Publications by authors named "Love Dalen"

Large-scale DNA screening of palaeontological and archaeological collections remains a limiting and costly factor for ancient DNA studies. Several DNA extraction protocols are routinely used in ancient DNA laboratories and have even been automated on robotic platforms. Robots offer a solution for high-throughput screening but the costs, as well as necessity for trained technicians and engineers, can be prohibitive for some laboratories.

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Inbreeding increases genome homozygosity within populations, which can exacerbate inbreeding depression by exposing homozygous deleterious alleles that are responsible for declines in fitness traits. In small populations, genetic purging that occurs under pressure of natural selection acts as an opposing force, contributing to a reduction of deleterious alleles. Both inbreeding and genetic purging are paramount in the field of conservation genomics.

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Following glacial retreat after the last ice age, brown bears (Ursus arctos) recolonised Scandinavia. Previous research based on mitochondrial markers suggests that bears recolonised from both the north and the south, with a contact zone in central Scandinavia. More recently, the Scandinavian brown bear was subjected to a strong population decline with only ca.

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Inbreeding depression has been documented in various fitness traits in a wide range of species and taxa, however, the mutational basis is not yet well understood. We investigate how putatively deleterious variation influences fitness and is shaped by individual ancestry by re-sequencing complete genomes of 37 individuals in a natural arctic fox (Vulpes lagopus) population subjected to both inbreeding depression and genetic rescue. We find that individuals with high proportion of homozygous loss of function genotypes (LoFs), which are predicted to exert a strong effect on fitness, generally have lower lifetime reproductive success and live shorter lives compared with individuals with lower proportion of LoFs.

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Article Synopsis
  • A genomic database encompassing all eukaryotic species on Earth is crucial for scientific advancements, yet most species lack genomic data.
  • The Earth BioGenome Project (EBP) was initiated in 2018 by global scientists to compile high-quality reference genomes for approximately 1.5 million recognized eukaryotic species.
  • The European Reference Genome Atlas (ERGA) launched a Pilot Project to create a decentralized model for reference genome production by testing it on 98 species, providing valuable insights into scalability, equity, and inclusiveness for genomic projects.
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Analyses of ancient DNA typically involve sequencing the surviving short oligonucleotides and aligning to genome assemblies from related, modern species. Here, we report that skin from a female woolly mammoth (†Mammuthus primigenius) that died 52,000 years ago retained its ancient genome architecture. We use PaleoHi-C to map chromatin contacts and assemble its genome, yielding 28 chromosome-length scaffolds.

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Article Synopsis
  • - The alignment of sequencing reads is crucial for studying ancient genomes, but challenges like reference bias and spurious mappings can lead to inaccurate results, especially as new lab techniques produce larger datasets.
  • - The study introduces AMBER, a new bioinformatics tool designed to evaluate ancient DNA mapping quality, providing insights into reference bias and mismatch rates across various read lengths.
  • - AMBER allows researchers to analyze factors affecting mapping accuracy, showing that the choice of mapping algorithms and quality thresholds significantly influences results, which can help improve alignment strategies for ancient DNA.
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A number of species have recently recovered from near-extinction. Although these species have avoided the immediate extinction threat, their long-term viability remains precarious due to the potential genetic consequences of population declines, which are poorly understood on a timescale beyond a few generations. Woolly mammoths (Mammuthus primigenius) became isolated on Wrangel Island around 10,000 years ago and persisted for over 200 generations before becoming extinct around 4,000 years ago.

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Hybridization can result in the transfer of adaptive genetic material from one species to another, known as adaptive introgression. Bottlenecked (and hence genetically depleted) species are expected to be particularly receptive to adaptive introgression, since introgression can introduce new or previously lost adaptive genetic variation. The Alpine ibex (Capra ibex), which recently recovered from near extinction, is known to hybridize with the domestic goat (Capra aegagrus hircus), and signals of introgression previously found at the major histocompatibility complex were suggested to potentially be adaptive.

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Interest continues to grow in Arctic megafaunal ecological engineering, but, since the mass extinction of megafauna ~ 12-15 ka, key physiographic variables and available forage continue to change. Here we sought to assess the extent to which contemporary Arctic ecosystems are conducive to the rewilding of megaherbivores, using a woolly mammoth (M. primigenius) proxy as a model species.

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Low genomic diversity is generally indicative of small population size and is considered detrimental by decreasing long-term adaptability. Moreover, small population size may promote gene flow with congeners and outbreeding depression. Here, we examine the connection between habitat availability, effective population size (N), and extinction by generating a 40× nuclear genome from the extinct blue antelope (Hippotragus leucophaeus).

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Article Synopsis
  • Genomic techniques can significantly enhance conservation efforts by identifying threats to various species and populations, as well as assisting in biodiversity restoration.
  • The text outlines two main areas of genomic research in conservation: vulnerability genomics, which focuses on assessing risks, and restoration genomics, which is aimed at recovery efforts.
  • Current applications of these genomic approaches are examined, along with key questions that remain unanswered and the future possibilities they hold for enhancing conservation strategies.
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Climate warming at the end of the last glacial period had profound effects on the distribution of cold-adapted species. As their range shifted towards northern latitudes, they were able to colonise previously glaciated areas, including remote Arctic islands. However, there is still uncertainty about the routes and timing of colonisation.

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Genetic diversity is lost in small and isolated populations, affecting many globally declining species. Interspecific admixture events can increase genetic variation in the recipient species' gene pool, but empirical examples of species-wide restoration of genetic diversity by admixture are lacking. Here we present multi-fold coverage genomic data from three ancient Iberian lynx (Lynx pardinus) approximately 2,000-4,000 years old and show a continuous or recurrent process of interspecies admixture with the Eurasian lynx (Lynx lynx) that increased modern Iberian lynx genetic diversity above that occurring millennia ago despite its recent demographic decline.

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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.

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Article Synopsis
  • - Genomic studies on endangered species help us understand how they evolve and survive despite population declines and bottlenecks, offering clues on avoiding extinction.
  • - The researchers focused on the muskox, which nearly went extinct after the last Ice Age but is now thriving, examining 108 whole genomes from current populations and an ancient specimen.
  • - They found that past climate changes influenced muskox demographics, with the white-faced subspecies showing extremely low genetic variation without signs of inbreeding depression, suggesting that gradual population declines might have removed harmful mutations.
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Analysis of microbial data from archaeological samples is a growing field with great potential for understanding ancient environments, lifestyles, and diseases. However, high error rates have been a challenge in ancient metagenomics, and the availability of computational frameworks that meet the demands of the field is limited. Here, we propose aMeta, an accurate metagenomic profiling workflow for ancient DNA designed to minimize the amount of false discoveries and computer memory requirements.

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Ungulate species have experienced severe declines over the past centuries through overharvesting and habitat loss. Even if many game species have recovered thanks to strict hunting regulation, the genome-wide impacts of overharvesting are still unclear. Here, we examine the temporal and geographical differences in genome-wide diversity in moose (Alces alces) over its whole range in Sweden by sequencing 87 modern and historical genomes.

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Although most ancient DNA studies have focused on the last 50,000 years, paleogenomic approaches can now reach into the early Pleistocene, an epoch of repeated environmental changes that shaped present-day biodiversity. Emerging deep-time genomic transects, including from DNA preserved in sediments, will enable inference of adaptive evolution, discovery of unrecognized species, and exploration of how glaciations, volcanism, and paleomagnetic reversals shaped demography and community composition. In this Review, we explore the state-of-the-art in paleogenomics and discuss key challenges, including technical limitations, evolutionary divergence and associated biases, and the need for more precise dating of remains and sediments.

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Anthropogenic reintroduction can supplement natural recolonization in reestablishing a species' distribution and abundance. However, both reintroductions and recolonizations can give rise to founder effects that reduce genetic diversity and increase inbreeding, potentially causing the accumulation of genetic load and reduced fitness. Most current populations of the endemic high-arctic Svalbard reindeer () originate from recent reintroductions or recolonizations following regional extirpations due to past overharvesting.

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Typically much smaller in number than their mainland counterparts, island populations are ideal systems to investigate genetic threats to small populations. The Svalbard reindeer () is an endemic subspecies that colonized the Svalbard archipelago ca. 6,000-8,000 years ago and now shows numerous physiological and morphological adaptations to its arctic habitat.

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Article Synopsis
  • The black rhinoceros is critically endangered, with its numbers drastically reduced due to hunting and poaching, particularly in the late 20th century.
  • Researchers conducted genomic studies on 63 historical black rhinoceros specimens to identify six major historic populations and their subpopulations, revealing significant genetic structure influenced by geographic barriers.
  • Findings from this genetic analysis provide insights for developing urgent management strategies aimed at conserving the remaining diversity of black rhinoceros populations.
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Paleogenomics continues to yield valuable insights into the evolution, population dynamics, and ecology of our ancestors and other extinct species. However, DNA sequencing cannot reveal tissue-specific gene expression, cellular identity, or gene regulation, which are only attainable at the transcriptional level. Pioneering studies have shown that useful RNA can be extracted from ancient specimens preserved in permafrost and historical skins from extant canids, but no attempts have been made so far on extinct species.

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