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94 result(s) for "Frandsen, Peter"
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Mountain gorilla genomes reveal the impact of long-term population decline and inbreeding
Mountain gorillas are an endangered great ape subspecies and a prominent focus for conservation, yet we know little about their genomic diversity and evolutionary past. We sequenced whole genomes from multiple wild individuals and compared the genomes of all four Gorilla subspecies. We found that the two eastern subspecies have experienced a prolonged population decline over the past 100,000 years, resulting in very low genetic diversity and an increased overall burden of deleterious variation. A further recent decline in the mountain gorilla population has led to extensive inbreeding, such that individuals are typically homozygous at 34% of their sequence, leading to the purging of severely deleterious recessive mutations from the population. We discuss the causes of their decline and the consequences for their future survival.
Women’s preference for HPV self-sampling devices: a programme-embedded, large-scale paired comparative study within the cervical cancer screening programme in the Capital Region of Denmark
ObjectiveTo demonstrate women’s preferences for three human papillomavirus (HPV) self-sampling devices.DesignCross-sectional, programme-embedded paired comparative study with randomised sampling order within device pairs.SettingOrganised cervical cancer screening programme in the Capital Region of Denmark.Participants1760 women eligible for cervical cancer screening (April 2024 to May 2025), assigned to one of three groups: (1) Evalyn versus FLOQSwab (n=518), (2) Evalyn versus SensiGrip (n=657) and (3) FLOQSwab versus SensiGrip (n=585).Outcome measuresPrimary: device preference. Secondary: sampling-experience (self-reported). Data were assessed with χ² tests for preference, logistic regression for predictor analysis and Wilcoxon signed-rank equivalence test with two one-sided test procedures to assess sampling experience.ResultsOverall, 95.7% rated HPV self-sampling a positive experience and 87.3% preferred HPV self-sampling in future screening. SensiGrip was preferred significantly over FLOQSwab (p<0.001), with participants rating ease of use and sampling certainty higher for SensiGrip. No significant differences in preference were observed between Evalyn and either alternative device in the primary analysis (p>0.05) although Evalyn scored higher in sampling certainty. Sampling order influenced preference in Evalyn comparisons. Prior experience with self-sampling, screening history and subcohort membership did not significantly influence device preference.ConclusionsOverall, participants rated self-sampling a positive experience. SensiGrip was preferred over FLOQSwab, while Evalyn demonstrated comparable overall acceptability to both alternative devices in the primary implementation-focused analysis. These findings suggest that device replacement would be acceptable from a screening participation perspective, particularly a shift from FLOQSwab to SensiGrip.
Targeted conservation genetics of the endangered chimpanzee
Populations of the common chimpanzee (Pan troglodytes) are in an impending risk of going extinct in the wild as a consequence of damaging anthropogenic impact on their natural habitat and illegal pet and bushmeat trade. Conservation management programmes for the chimpanzee have been established outside their natural range (ex situ), and chimpanzees from these programmes could potentially be used to supplement future conservation initiatives in the wild (in situ). However, these programmes have often suffered from inadequate information about the geographical origin and subspecies ancestry of the founders. Here, we present a newly designed capture array with ~60,000 ancestry informative markers used to infer ancestry of individual chimpanzees in ex situ populations and determine geographical origin of confiscated sanctuary individuals. From a test panel of 167 chimpanzees with unknown origins or subspecies labels, we identify 90 suitable non-admixed individuals in the European Association of Zoos and Aquaria (EAZA) Ex situ Programme (EEP). Equally important, another 46 individuals have been identified with admixed subspecies ancestries, which therefore over time, should be naturally phased out of the breeding populations. With potential for future re-introduction to the wild, we determine the geographical origin of 31 individuals that were confiscated from the illegal trade and demonstrate the promises of using non-invasive sampling in future conservation action plans. Collectively, our genomic approach provides an exemplar for ex situ management of endangered species and offers an efficient tool in future in situ efforts to combat the illegal wildlife trade.
Genetics as a novel tool in mining impact assessment and biomonitoring of critically endangered western chimpanzees in the Nimba Mountains, Guinea
Western chimpanzees (Pan troglodytes verus) are Critically Endangered and Guinea is a key stronghold for this subspecies. However, Guinea is also rich in minerals with some of the highest‐grade iron‐ore deposits in the world. Specifically, the Nimba Mountains, home to western chimpanzees, is one of the sites under consideration for mining activities. To assess the impact of mining activities in the area, we used non‐invasive genetic sampling to estimate chimpanzee population size, sex ratio, community composition, and range boundaries on the western flank of the massif. The level of genetic diversity and affinity between communities was estimated and recommendations for future genetic censusing provided. Between 2003 and 2018, we collected 999 fecal samples of which 663 were analyzed using a panel of 26 microsatellites. We identified a minimum of 136 chimpanzees in four communities, with evidence of migratory events, a high level of shared ancestry and genetic diversity. We assessed sampling intensities and capture rates for each community. Saturation was reached in two communities with sampling between 3.2 and 4.3 times the estimated number of chimpanzees. Our findings highlight the utility of genetic censusing for temporal monitoring of ape abundance, as well as capturing migratory events and gauging genetic diversity and population viability over time. We recommend genetic sampling, combined with camera trapping, for use in future Environmental and Social Impact Assessments, as these methods can yield robust baselines for implementing the mitigation hierarchy, future biomonitoring and conservation management. We assessed the impact of mining activities in the Nimba Mountains of Guinea, West Africa. Genetic censusing yields key information on chimpanzee population structure and viability for mining impact assessment and biomonitoring.
Time Clustered Sampling Can Inflate the Inferred Substitution Rate in Foot-And-Mouth Disease Virus Analyses
With the emergence of analytical software for the inference of viral evolution, a number of studies have focused on estimating important parameters such as the substitution rate and the time to the most recent common ancestor (tMRCA) for rapidly evolving viruses. Coupled with an increasing abundance of sequence data sampled under widely different schemes, an effort to keep results consistent and comparable is needed. This study emphasizes commonly disregarded problems in the inference of evolutionary rates in viral sequence data when sampling is unevenly distributed on a temporal scale through a study of the foot-and-mouth (FMD) disease virus serotypes SAT 1 and SAT 2. Our study shows that clustered temporal sampling in phylogenetic analyses of FMD viruses will strongly bias the inferences of substitution rates and tMRCA because the inferred rates in such data sets reflect a rate closer to the mutation rate rather than the substitution rate. Estimating evolutionary parameters from viral sequences should be performed with due consideration of the differences in short-term and longer-term evolutionary processes occurring within sets of temporally sampled viruses, and studies should carefully consider how samples are combined.
Identification of constrained sequence elements across 239 primate genomes
Noncoding DNA is central to our understanding of human gene regulation and complex diseases 1 , 2 , and measuring the evolutionary sequence constraint can establish the functional relevance of putative regulatory elements in the human genome 3 – 9 . Identifying the genomic elements that have become constrained specifically in primates has been hampered by the faster evolution of noncoding DNA compared to protein-coding DNA 10 , the relatively short timescales separating primate species 11 , and the previously limited availability of whole-genome sequences 12 . Here we construct a whole-genome alignment of 239 species, representing nearly half of all extant species in the primate order. Using this resource, we identified human regulatory elements that are under selective constraint across primates and other mammals at a 5% false discovery rate. We detected 111,318 DNase I hypersensitivity sites and 267,410 transcription factor binding sites that are constrained specifically in primates but not across other placental mammals and validate their cis -regulatory effects on gene expression. These regulatory elements are enriched for human genetic variants that affect gene expression and complex traits and diseases. Our results highlight the important role of recent evolution in regulatory sequence elements differentiating primates, including humans, from other placental mammals. Whole-genome alignment of 239 primate species reveals noncoding regulatory elements that are under selective constraint in primates but not in other placental mammals, that are enriched for variants that affect human gene expression and complex traits in diseases.
Chimpanzee genomic diversity reveals ancient admixture with bonobos
Our closest living relatives, chimpanzees and bonobos, have a complex demographic history. We analyzed the high-coverage whole genomes of 75 wild-born chimpanzees and bonobos from 10 countries in Africa. We found that chimpanzee population substructure makes genetic information a good predictor of geographic origin at country and regional scales. Multiple lines of evidence suggest that gene flow occurred from bonobos into the ancestors of central and eastern chimpanzees between 200,000 and 550,000 years ago, probably with subsequent spread into Nigeria-Cameroon chimpanzees. Together with another, possibly more recent contact (after 200,000 years ago), bonobos contributed less than 1% to the central chimpanzee genomes. Admixture thus appears to have been widespread during hominid evolution.
More grist for the mill? Species delimitation in the genomic era and its implications for conservation
Species delimitation is one of the most contested areas in modern biology, with widespread disagreement about almost every aspect of the definition and implementation of the “species” label. While this debate is intellectually stimulating, it also has real implications for conservation, where its impacts on taxonomic inflation or inertia can mean that specific populations receive adequate conservation measures or are ignored. Recently, the rise of next generation sequencing and phylogenomics has revolutionised phylogenetic understanding of many organismal groups but has simultaneously highlighted the porosity of genomes in terms of admixture across previously delineated species barriers. The extraordinary power of genomic data is increasingly being used to delineate species, and several publications in this domain have recently attracted significant attention and criticism. Here we revisit the question of species delimitation, but from a genomic context. We ask how and whether the large amounts of data provided by genomic methods can resolve the longstanding discussion on the validity and application of phylogenetic and allied species concepts, and how some recent examples can inform this debate. We argue that conserving adaptive potential is a priority for conservation, and no single species concept currently does that adequately on its own. Genomic data holds the potential to add unprecedented detail, but frequently falls short of this potential.
Genetic diagnosis of trisomy 21 in chimpanzees (Pan troglodytes)
The most frequent chromosomal aneuploidy in humans, trisomy 21 (T21), has only been reported twice in the common chimpanzee (Pan troglodytes). In both cases, phenotypical traits were comparable to human T21 traits and were formally diagnosed through conventional techniques like chromosomal staining. Here, we present the first application of sequencing data as a diagnostic tool to compare chromosomal dosage imbalances in chimpanzees. By calculating the ratio of mapped reads on each chromosome between a case and a control, we observe a trisomic dosage imbalance on chromosome 21 in the case individual. While case numbers remain too low to be conclusive, evidence suggests that prevalence of T21 in chimpanzees could be lower than in humans. In future genetic testing of captive ape populations, the genetic diagnostic methods presented here will allow for a reliable and time-efficient assessment of the global prevalence of chromosomal dose imbalances in chimpanzees and other great apes.