Genome-wide Genetic Diversity Research Articles

Meiosis I causes a high spontaneous mutation rate in a multicellular red alga (Pyropia yezoensis) with a complex life cycle

Mutations are the origin of genetic diversity and are fundamental parameters needed to understand the molecular evolution of species. Estimations of mutation rates have been conducted for many diverse taxa, although rates in several major eukaryotic lineages remain unexplored. Here, the first estimation is reported of the spontaneous mutation rate for the multicellular eukaryote red alga, Pyropia yezoensis, which exhibits a complex life cycle. An estimated mutation rate of 2.97 × 10−8 (95 % CI: 2.16 × 10−8–3.99 × 10−8) per site per generation was generated for the primary life cycle, the sexual cycle, which is the highest sexual mutation rate among published sexual plants. Combined with tetrad analysis, meiosis I was identified as the primary period responsible for the high mutation rate during the complex life cycle of P. yezoensis. This result provides direct evidence for the “meiosis is mutagenic” hypothesis for multicellular organisms. The accurate estimate of the mutation rate of P. yezoensis also informs several immediate applications. Based on the above estimate, the effective population size (Ne) of P. yezoensis was estimated at about 19,000, with extensive haploid phases and asexual reproduction through monospores possibly leading to linked selection that may reduce the genome-wide genetic diversity of P. yezoensis and consequently influence Ne estimation. Lastly, P. yezoensis was estimated to have diverged from P. haitanensis about 4.2 Ma, representing a more recent date than estimates from fossil-calibrated phylogenies. These findings provide valuable new information for understanding the evolution of red algae, in addition to the underlying mechanism of mutations.

Comparative genomics and evolutionary analysis of dengue virus strains circulating in Pakistan.

Dengue fever virus (DENV) poses a significant public health risk in tropical and subtropical regions across the world. Although the dengue fever virus (DENV) exhibits significant genetic diversity and has the potential to evolve, there is a lack of comprehensive research on the comparative genomics and evolutionary dynamics of the virus in Pakistan. Phylogenetic analysis demonstrated the circulation of all four dengue virus serotypes (DENV-1, -2, -3, and -4) with prevalent genotypes III and V within DENV-1, cosmopolitan genotype within DENV-2, genotype III within DENV-3, and genotype I within DENV-4 during 2006-2014. Based on the complete envelope region, genome-wide residue signature and genetic diversity indicate that there is a high level of genetic diversity among DENV-1 strains, while DENV-3 strains exhibit the least genetic diversity. Comparative analysis of all four DENV serotypes revealed that certain codons in DENV-2 and -4 were subject to strong purifying selection, while a few codon sites in the envelope region showed evidence of positive selection. These findings provided valuable insights into the comparative genomics and evolutionary pattern of DENV strains reported from Pakistan. Whether those characteristics conferred a fitness advantage to DENV-1 genotypes within a specific geography and time interval warrants further investigations. The findings of the current study will contribute to tracking disease dynamics, understanding virus transmission and evolution, and formulating effective disease control strategies.

Demography and environment modulate the effects of genetic diversity on extinction risk in a butterfly metapopulation

Linking genetic diversity to extinction is a common goal in genomic studies. Recently, a debate has arisen regarding the importance of genetic variation in conservation as some studies have failed to find associations between genome-wide genetic diversity and extinction risk. However, only rarely are genetic diversity and fitness measured together in the wild, and typically demographic history and environment are ignored. It is therefore difficult to infer whether a lack of an association is real or obscured by confounding factors. To address these shortcomings, we analyzed genetic data from 7,501 individuals with extinction data from 279 meadows and mortality of 1,742 larval nests in a butterfly metapopulation. We found a strong negative association between genetic diversity and extinction when considering only heterozygosity in models. However, this association disappeared when accounting for ecological covariates, suggesting a confounding between demography and genetics and a more complex role for heterozygosity in extinction risk. Modeling interactions between heterozygosity and demographic variables revealed that associations between extinction and heterozygosity were context-dependent. For example, extinction declined with increasing heterozygosity in large, but not currently small populations, although negative associations between heterozygosity, extinction, and mortality were detected in small populations with a recent history of decline. We conclude that low genetic diversity is an important predictor of extinction, predicting >25% increase in extinction beyond ecological factors in certain contexts. These results highlight that inferences about the importance of genetic diversity for population viability should not rely on genomic data alone but require investments in obtaining demographic and environmental data from natural populations.

The Great Rift Valley is a more pronounced biogeographic barrier than the Blue Nile Valley for six Ethiopian Highland passerines in the eastern Afromontane biodiversity hotspot

ABSTRACT The Ethiopian Highlands are divided by lowland biogeographic barriers, including the Blue Nile Valley (BNV) and Great Rift Valley (GRV). We show that the GRV is a more pronounced phylogeographic break than the BNV for 6 focal passerines. Previous research suggests that the BNV greatly shaped phylogeographic patterns in relatively sedentary montane taxa such as frogs and rodents, whereas the GRV shaped phylogeographic patterns in volant taxa such as birds. However, no previous research simultaneously compares the impact of each valley on phylogeographic patterns in birds, and as these barriers vary in geographic extent and topography, the relative extent of their effects on gene flow is unclear. Using whole-genome resequencing, we quantified genetic variation in 6 montane forest passerines in the Ethiopian Highlands and found that their phylogeographic patterns varied, with general trends distinct from those of taxa that were previously studied across the same barriers. Genetic variation was assessed by estimating genome-wide genetic diversity (HO), demographic history, phylogeographic structure, and phylogeographic concordance among taxa. Population pairs flanking the GRV showed higher FST and more distinct population clusters in principal component analysis than those separated by the BNV. HO was broadly consistent across populations, excluding noticeable reductions in 2 populations (1 population each in 2 separate species). The overall phylogenetic signature and concordance across study taxa supported populations separated by the BNV as sister and populations southeast of the GRV as most distinct.

Whole-genome resequencing reveals genomic variation and dynamics in Ethiopian indigenous goats

Ethiopia has about 52 million indigenous goats with marked phenotypic variability, which is the outcome of natural and artificial selection. Here, we obtained whole-genome sequence data of three Ethiopian indigenous goat populations (Arab, Fellata, and Oromo) from northwestern Ethiopia and analyzed their genome-wide genetic diversity, population structure, and signatures of selection. We included genotype data from four other Ethiopian goat populations (Abergelle, Keffa, Gumuz, and Woyto-Guji) and goats from Asia; Europe; and eastern, southern, western, and northern Africa to investigate the genetic predisposition of the three Ethiopian populations and performed comparative genomic analysis. Genetic diversity analysis showed that Fellata goats exhibited the lowest heterozygosity values (Ho = 0.288 ± 0.005 and He = 0.334 ± 0.0001). The highest values were observed in Arab goats (Ho = 0.310 ± 0.010 and He = 0.347 ± 4.35e−05). A higher inbreeding coefficient (FROH = 0.137 ± 0.016) was recorded for Fellata goats than the 0.105 ± 0.030 recorded for Arab and the 0.112 ± 0.034 recorded for Oromo goats. This indicates that the Fellata goat population should be prioritized in future conservation activities. The three goat populations showed the majority (∼63%) of runs of homozygosity in the shorter (100–150 Kb) length category, illustrating ancient inbreeding and/or small founder effects. Population relationship and structure analysis separated the Ethiopian indigenous goats into two distinct genetic clusters lacking phylogeographic structure. Arab, Fellata, Oromo, Abergelle, and Keffa represented one genetic cluster. Gumuz and Woyto-Guji formed a separate cluster and shared a common genetic background with the Kenyan Boran goat. Genome-wide selection signature analysis identified nine strongest regions spanning 163 genes influencing adaptation to arid and semi-arid environments (HOXC12, HOXC13, HOXC4, HOXC6, and HOXC9, MAPK8IP2), immune response (IL18, TYK2, ICAM3, ADGRG1, and ADGRG3), and production and reproduction (RARG and DNMT1). Our results provide insights into a thorough understanding of genetic architecture underlying selection signatures in Ethiopian indigenous goats in a semi-arid tropical environment and deliver valuable information for goat genetic improvement, conservation strategy, genome-wide association study, and marker-assisted breeding.

Evaluating different approaches to integrate genome-wide genetic diversity in spatial conservation prioritization

Locations for new protected areas should be identified with consideration of intraspecific genetic diversity because genetic variation enhances the adaptability of species to novel environmental conditions. The process of siting new protected areas is called spatial conservation prioritization and is often formulated as a mathematical problem to be solved with the aid of computer software. Integrating multidimensional continuous metrics of genome-wide genetic diversity in spatial conservation prioritization involves significant challenges in terms of computation speed and memory requirements. In this study, we tested and compared several approaches to approximate the multidimensional continuous metrics of genetic diversity using multidimensional discrete genetic clusters or unidimensional discrete conservation features. To this end, we applied two tools for spatial conservation prioritization, raptr and prioritizr, to genomic datasets of two fish species (the white seabream Diplodus sargus and the red mullet Mullus surmuletus) sampled throughout most of their distribution range in the Mediterranean Sea. We found that most of the approximations tested either did not achieve all genetic conservation targets or resulted in excessively high conservation costs. Nonetheless, approaches based on multidimensional genetic clusters allowed generating prioritizations with relatively small gaps in genetic objectives at very high computation speed. This might be an interesting option for exploratory or interactive analyses such as those performed in workshop with stakeholders.

Genome-wide association study, population structure, and genetic diversity of the tea plant in Guizhou Plateau

BackgroundGuizhou Plateau, as one of the original centers of tea plant, has a profound multi-ethnic cultural heritage and abundant tea germplasm resources. However, the impact of indigenous community factors on the genetic diversity, population structure and geographical distribution of tea plant is still unclear.ResultsUsing the genotyping-by-sequencing (GBS) approach, we collected 415 tea plant accessions from the study sites, estimated genetic diversity, developed a core collection, and conducted a genome-wide association study (GWAS) based on 99,363 high-quality single-nucleotide polymorphisms (SNPs). A total of 415 tea accessions were clustered into six populations (GP01, GP02, GP03, GP04, GP05 and GP06), and the results showed that GP04 and GP05 had the highest and lowest genetic diversity (Pi = 0.214 and Pi = 0.145, respectively). Moreover, 136 tea accessions (33%) were selected to construct the core set that can represent the genetic diversity of the whole collection. By analyzing seven significant SNP markers associated with the traits such as the germination period of one bud and two leaves (OTL) and the germination period of one bud and three leaves (OtL), four candidate genes possibly related to OTL and OtL were identified.ConclusionsThis study revealed the impact of indigenous communities on the population structure of 415 tea accessions, indicating the importance of cultural practices for protection and utilization of tea plant genetic resources. Four potential candidate genes associated with the OTL and OtL of tea plant were also identified, which will facilitate genetic research, germplasm conservation, and breeding.

Genomic data reveal strong differentiation and reduced genetic diversity in island golden eagle populations

Abstract Understanding population structure and the extent and distribution of genetic diversity are recognized as central issues in endangered species research, with broad implications for effective conservation management. Advances in whole genome sequencing techniques provide greater resolution of genome-wide genetic diversity and inbreeding. Subspecies of golden eagles (Aquila chrysaetos) in Scotland (A. c. chrysaetos) and Japan (A. c. japonica) are endangered; it is therefore important to understand genetic diversity and inbreeding of these small island populations to increase the chances of conservation success. We investigated this using whole genome sequencing data from golden eagles in Scotland, continental Europe, Japan, and the USA. Following determination of population genetic structure, analysis of heterozygosity and nucleotide diversity revealed reduced levels of genetic diversity together with runs of homozygosity, suggesting evidence of inbreeding attributable to recent shared parental ancestry in the island populations. These results highlight the need to consider genetic reinforcement of small isolated golden eagle populations from neighbouring outbred populations, alongside existing efforts to boost population size through within-island conservation translocations and captive breeding programmes.

Phenotypic and genomic changes during Turnip mosaic virus adaptation to Arabidopsis thaliana mutants lacking epigenetic regulatory factors.

In this study, we investigated how an emerging RNA virus evolves, interacts, and adapts to populations of a novel host species with defects in epigenetically controlled plant defense mechanisms. Mutations in epigenetic regulatory pathways would exert different effects on defense-response genes but also induce large-scale alterations in cellular physiology and homeostasis. To test whether these effects condition the emergence and subsequent adaptation of a viral pathogen, we have evolved five independent lineages of a naive turnip mosaic virus (TuMV) strain in a set of Arabidopsis thaliana genotypes carrying mutations that influence important elements of two main epigenetic pathways and compare the results with those obtained for viral lineages evolved in wild-type plants. All evolved lineages showed adaptation to the lack of epigenetically regulated responses through significant increases in infectivity, virulence, and viral load although the magnitude of the improvements strongly depended on the plant genotype. In early passages, these traits evolved more rapidly, but the rate of evolution flattened out in later ones. Viral load was positively correlated with different measures of virulence, though the strength of the associations changed from the ancestral to the evolved viruses. High-throughput sequencing was used to evaluate the viral diversity of each lineage, as well as characterizing the nature of fixed mutations, evolutionary convergences, and potential targets of TuMV adaptation. Within each lineage, we observed a net increase in genome-wide genetic diversity, with some instances where nonsynonymous alleles experienced a transient rise in abundance before being displaced by the ancestral allele. In agreement with previous studies, viral VPg protein has been shown as a key player in the adaptation process, even though no obvious association between fixed alleles and host genotype was found.

Fish germ cell cryobanking and transplanting for conservation.

The unprecedented loss of global biodiversity is linked to multiple anthropogenic stressors. New conservation technologies are urgently needed to mitigate this loss. The rights, knowledge and perspectives of Indigenous peoples in biodiversity conservation-including the development and application of new technologies-are increasingly recognised. Advances in germplasm cryopreservation and germ cell transplantation (termed 'broodstock surrogacy') techniques offer exciting tools to preserve biodiversity, but their application has been underappreciated. Here, we use teleost fishes as an exemplar group to outline (1) the power of these techniques to preserve genome-wide genetic diversity, (2) the need to apply a conservation genomic lens when selecting individuals for germplasm cryobanking and broodstock surrogacy and (3) the value of considering the cultural significance of these genomic resources. We conclude by discussing the opportunities and challenges of these techniques for conserving biodiversity in threatened teleost fish and beyond.

Characterization of the genetic composition and establishment of a core collection for the INERA Robusta coffee (Coffea canephora) field genebank from the Democratic Republic of Congo

Cultivation of Robusta coffee is likely to gain importance because of its high disease resistance and climate envelope. Robusta coffee genetic resources conserved in field genebanks can play an important role to further improve its cupping quality and other agronomic traits, but such Coffea canephora collections are limited and still poorly characterized. In this study, we characterized the genetic composition of the historically important but until recently neglected INERA Coffee Collection in Yangambi (the Democratic Republic of Congo). We used GBS to discover genome-wide genetic diversity, created and validated a novel multiplex amplicon sequencing (HiPlex) screening assay to genetically screen 730 coffee shrubs of the Yangambi Coffee Collection, grouped clonal material and delineated 263 accessions with unique genetic fingerprints. Comparison to reference material of three genetic origins revealed that the majority of the Yangambi accessions were assigned a ‘Lula’ cultivar origin, four accessions were assigned to Congolese subgroup A and nine accessions were most closely related to local wild accessions. About one-quarter of the accessions was likely derived from hybridization between these groups, which could result from seed-based propagation of the collection, breeding efforts, or natural cross-pollination. Parental analyses discovered eight preferentially used accessions, which may correspond to historically selected founders, or direct descendants thereof, whose seed material was once widely used to establish coffee plantations. Finally, two core collections were proposed using the maximization strategy (CC-I; 100 accessions) and genetic distance method (CC-X; 10 accessions). Our study demonstrates a method for the genetic characterization of Robusta coffee collections in general and contributes to the re-evaluation and exploration of the Robusta coffee genetic resources in the Democratic Republic of the Congo in particular.

Harnessing genome-wide genetic diversity, population structure and linkage disequilibrium in Ethiopian durum wheat gene pool.

Yanyang Liu, Henan Academy of Agricultural Sciences (HNAAS), China; Landraces are an important genetic source for transferring valuable novel genes and alleles required to enhance genetic variation. Therefore, information on the gene pool's genetic diversity and population structure is essential for the conservation and sustainable use of durum wheat genetic resources. Hence, the aim of this study was to assess genetic diversity, population structure, and linkage disequilibrium, as well as to identify regions with selection signature. Five hundred (500) individuals representing 46 landraces, along with 28 cultivars were evaluated using the Illumina Infinium 25K wheat SNP array, resulting in 8,178 SNPs for further analysis. Gene diversity (GD) and the polymorphic information content (PIC) ranged from 0.13-0.50 and 0.12-0.38, with mean GD and PIC values of 0.34 and 0.27, respectively. Linkage disequilibrium (LD) revealed 353,600 pairs of significant SNPs at a cut-off (r2 > 0.20, P < 0.01), with an average r2 of 0.21 for marker pairs. The nucleotide diversity (π) and Tajima's D (TD) per chromosome for the populations ranged from 0.29-0.36 and 3.46-5.06, respectively, with genome level, mean π values of 0.33 and TD values of 4.43. Genomic scan using the Fst outlier test revealed 85 loci under selection signatures, with 65 loci under balancing selection and 17 under directional selection. Putative candidate genes co-localized with regions exhibiting strong selection signatures were associated with grain yield, plant height, host plant resistance to pathogens, heading date, grain quality, and phenolic content. The Bayesian Model (STRUCTURE) and distance-based (principal coordinate analysis, PCoA, and unweighted pair group method with arithmetic mean, UPGMA) methods grouped the genotypes into five subpopulations, where landraces from geographically non-adjoining environments were clustered in the same cluster. This research provides further insights into population structure and genetic relationships in a diverse set of durum wheat germplasm, which could be further used in wheat breeding programs to address production challenges sustainably.

Different waves of postglacial recolonisation and genomic structure of bank vole populations in NE Poland.

Previous studies indicated that in some species phylogeographic patterns obtained in the analysis of nuclear and mitochondrial DNA (mtDNA) markers can be different. Such mitonuclear discordance can have important evolutionary and ecological consequences. In the present study, we aimed to check whether there was any discordance between mtDNA and nuclear DNA in the bank vole population in the contact zone of its two mtDNA lineages. We analysed the population genetic structure of bank voles using genome-wide genetic data (SNPs) and diversity of sequenced heart transcriptomes obtained from selected individuals from three populations inhabiting areas outside the contact zone. The SNP genetic structure of the populations confirmed the presence of at least two genetic clusters, and such division was concordant with the patterns obtained in the analysis of other genetic markers and functional genes. However, genome-wide SNP analyses revealed the more detailed structure of the studied population, consistent with more than two bank vole recolonisation waves, as recognised previously in the study area. We did not find any significant differences between individuals representing two separate mtDNA lineages of the species in functional genes coding for protein-forming complexes, which are involved in the process of cell respiration in mitochondria. We concluded that the contemporary genetic structure of the populations and the width of the contact zone were shaped by climatic and environmental factors rather than by genetic barriers. The studied populations were likely isolated in separate Last Glacial Maximum refugia for insufficient amount of time to develop significant genetic differentiation.

Colonialism in South Africa leaves a lasting legacy of reduced genetic diversity in Cape buffalo.

The iconic Cape buffalo has experienced several documented population declines in recent history. These declines have been largely attributed to the late 19th century rinderpest pandemic. However, the effect of the rinderpest pandemic on their genetic diversity remains contentious, and other factors that have potentially affected this diversity include environmental changes during the Pleistocene, range expansions and recent human activity. Motivated by this, we present analyses of whole genome sequencing data from 59 individuals from across the Cape buffalo range to assess present-day levels of genome-wide genetic diversity and what factors have influenced these levels. We found that the Cape buffalo has high average heterozygosity overall (0.40%), with the two southernmost populations having significantly lower heterozygosity levels (0.33% and 0.29%) on par with that of the domesticated water buffalo (0.29%). Interestingly, we found that these lower levels are probably due to recent inbreeding (average fraction of runs of homozygosity 23.7% and 19.9%) rather than factors further back in time during the Pleistocene. Moreover, detailed investigations of recent demographic history show that events across the past three centuries were the main drivers of the exceptional loss of genetic diversity in the southernmost populations, coincident with the onset of colonialism in the southern extreme of the Cape buffalo range. Hence, our results add to the growing body of studies suggesting that multiple recent human-mediated impacts during the colonial period caused massive losses of large mammal abundance in southern Africa.

Whole genome sequencing revealed genetic diversity, population structure, and selective signature of Panou Tibetan sheep

BackgroundThe detection of selective traits in different populations can not only reveal current mechanisms of artificial selection for breeding, but also provide new insights into phenotypic variation in new varieties and the search for genes associated with important traits. Panou sheep is a cultivated breed of Tibetan sheep in China with stable genetic performance, consistent appearance and fast growth and development after decades of artificial selection and cultivation. Due to long-term adaptation to the high altitude, cold and hypoxic environment in the plateau area, they may have formed a unique gene pool that is different from other Tibetan sheep breeds. To explore the genetic resources of Panou sheep, we used next-generation sequencing technology for the first time to investigate the genome-wide population structure, genetic diversity, and candidate signatures of positive selection in Panou sheep.ResultsComparative genomic analysis with the closely related species Oula sheep (a native breed of Tibetan sheep in China) was used to screen the population selection signal of Panou sheep. Principal component analysis and neighbor joining tree showed that Panou sheep and Oula sheep had differences in population differentiation. Furthermore, analyses of population structure, they came from the same ancestor, and when K = 2, the two populations could be distinguished. Panou sheep exhibit genetic diversity comparable to Oula sheep, as shown by observed heterozygosity, expected heterozygosity and runs of homozygosity. Genome-wide scanning using the Fst and π ratio methods revealed a list of potentially selected related genes in Panou sheep compared to Oula sheep, including histone deacetylase 9 (HDAC9), protein tyrosine kinase 2 (PTK2), microphthalmia-related transcription factor (MITF), vesicular amine transporter 1 (VAT1), trichohyalin-like 1 (TCHHL1), amine oxidase, copper containing 3 (AOC3), interferon-inducible protein 35 (IFI35).ConclusionsThe results suggest that traits related to growth and development and plateau adaptation may be selection targets for the domestication and breeding improvement of Tibetan sheep. This study provides the fundamental footprints for Panou sheep breeding and management.

Genome-wide identification, characterization, and genetic diversity of CCR gene family in Dalbergia odorifera.

Lignin is a complex aromatic polymer plays major biological roles in maintaining the structure of plants and in defending them against biotic and abiotic stresses. Cinnamoyl-CoA reductase (CCR) is the first enzyme in the lignin-specific biosynthetic pathway, catalyzing the conversion of hydroxycinnamoyl-CoA into hydroxy cinnamaldehyde. Dalbergia odorifera T. Chen is a rare rosewood species for furniture, crafts and medicine. However, the CCR family genes in D. odorifera have not been identified, and their function in lignin biosynthesis remain uncertain. Here, a total of 24 genes, with their complete domains were identified. Detailed sequence characterization and multiple sequence alignment revealed that the DoCCR protein sequences were relatively conserved. They were divided into three subfamilies and were unevenly distributed on 10 chromosomes. Phylogenetic analysis showed that seven DoCCRs were grouped together with functionally characterized CCRs of dicotyledons involved in developmental lignification. Synteny analysis showed that segmental and tandem duplications were crucial in the expansion of CCR family in D. odorifera, and purifying selection emerged as the main force driving these genes evolution. Cis-acting elements in the putative promoter regions of DoCCRs were mainly associated with stress, light, hormones, and growth/development. Further, analysis of expression profiles from the RNA-seq data showed distinct expression patterns of DoCCRs among different tissues and organs, as well as in response to stem wounding. Additionally, 74 simple sequence repeats (SSRs) were identified within 19 DoCCRs, located in the intron or untranslated regions (UTRs), and mononucleotide predominated. A pair of primers with high polymorphism and good interspecific generality was successfully developed from these SSRs, and 7 alleles were amplified in 105 wild D. odorifera trees from 17 areas covering its whole native distribution. Overall, this study provides a basis for further functional dissection of CCR gene families, as well as breeding improvement for wood properties and stress resistance in D. odorifera.

Phylogeographic structure of Heteroplexis (Asteraceae), an endangered endemic genus in the limestone karst regions of southern China.

Though the karst regions in south and southwest China are plant diversity hotspots, our understanding of the phylogeography and evolutionary history of the plants there remains limited. The genus Heteroplexis (Asteraceae) is one of the typical representative plants isolated by karst habitat islands, and is also an endangered and endemic plant to China. In this study, species-level phylogeographic analysis of the genus Heteroplexis was conducted using restriction site-associated DNA sequencing (RADseq). The genetic structure showed a clear phylogeographic structure consistent with the current species boundaries in the H. microcephala, H. incana, H. vernonioides, H. sericophylla, and H. impressinervia. The significant global (R = 0.37, P < 0.01) and regional (R = 0.650.95, P < 0.05) isolation by distance (IBD) signals among species indicate strong geographic isolation in the karst mountains, which may result in chronically restricted gene flow and increased genetic drift and differentiation. Furthermore, the phylogeographic structure of Heteroplexis suggested a southward migration since the last glacial period. Demographic analysis revealed the karst mountains as a refuge for Heteroplexis species. Finally, both Treemix and ABBA-BABA statistic detected significant historical gene flow between species. Significant historical gene flow and long-term stability of effective population size (Ne) together explain the high genome-wide genetic diversity among species (π = 0.05370.0838). However, the recent collapse of Ne, widespread inbreeding within populations, and restricted contemporary gene flow suggest that Heteroplexis species are probably facing a high risk of genetic diversity loss. Our results help to understand the evolutionary history of karst plants and guide conservation.

Genome-Wide Genetic Diversity and Population Structure of Local Sudanese Sheep Populations Revealed by Whole-Genome Sequencing

Local Sudanese sheep populations inhabiting diverse environmental conditions and holding opposing morphologies provide opportunities for molecular-genetic research. Characterizing their genome is crucial for sustainable breeding improvement and targeting favorable genes in breeding programs. However, the genome of these sheep populations, which comprises several subtypes, remains uncharacterized using whole-genome sequence data. This study aimed to elucidate genome-wide genetic diversity and population structure of 11 local Sudanese sheep populations, namely, Hammari, Kabbashi, Meidobe, Ashgar, Dubasi, Watish, Bega, Naili, Fulani, Zagawi, and Garag. Ninety whole blood samples were collected, and we extracted DNA using a Qiagen DNeasy® extraction kit. We used the Illumina HiSeq 2000 platform to sequence all the DNA samples. We included whole-genome sequence data of three Ethiopian sheep (Doyogena, Kefis, and Gafera) and one Libyan sheep (Libyan Barbary) in the study to infer the genetic relationships of local Sudanese sheep populations from a continental perspective. A total of 44.8 million bi-allelic autosomal SNPs were detected; 28.5% and 63.3% occur in introns and intergenic regions, respectively. The mean genetic diversity ranged from 0.276 for Garag to 0.324 for Kabbashi sheep populations. The lowest FST estimates were observed between Kabbashi and Ashgar and the highest between Bega and Fulani local Sudanese sheep populations. The principal component and population structure analyses of the 11 local Sudanese sheep populations indicated three separate genetic groups categorized following their tail morphotype, geographical distribution, and population subtype. The thin-tailed local Sudanese sheep populations exhibited independent clustering from the fat-tailed Ethiopian and Libyan sheep. We also observed distinct clustering between the fat-tailed Ethiopian and Libyan sheep. The present study’s findings demonstrated the population structure and principal components related to tail morphotype, geographical distribution, and population subtype of local Sudanese sheep populations. A clear signature of admixture was observed among the studied local Sudanese sheep populations.

Relationship between genome-wide and MHC class I and II genetic diversity and complementarity in a nonhuman primate.

Although mate choice is expected to favor partners with advantageous genetic properties, the relative importance of genome‐wide characteristics, such as overall heterozygosity or kinship, versus specific loci, is unknown. To disentangle genome‐wide and locus‐specific targets of mate choice, we must first understand congruence in global and local variation within the same individual. This study compares genetic diversity, both absolute and relative to other individuals (i.e., complementarity), assessed across the genome to that found at the major histocompatibility complex (MHC), a hyper‐variable gene family integral to immune system function and implicated in mate choice across species. Using DNA from 22 captive olive baboons (Papio anubis), we conducted double digest restriction site‐associated DNA sequencing to estimate genome‐wide heterozygosity and kinship, and sequenced two class I and two class II MHC loci. We found that genome‐wide diversity was not associated with MHC diversity, and that diversity at class I MHC loci was not correlated with diversity at class II loci. Additionally, kinship was a significant predictor of the number of MHC alleles shared between dyads at class II loci. Our results provide further evidence of the strong selective pressures maintaining genetic diversity at the MHC in comparison to other randomly selected sites throughout the genome. Furthermore, our results indicate that class II MHC disassortative mate choice may mediate inbreeding avoidance in this population. Our study suggests that mate choice favoring genome‐wide genetic diversity is not always synonymous with mate choice favoring MHC diversity, and highlights the importance of controlling for kinship when investigating MHC‐associated mate choice.

Genome-Wide Population Structure Analysis and Genetic Diversity Detection of Four Chinese Indigenous Duck Breeds from Fujian Province.

Simple SummaryThe aim of this study was to conduct a genome-wide comparative analysis of four indigenous Chinese duck breeds (Jinding, Liancheng white, Putian black, and Shanma ducks) from Fujian Province, to understand their genetic diversity and population structure. Population parameters showed that the four indigenous breeds were separated groups. Five genomic regions are presented as hotspots of autozygosity among these indigenous duck breeds, with candidate genes involved in muscle growth, pigmentation, and neuroregulation. Genomic information may play a vital role in the improvement of conservation strategies.The assessment of population genetic structure is the basis for understanding the genetic information of indigenous breeds and is important for the protection and management of indigenous breeds. However, the population genetic differentiation of many local breeds still remains unclear. Here, we performed a genome-wide comparative analysis of Jinding, Liancheng white, Putian black, and Shanma ducks based on the genomic sequences using RAD sequencing to understand their population structure and genetic diversity. The population parameters showed that there were obvious genetic differences among the four indigenous breeds, which were separated groups. Among them, Liancheng white and Shanma ducks may come from the same ancestor because the phylogenetic tree forms three tree trunks. In addition, during the runs of homozygosity (ROH), we found that the average inbreeding coefficient of Liancheng white and Putian black ducks was the lowest and the highest, respectively. Five genomic regions were considered to be the hotspots of autozygosity among these indigenous duck breeds, and the candidate genes involved a variety of potential variations, such as muscle growth, pigmentation, and neuroregulation. These findings provide insights into the further improvement and conservation of Fujian duck breeds.