​Comparative genomics of Balto, a famous historic dog, captures lost diversity of 1920s sled dogs

An Evolutionary Perspective on Dog Behavioral Genetics

Dogs have played an outsized role in the field of behavioral genetics since its earliest days. Their unique evolutionary history and ubiquity in the modern world make them a potentially powerful model system for discovering how genetic changes lead to changes in behavior. Genomic technology has supercharged this potential by enabling scientists to sequence the DNA of thousands of dogs and test for correlations with behavioral traits. However, fractures in the early history of animal behavior between biological and psychological subfields may be impeding progress. In addition, canine behavioral genetics has included almost exclusively dogs from modern breeds, who represent just a small fraction of all dog diversity. By expanding the scope of dog behavior studies, and incorporating an evolutionary perspective on canine behavioral genetics, we can move beyond associations to understanding the complex interactions between genes and environment that lead to dog behavior.

Comparative Population Genomics of Arctic Sled Dogs Reveals a Deep and Complex History

Recent evidence demonstrates genomic and morphological continuity in the Arctic ancestral lineage of dogs. Here, we use the Siberian Husky to investigate the genomic legacy of the northeast Eurasian Arctic lineage and model the deep population history using genome-wide single nucleotide polymorphisms. Utilizing ancient dog-calibrated molecular clocks, we found that at least two distinct lineages of Arctic dogs existed in ancient Eurasia at the end of the Pleistocene. This pushes back the origin of sled dogs in the northeast Siberian Arctic with humans likely intentionally selecting dogs to perform different functions and keeping breeding populations that overlap in time and space relatively reproductively isolated. In modern Siberian Huskies, we found significant population structure based on how they are used by humans, recent European breed introgression in about half of the dogs that participate in races, moderate levels of inbreeding, and fewer potentially harmful variants in populations under strong selection for form and function (show, sled show, and racing populations of Siberian Huskies). As the struggle to preserve unique evolutionary lineages while maintaining genetic health intensifies across pedigreed dogs, understanding the genomic history to guide policies and best practices for breed management is crucial to sustain these ancient lineages and their unique evolutionary identity.

Assessing Assembly Errors in Immunoglobulin Loci: A Comprehensive Evaluation of Long-read Genome Assemblies Across Vertebrates

Long-read sequencing technologies have revolutionized genome assembly producing near-complete chromosome assemblies for numerous organisms, which are invaluable to research in many fields. However, regions with complex repetitive structure continue to represent a challenge for genome assembly algorithms, particularly in areas with high heterozygosity. Robust and comprehensive solutions for the assessment of assembly accuracy and completeness in these regions do not exist. In this study we focus on the assembly of biomedically important antibody-encoding immunoglobulin (IG) loci, which are characterized by complex duplications and repeat structures. High-quality full-length assemblies for these loci are critical for resolving haplotype-level annotations of IG genes, without which, functional and evolutionary studies of antibody immunity across vertebrates are not tractable. To address these challenges, we developed a pipeline, "CloseRead", that generates multiple assembly verification metrics for analysis and visualization. These metrics expand upon those of existing quality assessment tools and specifically target complex and highly heterozygous regions. Using CloseRead, we systematically assessed the accuracy and completeness of IG loci in publicly available assemblies of 74 vertebrate species, identifying problematic regions. We also demonstrated that inspecting assembly graphs for problematic regions can both identify the root cause of assembly errors and illuminate solutions for improving erroneous assemblies. For a subset of species, we were able to correct assembly errors through targeted reassembly. Together, our analysis demonstrated the utility of assembly assessment in improving the completeness and accuracy of IG loci across species.

Improving data archiving practices in ancient genomics

Ancient DNA is producing a rich record of past genetic diversity in humans and other species. However, unless the primary data is appropriately archived, its long-term value will not be fully realised. I surveyed publicly archived data from 42 recent ancient genomics studies. Half of the studies archived incomplete datasets, preventing accurate replication and representing a loss of data of potential future use. No studies met all criteria that could be considered best practice. Based on these results, I make six recommendations for data producers: (1) archive all sequencing reads, not just those that aligned to a reference genome, (2) archive read alignments too, but as secondary analysis files, (3) provide correct experiment metadata on samples, libraries and sequencing runs, (4) provide informative sample metadata, (5) archive data from low-coverage and negative experiments, and (6) document archiving choices in papers, and peer review these. Given the reliance on destructive sampling of finite material, ancient genomics studies have a particularly strong responsibility to ensure the longevity and reusability of generated data.

Balto and Togo during the cold winter of Alaska (1925): the two canine heroes in the fight against diphtheria

In recent years, diphtheria has re-emerged in areas with inadequate vaccination coverage, and Europe has not been spared with several cases among migrants. Diphtheria is a potentially fatal infection caused mainly by toxigenic strains of Corynebacterium diphtheriae. Due to the high mortality rate, especially among young children, the fight against diphtheria is considered one of the first conquests of immunization. In the history of medicine, there is a unique case of an unconventional response to a diphtheria outbreak in which sled dogs were used to overcome the supply difficulties of diphtheria antitoxin. The mass media followed the medical response to the outbreak and raised audience awareness of public health issues. The facts of Nome, Alaska, in 1925 can serve as a catalyst to rethink conventional responses to diphtheria outbreaks in low-income countries today and promote mass media awareness of public health importance.

Analysis of the gut microbiome in sled dogs reveals glucosamine- and activity-related effects on gut microbial composition

The composition of the microbiome influences many aspects of physiology and health, and can be altered by environmental factors, including diet and activity. Glucosamine is a dietary supplement often administered to address arthritic symptoms in humans, dogs, and other mammals. To investigate how gut microbial composition varies with glucosamine supplementation, we performed 16S rRNA sequence analysis of fecal samples from 24 Alaskan and Inuit huskies and used mixed effects models to investigate associations with activity, age, and additional factors. Glucosamine ingestion, age, activity, sex, and diet were correlated with differences in alpha-diversity, with diversity decreasing in dogs consuming glucosamine. Beta-diversity analysis revealed clustering of dogs based on glucosamine supplementation status. Glucosamine supplementation and exercise-related activity were associated with greater inter-individual pairwise distances. At the family level, Lactobacillaceae and Anaerovoracaceae relative abundances were lower in supplemented dogs when activity was accounted for. At the genus level, Eubacterium [brachy], Sellimonus, Parvibacter, and an unclassified genus belonging to the same family as Parvibacter (Eggerthellaceae) all were lower in supplemented dogs, but only significantly so post-activity. Our findings suggest that glucosamine supplementation alters microbiome composition in sled dogs, particularly in the context of exercise-related activity.

Genomics expands the mammalverse

Diverse mammal genomes open a new portal to hidden aspects of evolutionary history.