Population Genetic Differences Research Articles

Genomic characterization and diversity assessment of eight endangered Belgian sheep breeds

Assessing the genetic diversity of local breeds is essential for conserving these unique breeds, which may possess unique traits. This study provides the genomic characterization of eight indigenous sheep breeds in Belgium based on pedigree and single nucleotide polymorphism (SNP) analysis. A total of 687 sheep were genotyped and were subjected to a rigorous quality control, resulting in a set of 45,978 autosomal SNPs. Pedigree analysis showed breed-average inbreeding estimates between 3.3% and 11.3%. The genomic analysis included an assessment of runs of homozygosity (ROH) to examine the genomic inbreeding coefficient, with breed-average inbreeding coefficients estimated between 4.1% and 8.5%. ROH islands were identified in six of the eight breeds studied, with some exhibiting an incidence up to 58%. Interestingly, several ROH islands overlapped with other breeds included in this study, as well as with international sheep breeds. Pedigree-based effective population sizes were estimated below 100 for all breeds, whereas genomic-based effective population sizes were below 24, indicating that these eight local sheep breeds are endangered. Principal component analysis, admixture analyses, and Fst computations were used to study the population structure and genetic differences. A neighbor joining tree using 95 international sheep breeds positioned the eight local breeds in the group of milksheep, Texel sheep and the Scandinavian breeds. Additionally, the investigation of paternal oY1 genotypes revealed diverse lineage origins within the Belgian sheep population. This study refines and deepens our knowledge about the local sheep breeds in Belgium, thereby improving their management and conservation. Moreover, as these breeds are linked to other international breeds, these insights are significant for the global scientific community.

Phylogeography of a commercially important reef fish, Lutjanus ehrenbergii, from the coastal waters of the Arabian Peninsula

Abstract The coastal waters of the Arabian Peninsula include a heterogeneous marine region comprising the Persian/Arabian Gulf and Sea of Oman at its northeastern boundary and the Arabian Sea, Gulf of Aden, and Red Sea at its southern and western boundary. The environment within this region shifts from highly variable coral cover and extreme temperatures within the Persian/Arabian Gulf to sparse coral cover, lower summer temperatures, and nutrient-rich upwelling within the Sea of Oman. Within the Gulf of Aden and Red Sea there is high coral cover and warm, stable conditions. We tested for barriers to pelagic dispersal across this peninsula for the commercially important blackspot snapper Lutjanus ehrenbergii using mitochondrial DNA sequences. We found scant evidence for population genetic differences when comparing within northern and southern sections, but instead found strong evidence of genetic differentiation between northern and southern sections, with the Persian/Arabian Gulf and Sea of Oman populations being highly differentiated from the Gulf of Aden and Red Sea populations. Low levels of haplotype sharing between the Persian/Arabian Gulf – Sea of Oman and the Gulf of Aden – Red Sea probably reflect scenarios of historical colonization into these peripheral bodies of water, or the presence of a contemporary ecological barrier preventing further genetic exchange.

Prevalence of intestinal parasitic infections and genetic differentiation of Strongyloides stercoralis among migrant workers from Myanmar, Lao PDR and Cambodia in northeastern Thailand.

Intestinal parasitic infections (IPIs) remain a public-health problem worldwide, including in countries of the Lower Mekong subregion. Increases in human migration from neighboring countries might cause reemerging parasitic infections, leading to spread of parasites in the landscape. Here, we conducted a cross-sectional study to identify the prevalence of IPIs in migrant workers from Myanmar, Lao PDR, and Cambodia who were dwelling in Nakhon Ratchasima Province, northeastern Thailand. The identification of Strongyloides species and genetic differentiation of worms from migrant workers with different countries of origin was also assessed. Fresh stool samples were collected from 338 migrant workers and examined for evidence of IPIs using agar plate culture (APC) and the formalin-ethyl acetate concentration technique (FECT). Among those nine samples positive for nematodes by APC, the Strongyloides or hookworm species present was confirmed using the polymerase chain reaction (PCR) followed by DNA sequencing. This revealed eight cases of Strongyloides stercoralis infection and one of Necator americanus. Fifty-one out of 338 individuals (15.09%) were positive for IPIs using FECT and APC. Eggs of Opisthorchis-like flukes were the most common parasite (11.83% of samples), followed by S. stercoralis (2.37%), Entamoeba coli (1.50%), hookworm (0.89%), Taenia sp. (0.60%) and Hymenolepis nana (0.30%). The genetic differentiation of S. stercoralis recovered from migrant workers with different countries of origin was analyzed. Specimens of S. stercoralis isolated from workers from Lao PDR, Cambodia and Myanmar were genetically similar to those sequenced from Thailand. However, there were population-genetic differences between S. stercoralis from these Southeast Asian countries and other regions of the world. This study demonstrated that IPIs were prevalent in migrant workers in the northeastern region of Thailand. Our findings provided molecular confirmation of the presence of S. stercoralis and explored the genetic differentiation of S. stercoralis from those infected migrant workers. An effective anti-parasitic drug should be provided for migrant workers and its administration enforced.

Contrasting genetic diversity and structure between endemic and widespread damselfishes are related to differing adaptive strategies

AbstractAimSeveral marine biogeographical provinces meet at the Arabian Peninsula. Where and how these junctions affect species is poorly understood. We herein aimed to identify the barriers to dispersal and how these shape fish populations, leading to differing biogeographies despite shared habitat and co‐ancestry.TaxonDascyllus marginatus (endemic) and Dascyllus abudafur (widespread).LocationCoral reefs from the Red Sea (RS), Djibouti, Yemen, Oman, and Madagascar.MethodsWe tested potential barriers to gene flow using RADseq‐derived SNPs and identified whether population genetic differences on each side of these barriers were neutral or selective to relate this to the biogeography of the species. Seven locations (ranging over 5100 km) were sampled for the endemic and six (ranging over 7400 km) for the widespread species, taking 20 individuals per location, with two exceptions.ResultsDascyllus marginatus populations (comprising 5648 SNPs) had an order of magnitude higher genetic differentiation compared to D. abudafur (comprising 10,667 SNPs), as well as several outlier loci that were absent in D. abudafur despite equal sampling locations. In both species, the RS and Djibouti specimens formed one genetic cluster separated from all other locations. Although ranging from the RS to Madagascar, D. abudafur was absent in Yemen and Oman.Main ConclusionsStronger genetic structure at smaller geographical scales and outlier loci in the endemic species seem associated with faster adaptation to environmental differences and selective pressure. Genetic differentiation in the widespread species is neutral and only occurs at large geographical distances. Restrictive transitions (between the Gulf of Aqaba and the RS or the RS and the Gulf of Aden) do not hinder gene flow in either species, and the environmental shift within the RS (at 22°N/20°N) only affected the endemic species. The genetic break in the Gulf of Aden likely reflects historical colonization processes and not contemporary environmental regimes.

Reduced representation sequencing to understand the evolutionary history of Torrey pine (Pinus torreyana parry) with implications for rare species conservation.

Understanding the contribution of neutral and adaptive evolutionary processes to population differentiation is often necessary for better informed management and conservation of rare species. In this study, we focused on Pinus torreyana Parry (Torrey pine), one of the world's rarest pines, endemic to one island and one mainland population in California. Small population size, low genetic diversity, and susceptibility to abiotic and biotic stresses suggest Torrey pine may benefit from interpopulation genetic rescue to preserve the species' evolutionary potential. We leveraged reduced representation sequencing to tease apart the respective contributions of stochastic and deterministic evolutionary processes to population differentiation. We applied these data to model spatial and temporal demographic changes in effective population sizes and genetic connectivity, to identify loci possibly under selection, and evaluate genetic rescue as a potential conservation strategy. Overall, we observed exceedingly low standing variation within both Torrey pine populations, reflecting consistently low effective population sizes across time, and limited genetic differentiation, suggesting maintenance of gene flow between populations following divergence. However, genome scans identified more than 2000 candidate SNPs potentially under divergent selection. Combined with previous observations indicating population phenotypic differentiation, this indicates natural selection has probably contributed to the evolution of population genetic differences. Thus, while reduced genetic diversity, small effective population size, and genetic connectivity between populations suggest genetic rescue could mitigate the adverse effects of rarity, evidence for adaptive differentiation suggests genetic mixing could disrupt adaptation. Further work evaluating the fitness consequences of inter-population admixture is necessary to empirically evaluate the trade-offs associated with genetic rescue in Torrey pine.

The complete mitochondrial genomes of the flapper skate Dipturus intermedius and the longnose skate Dipturus oxyrinchus

We describe the complete mitochondrial genomes of the flapper skate Dipturus intermedius (Parnell 1837) and the longnose skate Dipturus oxyrinchus (Linnaeus 1758), which have been obtained by Sanger sequencing. We report the length of the sequences to be 16,906 and 16,911 bp, respectively. The length and structure of gene regions, containing 13 protein-coding regions, 22 tRNA genes, two rRNA genes, and two non-coding areas, resemble those of related skate species. Despite D. intermedius being considered a cryptic species with D. batis, the full mitogenomes confirm that D. intermedius and D. oxyrinchus are more genetically similar. In comparison to other Dipturus species, D. intermedius is missing a whole codon in its cytochrome oxidase subunit 2 gene. These mitogenomes will be a useful resource furthering investigation of the population genetic differences and evolutionary history of skate species.

Progress of research on polymorphisms of common drug metabolism related genes among various populations in China

Genetic background can lead to differences in drug effects among different populations when they use the same drug. To delineate the pharmacogenomics and population genetic differences may help to clarify the role of polymorphisms of drug metabolism-related genes in drug effect heterogeneity among different populations. This article has summarized the latest progress on the polymorphisms of drug metabolism-related genes among different populations in China.

Genome-Wide Selective Signatures Reveal Candidate Genes Associated with Hair Follicle Development and Wool Shedding in Sheep.

Hair follicle development and wool shedding in sheep are poorly understood. This study investigated the population structures and genetic differences between sheep with different wool types to identify candidate genes related to these traits. We used Illumina ovine SNP 50K chip genotyping data of 795 sheep populations comprising 27 breeds with two wool types, measuring the population differentiation index (Fst), nucleotide diversity (θπ ratio), and extended haplotype homozygosity among populations (XP-EHH) to detect the selective signatures of hair sheep and fine-wool sheep. The top 5% of the Fst and θπ ratio values, and values of XP-EHH < −2 were considered strongly selected SNP sites. Annotation showed that the PRX, SOX18, TGM3, and TCF3 genes related to hair follicle development and wool shedding were strongly selected. Our results indicated that these methods identified important genes related to hair follicle formation, epidermal differentiation, and hair follicle stem cell development, and provide a meaningful reference for further study on the molecular mechanisms of economically important traits in sheep.

Laryngeal cancers in paediatric and young adult patients: epidemiology, biology and treatment.

The aim of thi study was to review the recent literature on epidemiology, biology and treatment of laryngeal cancer in paediatric and young adult patients. Epidemiological studies reported that 2-10% of patients with laryngeal cancer are younger than 40-year-old, while the prevalence of laryngeal cancer remains unknown in the paediatric population. The development of laryngeal cancer in young adults is multifactorial and may be linked to common carcinogens (tobacco and alcohol), occupational factors, laryngopharyngeal reflux, immunosuppression, human papillomavirus infection and genetic polymorphism. A substantial number of cohort studies reported a significant lower proportion of drinkers and smokers in young populations with laryngeal cancer, supporting the higher prevalence of chromosomal losses or abnormalities predisposing to cancer in this group. The development of laryngeal cancer in paediatric patients is strongly associated with genetic syndromes with DNA repair abnormalities. The pathological, clinical and survival outcome differences between young and old patient groups vary significantly between studies, depending on epidemiological, genetic features and therapeutic strategies used. Paediatric and adult populations with laryngeal cancer present different clinical, pathological and survival outcomes. In the adult population, the patient age at the time of disease development underlies genetic and etiological differences with different mutation patterns between young and old patients, the latter being more frequently individuals with a history of tobacco and alcohol abuse. The differences between age groups regarding stage of cancer at initial presentation, as well as clinical and survival outcomes, are unclear, which may be due to demographic, ethnicity and population genetic differences.

AI-SNPs screening based on the whole genome data and research on genetic structure differences of subcontinent populations.

The genetic structure differences in population is one of the key elements in medical research involving multi-population samples. A set of ancestry-informative single nucleotide polymorphisms (AI-SNPs) can be utilized to analyze genetic component of a population, infer ancestral origin of individuals and pre-filter samples to reduce the impact of population genetic structure differences on medical research. However, most of the published studies were focused on revealing the differences between populations of continents or regions of a continent. In this paper, AI-SNPs were screened by calculating FST value in each pair of five East Asian populations: Japanese in Tokyo (JPT), Han Chinese in Beijing (CHB), Southern Han Chinese (CHS), Chinese Dai in Xishuangbanna (CDX) and Kinh in Ho Chi Minh City (KHV) in the 1000 Genomes Project phase 3 (GRCh37.p13) to analyze differences in subcontinent populations. The results demonstrate that the five East Asian populations in our study were assigned to three clusters: JPT, CHB and CHS, CDX and KHV. A set of AI-SNPs can be used for analysis of individual genetic composition and selection of representative individuals. Individuals with over 80% population representative genetic components have good representativeness of a population. This paper demonstrated the practical value of the method, which was performed to verify the ancestral composition and select representative samples with a panel of screened AI-SNPs by FST value, thereby reducing the influence of genetic structure differences in subcontinent populations on population-related medical research.

A comparative analysis of kratom exposure cases in Thailand and the United States from 2010-2017

ABSTRACT Background: Interest in the Southeast Asian natural remedy kratom has increased in Western countries recently, along with increasing concern over its potential toxic effects. Objective: To describe and compare demographics, common co-exposure substances, clinical effects, treatments, and medical outcomes of kratom “abuse” exposures in the United States (US) and Thailand. Methods: This is a retrospective analysis of kratom “abuse” exposures, defined as use when attempting to gain a psychotropic effect, reported to the National Poison Data System (NPDS) in the US and the Ramathibodi Poison Center (RPC) in Thailand from 2010 to 2017. Multivariate analysis identified risk factors for severe medical outcomes, defined as both ICU admissions and death. Results: Nine-hundred-twenty-eight cases were included (760 from NPDS and 168 from RPC). A greater proportion of cases involved co-exposures in Thailand (64.8% versus 37.4%; odds ratio [OR] = 3.10, 95% confidence interval [CI] = 2.15–4.47, p < .01). Both countries had a similar prevalence of opioid and benzodiazepine co-ingestions, but the US had more co-ingestions with other sedatives (4.6% versus 0%, OR = 0, 95% CI = 0–0.47, p < .01). Common clinical effects included tachycardia (30.4%), agitation/irritability (26.2%), and drowsiness/lethargy (21.1%). Six deaths occurred, including one single-substance exposure in the US, three multiple-substance exposures in the US, and two multiple-substance exposures in Thailand. Severe medical outcomes were reported more frequently in the US (OR = 18.82, 95% CI = 5.85–60.56, p < .01). Conclusions: Despite lower frequencies of co-ingestants overall, US kratom abuse exposures yielded greater clinical severity. This disparity may be attributable to differences in the products labeled “kratom,” greater sedative co-exposures in the US, and/or differences in population genetics or use patterns.

Decoding the great ape Y

Genomics The Y chromosome confers maleness in most mammals and in other species, including flies and some plants. Studies of this chromosome and its evolutionary history can inform upon evolutionary lineages and the genes involved in male fertility. However, the Y chromosome has been difficult to sequence; because of its high content of repetitive DNA and low gene number, it is often absent from genomic assemblies. Cechova et al. generated draft sequences of the bonobo and orangutan Y chromosomes and compared them with previously sequenced human, gorilla, and chimpanzee Y chromosomes. By comparing the Y chromosomes of all great ape species, this study provides resources for understanding the evolution of this chromosome, which can help explain population genetic differences within and between these species and may aid in conservation for our endangered closest relatives. Proc. Natl. Acad. Sci. U.S.A. 117 , 26273 (2020).

Using environmental and geographic data to optimize ex situ collections and preserve evolutionary potential.

Maintenance of biodiversity through seed banks and botanical gardens, where the wealth of species' genetic variation may be preserved ex situ, is a major goal of conservation. However, challenges can persist in optimizing ex situ collections if trade-offs exist among cost, effort, and conserving species evolutionary potential, particularly when genetic data are not available. We evaluated the genetic consequences of population preservation informed by geographic (isolation by distance [IBD]) and environmental (isolation by environment [IBE]) distance for ex situ collections for which population provenance is available. We used 19 genetic and genomic data sets from 15 plant species to assess the proportion of population genetic differentiation explained by geographic and environmental factors and to simulate ex situ collections prioritizing source populations based on pairwise geographic distance, environmental distance, or both. Specifically, we tested the impact prioritizing sampling based on these distances may have on the capture of neutral, functional, or putatively adaptive genetic diversity and differentiation. Individually, IBD and IBE explained limited population genetic differences across all 3 genetic marker classes (IBD, 10-16%; IBE, 1-5.5%). Together, they explained a substantial proportion of population genetic differences for functional (45%) and adaptive (71%) variation. Simulated ex situ collections revealed that inclusion of IBD, IBE, or both increased allelic diversity and genetic differentiation captured among populations, particularly for loci that may be important for adaptation. Thus, prioritizing population collections based on environmental and geographic distance data can optimize genetic variation captured ex situ. For the vast majority of plant species for which there is no genetic information, these data are invaluable to conservation because they can guide preservation of genetic variation needed to maintain evolutionary potential within collections.

Unravelling selection signatures in a single dog breed suggests recent selection for morphological and behavioral traits.

Strong selection has resulted in substantial morphological and behavioral diversity across modern dog breeds, which makes dogs interesting model animals to study the underlying genetic architecture of these traits. However, results from between-breed analyses may confound selection signatures for behavior and morphological features that were coselected during breed development. In this study, we assess population genetic differences in a unique resource of dogs of the same breed but with systematic behavioral selection in only one population. We exploit these different breeding backgrounds to identify signatures of recent selection. Selection signatures within populations were found on chromosomes 4 and 19, with the strongest signals in behavior-related genes. Regions showing strong signals of divergent selection were located on chromosomes 1, 24, and 32, and include candidate genes for both physical features and behavior. Some of the selection signatures appear to be driven by loci associated with coat color (Chr 24; ASIP) and length (Chr 32; FGF5), while others showed evidence of association with behavior. Our findings suggest that signatures of selection within dog breeds have been driven by selection for morphology and behavior. Furthermore, we demonstrate that combining selection scans with association analyses is effective for dissecting the traits under selection.

Spatial genetic structure of a keystone long-lived semiarid shrub: historical effects prevail but do not cancel the impact of recent severe habitat loss on genetic diversity

Land-use conversion and habitat loss and degradation are among the factors affecting populations and species genetic integrity. Understanding how these factors govern the genetic structure of threatened plant populations is essential to design efficient conservation strategies. Here we analyze how environmental correlates, geographic location and anthropogenic disturbance (at local, landscape and regional scales) relate to population differentiation and genetic diversity of a keystone semiarid long-lived shrub, Ziziphus lotus. The European range of this species is restricted mainly to the southeast of the Iberian Peninsula (> 90%) but its area has shrunk considerably as a consequence of intensive agriculture and urban expansion since the 1950s. We characterize its genetic diversity and structure across the Iberian Peninsula with microsatellite markers, considering 21 populations. All populations showed high and relatively similar values of genetic diversity (mean/pop: Ho = 0.54; He = 0.55; AR = 3.59). Three main genetic clusters were defined by clustering analyses corresponding largely to west, central (core) and east of its distribution. Molecular variance analysis revealed that 87.3% of genetic variation was grouped within populations, 5% among populations and 7% between regions. Geographic location (37.88%) has stronger correlation with population genetic differences than landscape characteristics (5.82%). Natural habitat cover at the landscape level was the only environmental variable associated with FST population differences. The detected population genetic patterns are probably related primarily to historical gene flow and secondarily to intensive land-use change of this area in the last 60 years. Our results suggest that, although the long-lived and resprouting strategy of the species is buffering the erosion of genetic diversity at population and regional level, there are already genetic consequences of landscape degradation, which could be aggravated in the future.

Discovery of selection-driven genetic differences of Duroc, Landrace, and Yorkshire pig breeds by EigenGWAS and Fst analyses.

Pigs are one of the earliest domesticated animals and multiple breeds have been developed to meet the various demands of consumers. EigenGWAS is a novel strategy to identify candidate genes that underlying population genetic differences and to infer candidate regions under selection as well. In this study, EigenGWAS and Fst analyses were performed using the public re-sequencing data of three typical commercial pig breeds, Duroc, Landrace and Yorkshire. The intersection of genome-wide significant SNPs detected by EigenGWAS and top-ranked 1% SNPs of Fst results were treated as signals under selection. Using the data of all three breeds, 3062 signals under selection were detected and the nearby genomic regions within 300kb upstream and downstream covered 6.54% of whole genome. Pairs of breeds were analysed along with the pathway analysis. The gene function enrichment results indicated that many candidate genes located in the genomic regions of the signals under selection were associated with biological processes related to growth, metabolism, reproduction, sensory perception, etc. Among the candidate genes, the FSHB, AHR, PTHLH, KDR and FST genes were reported to be associated with reproductive performance; the KIT, KITLG, MITF, MC1R and EDNRB genes were previously identified to affect coat colour; the RETREG1, TXNIP, BMP5, PPARD and RBP4 genes were reported to be associated with lipid metabolism and growth traits. The identified genetic differences across the three commercial breeds will advance understanding of the artificial selection history of pigs and the signals under selection will suggest potential uses in pig genomic breeding programmes.

Comparative genomic analysis of three co-occurring annual Asteraceae along micro-geographic fragmentation scenarios

This is the first population genomic analysis that examines micro-evolutionary changes in co-occurring plant species, in fragmented habitats, along a precipitation gradient. We applied Genotype-by-Sequencing (GBS) on three different annual Asteraceae on the same sites that share similar life history strategies, but different pollination and dispersal strategies (Catananche lutea, Geropogon hybridus, Urospermum picroides).We tested if the genetic diversity for all species correlates with effective population sizes along the precipitation gradient and whether therefore genetic drift drives evolution at range edges. However, our results support this hypothesis for only one species (C. lutea) but refute it for the other two. Potential genomic signals of adaptation to the high precipitation gradient were found only in one species (U. picroides). We also tested if species with complex pollination and diversified dispersal strategies are less affected by small scale habitat fragmentation, but the opposite is true. Biological differences between the species studied (pollination and dispersal) explain population genetic differences along the precipitation gradient at range edges rather than environmental filters. Pairwise correlation analyses showed no or only weak similarities in the accumulation of mutations in the different species.Our results suggest that the processes driving evolution in different co-occurring species are different, so that most genomic similarities in our investigations may only represent temporary stages in evolution.

Faster speciation of fig-wasps than their host figs leads to decoupled speciation dynamics: Snapshots across the speciation continuum.

Even though speciation involving multiple interacting partners, such as plants and their pollinators, has attracted much research, most studies focus on isolated phases of the process. This currently precludes an integrated understanding of the mechanisms leading to cospeciation. Here, we examine population genetic structure across six species-pairs of figs and their pollinating wasps along an elevational gradient in New Guinea. Specifically, we test three hypotheses on the genetic structure within the examined species-pairs and find that the hypothesized genetic structures represent different phases of a single continuum, from incipient cospeciation to the full formation of new species. Our results also illuminate the mechanisms governing cospeciation, namely that fig wasps tend to accumulate population genetic differences faster than their figs, which initially decouples the speciation dynamics between the two interacting partners and breaks down their one-to-one matching. This intermediate phase is followed by genetic divergence of both partners, which may eventually restore the one-to-one matching among the fully formed species. Together, these findings integrate current knowledge on the mechanisms operating during different phases of the cospeciation process. They also reveal that the increasingly reported breakdowns in one-to-one matching may be an inherent part of the cospeciation process. Mechanistic understanding of this process is needed to explain how the extraordinary diversity of species, especially in the tropics, has emerged. Knowing which breakdowns in species interactions are a natural phase of cospeciation and which may endanger further generation of diversity seems critical in a constantly changing world.

Multiple genetic analyses to investigate the polymorphisms of Chinese Mongolian population with an efficient short tandem repeat panel

AimTo determine allele frequencies and forensic statistics of 22 autosomal short tandem repeat loci in Chinese Mongolian population.MethodsBlood specimens were collected from 134 unrelated healthy Mongolian individuals, and 22 short tandem repeat loci were co-amplified and genotyped. Allele frequencies and forensic parameters were calculated, and population genetic differences were analyzed among Mongolian population and other eight Chinese populations: Northern Han, Guangdong Han, Chengdu Han, Xinjiang Hui, Xinjiang Uygur, Hainan Li, Qinghai Tibetan, and Hainan Han.ResultsAll the loci were in the Hardy-Weinberg equilibrium, and after Bonferroni correction there was no linkage disequilibrium between them. The allele frequencies of these 22 loci were between 0.0037 and 0.3657. This panel had high discriminating power and genetic polymorphism in the Mongolian population, with combined power of discrimination of 0.999999999999999999999999998399 and combined probability of exclusion of 0.9999999999566925. Structure analysis showed no evidence that these nine Chinese populations had different component distribution. However, genetic distance analysis showed significant differences among them (P < 0.05).ConclusionThe combined application of these 22 loci could be useful for forensic purposes in the Mongolian population. Mongolian population had smaller genetic distances from the populations in northern China (Northern Han, Xinjiang Uygur, and Xinjiang Hui) than from the populations in Hainan province (Hainan Han and Hainan Li populations).

Genetic diversity and genetic structure of natural populations in an extremely narrowly distributed perennial species Glycine tabacina (Labill.) Benth. on the southeast islands in China

In China, Glycine tabacina (Labill.) Benth. is only distributed in the southeast coast and islands. In this study, 28 natural populations of G. tabacina species were sampled from 13 islands using 22 SSR markers. The Chinese G. tabacina was characterized by higher outcrossing rate and within-population genetic variation, extensive migration, greater population genetic differences and geographically weak-associated genetic differentiation, with higher level of heterogeneity within the natural populations along the southeast islands of China even though this species is a self-pollinating plant. The number of alleles per locus averaged 5.77 and ranged from 2 to 16. The expected heterozygosity (He) per locus averaged a value of 0.51, varying from 0.08 to 0.80. As an autogamous species, the Chinese G. tabacina unexpectedly showed a relatively high mean outcrossing rate in single locus (ts = 6.52%) and multilocus (tm = 6.75%), higher mean gene flow (Nm = 0.315), lower mean gene differentiation index (Gst = 0.436), and particularly, relatively lower among-population genetic variation (43.55%) and higher within-population genetic variation (49.66%) revealed by analysis of molecular variance. Spatial autocorrelation analysis revealed that populations within a radius of approximately 14.7 km would have a positive and significant genetic relationship to one another. However, the event of long-distance genetic background dispersal was revealed by individual assignment test and haplotype analysis (> 200 km dispersal was inferred, but > 56 km dispersal was observed). The north and middle-north islands of Fujian Province seemed to be the center of genetic diversity.