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PubMed2026

Runs of Homozygosity Predict Inbreeding Depression Across Taxa: A Systematic Review and Meta-Analysis.

Measuring inbreeding via runs of homozygosity (ROH) captures realized autozygosity and can infer inbreeding timing through ROH length. A growing body of literature links the proportion of the genome in ROH (FROH) to fitness outcomes across taxa, yet systematic synthesis has been lacking. Here, we conduct a systematic review and meta-analysis to quantify FROH-fitness associations, identify drivers of variation and derive conservation-relevant recommendations. Narrative synthesis of 44 studies revealed that inbreeding depression operates through multiple interconnected pathways (survival, maternal effects, disease susceptibility, reproduction). Critically, purging cannot be relied upon to eliminate inbreeding depression as substantial fitness costs persist even in historically small populations. Meta-analysis of 62 effect sizes revealed a significant negative association between genomic inbreeding and fitness across taxa (Fisher's z = -0.103, r = -0.10, p < 0.0001). Study group, whether wildlife, livestock or humans, explained 22.5% of variance, with wildlife showing strongest effects (6-fold stronger than humans). Survival traits showed the greatest sensitivity to the effects of ROH (r = -0.22). Additionally, ROH detection methodology significantly influenced effect sizes: comprehensive approaches (all ROH lengths) detected stronger depression (r = -0.18) than long-ROH-only analyses (r = -0.08, p = 0.008), indicating cumulative genetic load matters. Overall, results indicate significant but variable fitness associations with ROH, with effect magnitude depending on biological context and methodological approach. Comprehensive ROH-based approaches show promise as conservation monitoring tools, but limited wildlife studies, particularly for non-mammalian taxa, highlight an urgent need for standardized protocols and expanded empirical research.

Animals↗

PubMed2008

Runs of homozygosity in European populations.

Estimating individual genome-wide autozygosity is important both in the identification of recessive disease variants via homozygosity mapping and in the investigation of the effects of genome-wide homozygosity on traits of biomedical importance. Approaches have tended to involve either single-point estimates or rather complex multipoint methods of inferring individual autozygosity, all on the basis of limited marker data. Now, with the availability of high-density genome scans, a multipoint, observational method of estimating individual autozygosity is possible. Using data from a 300,000 SNP panel in 2618 individuals from two isolated and two more-cosmopolitan populations of European origin, we explore the potential of estimating individual autozygosity from data on runs of homozygosity (ROHs). Termed F(roh), this is defined as the proportion of the autosomal genome in runs of homozygosity above a specified length. Mean F(roh) distinguishes clearly between subpopulations classified in terms of grandparental endogamy and population size. With the use of good pedigree data for one of the populations (Orkney), F(roh) was found to correlate strongly with the inbreeding coefficient estimated from pedigrees (r = 0.86). Using pedigrees to identify individuals with no shared maternal and paternal ancestors in five, and probably at least ten, generations, we show that ROHs measuring up to 4 Mb are common in demonstrably outbred individuals. Given the stochastic variation in ROH number, length, and location and the fact that ROHs are important whether ancient or recent in origin, approaches such as this will provide a more useful description of genomic autozygosity than has hitherto been possible.

Adolescent↗

PubMed2026

Whole-exome sequencing-centered genetic evaluation for early-onset obesity in Chinese children: a retrospective single-center cohort.

BACKGROUND: Genetic causes of early-onset obesity remain undercharacterized in East Asian children. This study evaluated a whole-exome sequencing (WES)-centered diagnostic workflow in Chinese children with obesity onset before 5 years. METHODS: Consecutive children with body mass index above the 95th percentile and obesity onset before 5 years who completed structured inpatient assessment at a single center between February 2022 and December 2023 were retrospectively analyzed. Phenotyping included clinical, biochemical, oral glucose tolerance, cortisol rhythm, and liver assessments. Genetic testing combined WES, mitochondrial DNA analysis, multiplex ligation-dependent probe amplification (MLPA) for obesity-related imprinting loci, WES-based copy-number variant and runs-of-homozygosity analyses, and Sanger validation. Variants were interpreted according to the American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) criteria. RESULTS: Among 23 children, clinically relevant genetic findings were identified in 6 (26.1%): melanocortin-4 receptor (MC4R) c.831T>A (p.C277*), maternal uniparental disomy of 15q11-13, and four phenotype-correlated variants of uncertain significance in UCP3, BBS1, NCOA1, and SH2B1. The definitive/likely diagnostic yield, restricted to pathogenic or confirmed imprinting findings, was 8.7% (2/23). Findings involved leptin-MC4R signaling, BBSome function, fatty-acid oxidation, and chromosomal imprinting. Genetically positive children showed numerically higher alanine aminotransferase (ALT) and aspartate aminotransferase (AST), but differences were not statistically significant. BBS1 p.T374S was relatively enriched in East Asian reference data. CONCLUSIONS: A WES-centered integrated workflow detected heterogeneous genetic mechanisms in Chinese children with early-onset obesity, but variant of uncertain significance (VUS)-associated findings should be distinguished from confirmed diagnoses. Orthogonal methylation/MLPA and runs of homozygosity (ROH) analyses were necessary for imprinting diagnosis. Larger multicenter studies and functional validation are needed.

Chinese children↗

PubMed2026

Genome-Wide Differentiation, Inbreeding, and Candidate Selection Loci in Local Vietnamese Pig Breeds.

Vietnam harbors exceptional genetic diversity among at least 26 indigenous pig breeds. We analyzed genome-wide single-nucleotide polymorphism (SNP) data from 90 animals representing 15 local Vietnamese breeds and six Landrace pigs using principal component analysis, the windowed fixation index (FST), cross-population extended haplotype homozygosity (XP-EHH), within-population integrated haplotype score (iHS), and runs of homozygosity (ROHs). The population structure was consistent with a north-south differentiation axis, and Ba Xuyen showed elevated heterozygosity, providing suggestive evidence of a European genetic contribution; the f3 statistic was positive (f3 = +0.015), and formal evidence of admixture requires a significantly negative f3, so this criterion was not met. Integration of FST and XP-EHH identified GPC5, E2F6, NOS1, and TLR4 as top Northern candidate loci and CRYM/ZP2 as the leading Central candidate locus, and these windows were recovered at both the 90th and 95th percentile thresholds, indicating analytical robustness rather than independent biological validation. iHS was elevated at E2F6 in Northern breeds (|iHS| = 3.04) and at NOS1 across all regional groups (|iHS| = 2.66-3.36). Breed-level phenotypic XP-EHH, based on published breed descriptions and coat color rather than individual body-composition measurements, identified GALNT2 as a candidate shared across breed groups; HCAR1 and ATG10 as candidates specific to the extreme-fat/prolific breed group; and EFNA5 and HIPK2 as candidates specific to the medium-bodied breed group. ROHs identified Soc, Co, and Hung as breeds warranting particular attention in conservation planning due to elevated autozygosity. Because each breed was represented by only six individuals, and because no individual-level phenotypic measurements were available, all findings are reported as exploratory population-genomic signals requiring replication in larger cohorts. Overall, we describe genomic differentiation and candidate selection signatures among local Vietnamese pig breeds and provide a foundation for further genomic studies of these breeds.

Animals↗

PubMed2026

Genotypic and phenotypic consequences of domestication in dogs.

Runs of homozygosity (ROH) are genomic regions that arise when identical haplotypes are inherited from a shared ancestor. In this study, we explored ROH across 556 whole-genome sequences from domesticated and non-domesticated dogs. Then, we leveraged ROH from 466 breed dogs, representing 13 breed groups and 13 phenotypic traits, to investigate associations between genetic diversity and non-disease phenotypes. We identified significant associations between the ROH-based inbreeding coefficient (FROH) and multiple phenotypes. These include three quantitative traits (height, weight, lifespan) and ten morphological and coat-related traits. After correcting for population structure, we identified more than 45 genes associated with quantitative traits that exceeded suggestive or genome-wide significance (GWS) thresholds. We also observed distinct patterns of inbreeding across dog populations, including elevated levels of long ROH in modern breed dogs relative to more ancient breeds, consistent with intensive breeding practices during Victorian-era breed formation. Together, our results demonstrate how domestication, demographic bottlenecks, and selective breeding have shaped patterns of homozygosity and contributed to the genetic architecture of complex traits in dogs, highlighting an important role for non-additive genetic variation and polygenicity.

Animals↗

PubMed2025

Conservation Arks: Genomic Erosion and Inbreeding in an Abundant Island Population of Koalas.

The persistence of many threatened species depends on isolated habitat patches such as conservation parks, fenced reserves, and islands. While these 'conservation arks' provide refuge from many contemporary threats, they can also pose risks of genetic diversity loss and inbreeding depression, further exacerbating extinction risk. A pertinent example is the Kangaroo Island koala population in South Australia that originated from a few translocated founding individuals in the 1920s but now sustains a large population with a low prevalence of infectious disease. We investigated the extent and consequences of founder effects on genomic diversity, inbreeding, and adaptive potential in Kangaroo Island koalas by comparing them with mainland Australian populations using high-coverage whole genomes. Our findings support sharp, recent declines in effective population sizes (Ne) in both mainland and Kangaroo Island populations. However, Kangaroo Island koalas had much lower individual and population-level diversity. Together with longer and more numerous runs of homozygosity and an increased proportion of homozygous genetic load, these results support the hypothesis that a severe bottleneck has contributed to inbreeding and maladaptation in Kangaroo Island koalas. While Kangaroo Island has the potential to conserve a viable population of koalas, we recommend genetic rescue to restore diversity and mitigate inbreeding depression in this isolated population. Our results emphasise the need for longitudinal genomic monitoring and genetic management to maintain long-term viability and resilience in potential conservation arks. Understanding the demographic history of such populations will help inform future conservation aimed at preventing genetic erosion and preserving biodiversity.

Animals↗

PubMed2025

Genotypic and phenotypic consequences of domestication in dogs.

Runs of homozygosity (ROH) are genomic regions that arise when two copies of identical haplotypes are inherited from a shared common ancestor. In this study, we leverage ROH to identify associations between genetic diversity and non-disease phenotypes in Canis lupus familiaris (dogs). We find significant association between the ROH inbreeding coefficient (FROH) and several phenotypic traits. These traits include height, weight, lifespan, muscled, white coloring of the head and chest, furnishings, and fur length. After correcting for population structure, we identified more than 45 genes across the examined quantitative traits that exceed the threshold for suggestive significance. We observe distinct distributions of inbreeding and elevated levels of long ROH in modern breed dogs compared to more ancient breeds, which aligns with breeding practices during Victorian era breed establishment. Our results highlight the impact of non-additive variation and of polygenicity on complex quantitative phenotypes in dogs due to domestication and the breed formation bottleneck.

GWAS↗

PubMed2026

Genomic diversity, inbreeding, and selection signatures in duroc, landrace, and yorkshire pigs from a long-term closed breeding system.

Duroc (DD), Landrace (LL), and Yorkshire (YY) are among the most widely used commercial pig breeds, having undergone intense long-term selection within closed breeding systems. This study presents a comprehensive genomic analysis of genetic diversity, inbreeding patterns, and selection signatures in DD, LL, and YY populations that have been subject to close breeding for over 15 years. Genomic and pedigree data were available for 1,088 animals (DD = 348, LL = 276, YY = 464), genotyped using the GenoBaits® Porcine 100 K SNP panel. Principal component analysis and genetic diversity metrics revealed distinct population structures among the three breeds. Pairwise genetic differentiation supported this pattern, with DD showing the greatest divergence from LL (0.34 ± 0.24) and YY (0.33 ± 0.24), while LL and YY were more closely related (FST = 0.22 ± 0.19). Linkage disequilibrium (LD) analysis further confirmed these differences, as DD exhibited the highest average r² (0.34), followed by LL (0.28) and YY (0.25). Within-breed genetic diversity metrics, including observed heterozygosity (HO: 0.37 in DD, 0.39 in LL, 0.38 in YY), expected heterozygosity (HE: 0.36 in DD, 0.37 in LL, 0.38 in YY), and minor allele frequency (MAF: 0.27 in DD, 0.28 in LL, 0.29 in YY), indicated greater genetic variability in LL and YY compared to DD. Runs of homozygosity (ROH) analyses revealed different patterns of autozygosity, with DD exhibiting more long ROH indicative of recent inbreeding, while YY harbored a higher number of short ROH, suggestive of more ancient demographic events. ROH-based inbreeding coefficients (FROH) consistently exceeded pedigree-based estimates (FPED) across all breeds, highlighting the presence of recent or unrecorded inbreeding that pedigree data may not fully capture. According to Generation Proxy Selection Mapping (GPSM), 17, 1, and 12 significant SNPs were detected in DD, LL, and YY, respectively. Functional annotation of ROH islands and GPSM-significant loci revealed both breed-specific and overlapping QTLs related to traits such as growth, reproduction, and carcass. In general, the findings of this study contribute to a deeper understanding of the genomic consequences of long-term closed breeding and provide reference information to support consideration of breeding strategies that balance continued selection for productivity with the maintenance of genetic diversity in modern commercial pig populations.

Animals↗

PubMed2026

Genomic inbreeding coefficients and inbreeding depression of semen production traits at genome-wide and chromosomal levels in Japanese Holstein bulls.

We aimed to estimate inbreeding coefficients and the effects of inbreeding depression on semen production traits at both the genome-wide and chromosomal levels. We utilized pedigree data for 19,921 animals, single nucleotide polymorphism (SNP) data on 5700 Japanese Holstein bulls, and 52,193 semen collection records from 775 bulls. We estimated 4 different inbreeding coefficients, namely a pedigree-based coefficient (FPED) and 3 genomic coefficients derived from SNP data. The genomic coefficients consisted of one based on the genomic relationship matrix (FGRM), one based on runs of homozygosity (ROH), and one based on homozygous-by-descent (HBD) segments (FHBD). These genomic coefficients were estimated at both the genome-wide and chromosomal levels. Furthermore, we investigated the effects of these coefficients on semen production traits: semen volume (VOL), sperm concentration (CON), sperm number (NUM), and sperm motility (MOT). In the genome-wide-level analysis, inbreeding coefficients increased markedly in bulls born after 2009, coinciding with the introduction of genomic selection. Significant inbreeding depression of VOL was found. At the chromosomal level, the inbreeding coefficients for most chromosomes showed a similar trend to the genome-wide metrics, although some (e.g., chr10 and chr20) exhibited a more pronounced trend. Suggestive inbreeding effects were detected on specific chromosomes for all traits (chr1 and chr22 for VOL, chr24 and chr29 for CON, chr1, chr12, and chr27 for NUM, chr10 and chr18 for MOT), including the traits that were not significant at the genome-wide level. Our results highlight that chromosomal-level analysis provides information complementary to whole-genome metrics, offering a more detailed perspective for managing inbreeding effects. To mitigate the adverse effects of inbreeding on semen production traits, future breeding programs would benefit from the control of inbreeding effects on high-risk chromosomal regions.

Genomic inbreeding coefficient↗

PubMed2024

Genome-wide scan for selection signatures in Mexican Sardo Negro Zebu cattle.

The Sardo Negro cattle (SN) is the only zebu cattle breed developed in Mexico. Since its development, the selection could have led to an increase in the homozygosity level in some regions of the genome and made differentiation with other cattle populations. We aimed to identify and characterize selection signatures in SN using medium-density SNP data using four approaches: 1) Runs of homozygosity (ROH) 2) Nucleotide Diversity 3) Tajima's D and 4) the Wright's fixation index (FST). A sample of 555 SN animals genotyped for 65k SNPs was used to obtain ROH segments considered regions under selection. The FST values were estimated by comparing the sample of genotyped SN animals with samples of genotyped animals from the Gir, Brahman, and Ongole breeds. Only one region mapped to 35.78-42.51 Mb on BTA6 was considered a selection signature by the ROH method. This selection signature overlapped with the lowest diversity, negative values of Tajima's D and a diversification region between SN and the other Zebu breeds by FST. We found several candidate genes (LCORL, NCAPG, and SLIT2) related to growth and other economically important productive traits in this common region. Using the FST method, different regions, such as regions on BTA8 (8:93.4-93.9 Mb), BTA11 (11:99.2-99.7), and BTA14 (14: 26.1-26.8) related to growth and milk traits also were defined as candidate selection signatures. The selective signals identified in this study reflected the direction of the selection pressure that primarily involves the increase of live weight traits in the Sardo Negro cattle breeding program.

Animals↗

PubMed2026

Genetic structure and selection signatures of Beijing-You chicken populations provide insight into breed conservation.

Preserving genetic diversity and maintaining population viability are critical yet challenging goals that demand rigorous evaluation of conservation strategies. Beijing-You chicken, as the sole indigenous chicken breed originating from Beijing, China, is currently maintained as four independent populations under distinct conservation programs. How different conservation regimes have shaped its genomic architecture remains largely unknown, limiting evidence-based evaluation. Here, we generated whole-genome resequencing data from 240 individuals representing four Beijing-You chicken populations to assess population structure, genetic diversity, and signatures of selection over decades of conservation. All four populations formed distinct clusters, reflecting measurable differentiation after decades of separate conservation. The differences in genetic diversity were broadly consistent with the variation in effective population size estimates. Runs of homozygosity and linkage disequilibrium decay patterns further characterized each population, with extended values indicating reduced effective population size and increased inbreeding under long-term conservation. We applied the fixation index (FST) and pairwise diversity ratio (θπ) methods to identify selection signatures. A total of 171 genes were identified as candidates. These genes were enriched in pathways related to reproduction, growth regulation, and environmental adaptation. These findings highlight patterns of reduced diversity and skewed relatedness, which could arise from management-related factors such as breeding preferences or mating strategies. Still, they are also compatible with neutral processes, including drift and founder effects. Regardless of the underlying cause, integrating scientifically informed conservation strategies with routine genomic monitoring across generations is essential for sustaining genetic diversity in Beijing-You chicken and other indigenous breeds.

Beijing-You chicken↗

PubMed2025

Genomic analysis of differentiation and demography of the formerly conspecific agile (Dipodomys agilis) and Dulzura (D. simulans) kangaroo rats.

Karyotype variation within Pacific kangaroo rat Dipodomys agilis motivated its division in 1997 into the agile kangaroo rat (AKR, D. agilis, 2N = 62) in the north of its range in California, and Dulzura kangaroo rat (DKR, D. simulans, 2N = 60) to the south, with a suspected sympatric zone south of the San Gabriel and San Bernardino Mountains. This division was supported by our whole genome sequencing that sampled a ~120 km transect from north of the mountains to SW Riverside County. The taxa showed marked genetic differentiation, with no evidence of hybridization or sympatry. AKR was found at the southern edge of the mountains, precluding the mountain barrier driving isolation, suggesting ecological separation linked to habitat differences between the mountains and the arid area to the south. Adding four additional Dipodomys species, we estimated genetic divergence times in the genus back to ∼3.5 mya. AKR and DKR diverged from D. stephensi ∼1.7 mya, and from each other ∼0.5 mya, when their joint effective population size (Ne) was ~100,000. After separation, DKR's Ne declined to ~20,000, while AKR's was little changed. More recently their Ne converged at ~50,000. Runs of homozygosity were longer in AKR, indicating a smaller neighborhood size, which may have promoted the karyotype change; however, nucleotide diversity was higher in AKR, but both had levels typical for rodents, indicating neither experienced recent bottlenecks. These patterns provide a baseline for any future conservation efforts. More generally, this study shows how a detailed genomic study can resolve taxonomic and demographic questions among morphologically indistinguishable taxa.

Animals↗

PubMed2026

Sexual selection purges mutation load, but not overall genetic diversity, decreasing vulnerability to extinction.

Theory suggests sexual selection will enhance population viability by purging deleterious alleles. However, direct genomic evidence for this fundamental idea is scarce and contradictory. We combined long-term experimental evolution with whole-genome resequencing to directly test how sexual selection affects mutation load, genomic divergence, and extinction risk in small populations (maximum Ne = 40) of Tribolium castaneum. After 156 generations, populations evolving under strong sexual selection carried substantially fewer deleterious alleles than populations under weak sexual selection, based on both individual-level estimates of missense and nonsense variants and population-level Rxy analyses, indicating more efficient purging of deleterious alleles. In contrast, nucleotide diversity and runs of homozygosity were similar across treatments, indicating that purging acted most strongly on deleterious variation, and that reduced mutation load in these small populations under strong sexual selection was not explained by demographic effects. Importantly, population-level mutation load estimates best explained extinction risk under inbreeding, directly linking sexual selection to purging and population viability. Genome scans of high and low sexual selection populations revealed peaks of divergence, which included genes involved in courtship, sex discrimination, and seminal fluid proteins. Our results provide direct genomic evidence that sexual selection can reduce mutation load without eroding standing genetic diversity and thus adaptive potential, while driving adaptive divergence in reproductive traits. This beneficial purging may help explain the widespread prevalence of sexual reproduction in nature despite inherent costs and have important ramifications as to how we manage populations of conservation concern.

Animals↗

PubMed2026

Museum specimens reveal the genomic consequences of long-term population decline in an insect pollinator.

Global insect pollinator populations are under threat, with reported declines attributed to increasing habitat loss, pesticide use, and disease. Tracking how genetic diversity has changed over time could reveal the rate and extent of these declines, and the adaptive capacity of affected species-providing an important complement to habitat-based conservation efforts. However, few studies have been able to reconstruct suitable historical baselines to link genomic changes with population change. Here, we use whole genome data from 101 museum specimens of the declining moss carder bumblebee (Bombus muscorum) collected across Britain and Ireland between 1894 and 2019 to reveal a dramatic drop in genetic diversity over the last century. We find a substantial (∼24.6%) reduction in genome-wide heterozygosity across Britain during this period. In England and Wales, where habitat fragmentation is most pronounced, we observe a 2.86-fold increase in runs of homozygosity, commensurate with population fragmentation and isolation. Our results reveal the extent to which human-induced environmental change can lead to severe decadal-scale genomic erosion in a functionally important insect. Identified using DNA from historic museum collections, our approach has widespread applicability for insect conservation and understanding the evolutionary consequences of environmental change.

Animals↗

PubMed2025

Characterisation of the Historic Demographic Decline of the British European Polecat Population.

The European polecat (Mustela putorius) has a widespread distribution across many countries of mainland Europe but is documented to be declining within these ranges. In Britain, direct persecution led to a severe decline of the polecat population during the 19th century. Unlike European mainland populations, it is now recovering across much of its former British range. The genomic and conservation implications of such a severe demographic decline, followed by the current recovery, have still to be characterised in the European polecat in Britain. Here we carry out population-level whole-genome analyses of 65 polecats from Britain (Wales and England) and the European mainland. Our analyses reveal that Welsh polecats show genetic variability from both English and European polecats, while British polecats as a whole exhibit signs of genetic isolation from mainland European populations. We also reconstructed the demographic history of the Welsh polecat to quantify the magnitude of the bottleneck. Our analyses confirmed the drastic decline of the Welsh polecat's effective population size, with a severe genetic bottleneck around 30-40 generations ago (1854-894). We investigated whether whole-genome diversity reflected this demographic event and found that Welsh polecats had significantly less genetic diversity than English polecats, but not European polecats. Runs of homozygosity and genetic load present in Welsh and English polecat genomes also indicated recent historic inbreeding. Our findings suggest that the increase in the British polecat population size may be attributed to admixture events. Additionally, we demonstrate that the Welsh polecat constitutes a genetically distinct population, which could be crucial for the overall conservation of European polecats by preserving unique genetic diversity.

Genetics, Population↗

PubMed2026

Integration of Morphological and Genome-Wide SNP Data Reveals Regional Diversity in Thai Swamp Buffalo.

Thai swamp buffalo (Bubalus bubalis) are valuable animal genetic resources, but their regional diversity remains incompletely characterized. Morphological records were obtained from 799 buffaloes, and 474 individuals were genotyped using the 90K Axiom® Buffalo SNP Genotyping Array (Thermo Fisher Scientific, Applied Biosystems™, Santa Clara, CA, USA). Qualitative traits included coat color, horn shape, chevron pattern, and hair-whorl distribution, while quantitative characterization covered 30 body measurements. After excluding missing traits, 30 traits adjusted for sex, age, province, and farm from 768 animals were used for morphology-based analyses, which identified regional phenotypic differences but also substantial overlap, consistent with the influence of feeding, management, environment, and local selection on body conformation. Genome-wide SNP analyses indicated a broadly shared genetic background with detectable regional structure, and runs of homozygosity revealed regional differences in genomic autozygosity. The Lower South showed a comparatively strong recurrent-ROH pattern, whereas inference for the Upper South requires caution because of its small genomic sample. Overall, integrating morphology and genome-wide SNP data improves regional characterization, but data-dependent statistics, population-structure estimates, and conservation implications should be interpreted while regarding small sampling and unbalanced data.

Bubalus bubalis↗

PubMed2026

Whole-Genome Sequencing Reveals Population Structure, Genetic Diversity, and Selection Signatures in Kazakh Dromedary and Bactrian Camels.

Understanding the genomic basis of environmental adaptation is essential for the conservation and genetic improvement of domestic camels. In this study, we investigated the population structure, genetic diversity, and genomic variation potentially associated with environmental adaptation of Kazakh dromedary and Bactrian camels using whole-genome sequencing. Whole-genome sequencing data were generated for Kazakh camels (15 dromedaries and 16 Bactrian camels) and integrated with 131 publicly available genomes representing camel populations from the Arabian Peninsula, Iran, Xinjiang, Inner Mongolia, and Mongolian wild camels. Population structure, genetic diversity, and genome-wide selection were evaluated using principal component analysis, ADMIXTURE, nucleotide diversity, linkage disequilibrium, runs of homozygosity, genomic inbreeding (FROH), and selection scans based on FST, θπ ratio, and XP-EHH. Population genomic analyses revealed clear differentiation between dromedary and Bactrian camels, whereas Kazakh camel populations exhibited higher nucleotide diversity (θπ = 1.307-1.551 × 10-3), and lower genomic inbreeding (median FROH: 0.037-0.056) than Arabian populations. Genome-wide selection analyses identified MC4R as the prominent candidate gene in Kazakh dromedaries and RYR1 as a prominent candidate gene in Kazakh Bactrian camels. Functional enrichment analyses highlighted pathways related to energy metabolism, thermogenesis, calcium signaling, skeletal muscle function, mitochondrial activity, and oxidative stress response. These findings provide new insights into genomic variation potentially associated with environmental adaptation in Kazakh camels and offer valuable genomic resources for future conservation, breeding, and evolutionary studies.

MC4R↗

PubMed2026

Genome-wide SNP-based genomic diversity and population structure analysis in alpaca populations from Europe and Peru.

This study aimed to analyze the genetic diversity and population structure of alpacas in Germany, Switzerland, and Austria (German-speaking regions, GSR) and to compare with that of the country of origin of the species (Peru). A total of 179 animals from GSR and 151 from Peru were genotyped with a species-specific 76k SNP array. The observed and expected heterozygosity was 0.305 and 0.311 for GSR and 0.310 and 0.312 for Peru. The mean FROH values were 0.029 for GSR and 0.023 for Peru. In general, results show that breeders in both analyzed regions efficiently maintain genetic diversity. Principal component analysis identified the GSR and Peru populations as separate from each other, but the relative proximity of both clusters indicates the shared genetic heritage. FST and XPEHH methods identified genomic regions under selection for traits such as coat color and adaptation. Genome-wide association studies comparing black and brown with white or gray alpacas identified associated genome regions containing the ASIP and KIT genes, respectively. The association of a recently identified keratin locus on chromosome 16 with differences in fleece type in alpacas was confirmed, while the putative causality of a TRPV3 variant was rejected.

Animals↗