainland populations. This study highlights the crucial role of small offshore islands for the long-term survival of Wallacea’s iconic and indigenous mammals in the face of development on the mainland. Significance statement: Within tropical archipelagos, such as the Wallacea biodiversity hotspot, larger islands experience greater resource exploitation compared to smaller ones, highlighting the potential of smaller islands as refuges for conservation. To investigate the genetic health of populations on small islands, we used genomic, occurrence, and environmental data from a system of replicated populations of anoa and babirusa across islands of varying sizes. In contrast to larger islands like Sulawesi, our results demonstrate that smaller offshore islands not only provide higher-quality habitats but also support populations that have efficiently purged harmful mutations. Thus, despite their known vulnerability over geological time-frames, small island populations can provide long term insurance against human-driven extinction and conservation efforts should prioritise habitat management over translocations.

The multi-millenia long history between dogs and humans has placed them at the forefront of archeological and genomic research. Despite ongoing efforts including the analysis of ancient dog and wolf genomes, many questions remain regarding their geographic and temporal origins, and the microevolutionary processes that led to the diversity of breeds today. Although ancient genomes provide valuable information, their use is hindered by low depth of coverage and post-mortem damage, which inhibits confident genotype calling. In the present study, we assess how genotype imputation of ancient dog and wolf genomes, utilising a large reference panel, can improve the resolution provided by ancient datasets. Imputation accuracy was evaluated by down-sampling high coverage dog and wolf genomes to 0.05-2x coverage and comparing concordance between imputed and high coverage genotypes. We measured the impact of imputation on principal component analyses and runs of homozygosity. Our findings show high (R ² >0.9) imputation accuracy for dogs with coverage as low as 0.5x and for wolves as low as 1.0x. We then imputed a dataset of 90 ancient dog and wolf genomes, to assess changes in inbreeding during the last 10,000 years of dog evolution. Ancient dog and wolf populations generally exhibited lower inbreeding levels than present-day individuals. Interestingly, regions with low ROH density maintained across ancient and present-day samples were significantly associated with genes related to olfaction and immune response. Our study indicates that imputing ancient canine genomes is a viable strategy that allows for the use of analytical methods previously limited to high-quality genetic data.

Ancestral Coast Salish societies in the Pacific Northwest kept long-haired “woolly dogs” that were bred and cared for over millennia. However, the dog wool–weaving tradition declined during the 19th century, and the population was lost. In this study, we analyzed genomic and isotopic data from a preserved woolly dog pelt from “Mutton,” collected in 1859. Mutton is the only known example of an Indigenous North American dog with dominant precolonial ancestry postdating the onset of settler colonialism. We identified candidate genetic variants potentially linked with their distinct woolly phenotype. We integrated these data with interviews from Coast Salish Elders, Knowledge Keepers, and weavers about shared traditional knowledge and memories surrounding woolly dogs, their importance within Coast Salish societies, and how colonial policies led directly to their disappearance.

Identification of specific species in metagenomic samples is critical for several key applications, yet many tools available require large computational power and are often prone to false positive identifications. Here we describe High-AccuracY and Scalable Taxonomic Assignment of MetagenomiC data (HAYSTAC), which can estimate the probability that a specific taxon is present in a metagenome. HAYSTAC provides a user-friendly tool to construct databases, based on publicly available genomes, that are used for competitive read mapping. It then uses a novel Bayesian framework to infer the abundance and statistical support for each species identification and provide per-read species classification. Unlike other methods, HAYSTAC is specifically designed to efficiently handle both ancient and modern DNA data, as well as incomplete reference databases, making it possible to run highly accurate hypothesis-driven analyses (i.e., assessing the presence of a specific species) on variably sized reference databases while dramatically improving processing speeds. We tested the performance and accuracy of HAYSTAC using simulated Illumina libraries, both with and without ancient DNA damage, and compared the results to other currently available methods (i.e., Kraken2/Bracken, KrakenUniq, MALT/HOPS, and Sigma). HAYSTAC identified fewer false positives than both Kraken2/Bracken, KrakenUniq and MALT in all simulations, and fewer than Sigma in simulations of ancient data. It uses less memory than Kraken2/Bracken, KrakenUniq as well as MALT both during database construction and sample analysis. Lastly, we used HAYSTAC to search for specific pathogens in two published ancient metagenomic datasets, demonstrating how it can be applied to empirical datasets. HAYSTAC is available fromhttps://github.com/antonisdim/HAYSTAC.

Significance: The Siberian Arctic has witnessed numerous societal changes since the first known appearance of dogs in the region ∼10,000 years ago. These changes include the introduction of ironworking ∼2,000 years ago and the emergence of reindeer pastoralism ∼800 years ago. The analysis of 49 ancient dog genomes reveals that the ancestry of Arctic Siberia dogs shifted over the last 2,000 years due to an influx of dogs from the Eurasian Steppe and Europe. Combined with genomic data from humans and archaeological evidence, our results suggest that though the ancestry of human populations in Arctic Siberia did not change over this period, people there participated in trade with distant communities that involved both dogs and material culture.