Population Structuring Research Articles

The Potential of Internal Migration to Shape Rural and Urban Populations Across Africa, Asia, and Latin America

AbstractSubnational divergence in the age and sex structures of populations can have far‐stretching consequences for development: from marriage markets to the potential for violence to economic growth. With urbanization and the demographic transition still underway, rural and urban populations continue to differ across low‐ and middle‐income countries. We examine the extent by which internal migration contributes to these differences, from 1970 to 2014 using estimates of migration between rural and urban sectors based on census data from 45 countries. We found that despite heavily delineated migration profiles by age and sex, internal migration does not alter sex and age structures of rural and urban populations. All the same, internal migration does increase urban growth in Asia and Latin America and the Caribbean. In contrast, in Africa, internal migration has little leverage with the urban transition. Across the continents, there is a potential for de‐urbanization, driven by a rural/urban gap in fertility. As such, the rural population may continue to constitute a significant proportion of national populations, necessitating critical investments to ensure they are not left behind.

Population structure of Desmophyllum pertusum found along the United States eastern continental margin

ObjectiveThe connectivity and genetic structuring of populations throughout a region influence a species’ resilience and probability of recovery from anthropogenic impacts. By gaining a comprehensive understanding of population connectivity, more effective management can be prioritized. To assess the connectivity and population genetic structure of a common cold-water coral species, Desmophyllum pertusum (Lophelia pertusa), we performed Restriction-site Associated DNA Sequencing (RADseq) on individuals from nine sites ranging from submarine canyons off New England to the southeastern coast of the United States (SEUS) and the Gulf of Mexico (GOM). Fifty-seven individuals and 3,180 single-nucleotide polymorphisms (SNPs) were used to assess genetic differentiation.ResultsHigh connectivity exists among populations along the SEUS, yet these populations were differentiated from those to the north off New England and in Norfolk Canyon along the North Atlantic coast of the United States, as well as those in the GOM. Interestingly, Norfolk Canyon, located just north of North Carolina, and GOM populations exhibited low levels of genetic differentiation, corroborating previous microsatellite analyses and signifying gene flow between these populations. Increasing sample sizes from existing populations and including additional sampling sites over a larger geographic range would help define potential source populations and reveal fine-scale connectivity patterns among D. pertusum populations.

Age structure of carp and catfish catch as a tool to assess ecological health of fished stocks from the Ganga River system with special reference to Mahseer Tor tor (Hamilton, 1822)

In the 20th centuary, the economically important carp species Labeo rohita, Tor tor, & Labeo calbasu and the catfishes Rita rita & Bagarius bagarius contributed substantially to the total fish catch from the Ganga River system in India. Samples were recorded between December 2003 and June 2004 from fish landing centers in the Ken, Paisuni, and Tons rivers for L. rohita, T. tor and L. calbasu. Rita rita and B. bagarius were sampled between September 2001 and September 2003 in the Ganga River system. The data were used to evaluate the growth and age structures of fish populations. Age classes varied 0+–5+ for L. rohita in the Ken & Paisuni rivers and 0+–8+ in the Tons River. For T. tor, the age classes varied 1+–6+ in the Ken & Paisuni rivers and 1+–8+ in the Tons. Age classes of L. calbasu varied 1+–6+ in the Ken River, 1+–5+ in the Paisuni River, and 1+–7+ in the Tons. In the Ganga River, age classes of R. rita & B. bagarius varied 0+–7+ and 0+–6+, respectively. The L. rohita, age pyramid showed a tendency for bell shape in Ken River, base tends to be broader through bell shape in Paisuni River, and bell-shaped age pyramid was slightly distorted in Tons River. In case of T. tor, tendency for bell shape in Ken River and bell-shaped age pyramid in Paisun River & Tons River were obtained. In case of L. calbasu, heavy bottom shaped age pyramid was recorded in Ken and Paisuni rivers, while base tends to be broader in the Tons River. Bell shaped age pyramid was recorded for B. bagarius in the Ganga River while heavy bottom shape for R. rita in the Ganga River. Overall, T. tor is facing heavy fishing pressure and also targeted fish species by fishermen from the Ganga River system.

Monitoring spatiotemporal patterns in the genetic diversity of a European butterfly species

Abstract The importance of genetic diversity has been recognised by the Convention on Biological Diversity but attempts at monitoring or improving the genetic diversity of populations have been minimal. Here, we investigate changes over time in the genetic diversity of a wild insect species, Maniola jurtina (Lepidoptera: Nymphalidae) and present a large‐scale investigation into contemporary spatial genetic diversity. Using microsatellite markers, we calculate multiple measures of genetic diversity and divergence for M. jurtina populations over 8 years in the UK and compare these findings with long‐term abundance trends. We also conduct a large‐scale spatial analysis into the genetic diversity and population structuring of M. jurtina across Europe. All UK populations sampled have high levels of gene flow and genetic diversity, with genetic diversity stable over time. Across Europe, we find some population structuring between populations in the UK and the European mainland, suggesting restricted geneflow between the two regions. The monitoring of a wild species' genetic diversity is an achievable aim, and one that could be carried out for many species, particularly Lepidoptera. Future approaches may aim to develop higher resolution genetic markers and cover a wider range of species. The use of abundance data offers additional insight, and we find that concurrent, dedicated genetic monitoring can provide effective tracking of biodiversity trends.

Normative computed tomography angiography values of the aortic root, aorta, and aortic arch in children.

Our study reports systolic and diastolic ECG-gated CTA Z-scores along with normative curves in relation to BSA for the aortic root, aorta, and aortic arch in children. • Normative data for intracardiac and extracardiac vascular structures in the pediatric population are available for echocardiography, cardiac MRI and non-ECG gated CTA. • Z-scores with standard deviations are commonly used in children, but SDs are not constant across body sizes due to heteroscedasticity. • Allometric exponent was derived for each parameter and the parameter/body surface area (BSA) was established. • This is the first ECG-gated CTA study to provide normative en face systolic, diastolic diameters and cross-sectional areas along with Z-scores and normative curves for the aortic root, aorta and aortic arch in children.

Influence of tool traverse speed on mechanical properties and fracture morphology of friction stir welded pure copper butt joints

The key goal of this research was to study the effect of the traverse speed of a tool on microstructural changes, mechanical properties and fracture morphology of pure copper butted weld joint by friction stir welding technique. In this study, other parameters like tool rotational speed (1000 rpm), axial force (4.2 kN), tilt angle (0˚) and tool offset (0 mm) were fixed. A cylindrical tool with a non-threaded tapered pin was used to fabricate the weld joints. All the weld joints produced by varying the traverse speeds (11, 20 and 24 mm min−1) were defect-free. It was noticed that the grains in the stir zone were tiny, well distributed and homogeneous at 24 mm min−1 owing to the adequate heat generation and complete intermixing of material in the stir zone. The utmost tensile strength of 187 MPa was achieved by the welded joint attained at 24 mm min−1. It was observed that a densely populated dimple structure enhances the joint ductility in the case of 24 mm min−1.

Studying Hierarchical Latent Structures in Heterogeneous Populations with Missing Information

Studying Hierarchical Latent Structures in Heterogeneous Populations with Missing Information

Population structure analysis of Phlebotomus papatasi populations using transcriptome microsatellites: possible implications for leishmaniasis control and vaccine development

BackgroundPhlebotomus papatasi is considered the primary vector of Leishmania major parasites that cause zoonotic cutaneous leishmaniasis (ZCL) in the Middle East and North Africa. Phlebotomus papatasi populations have been studied extensively, revealing the existence of different genetic populations and subpopulations over its large distribution range. Genetic diversity and population structure analysis using transcriptome microsatellite markers is important to uncover the vector distribution dynamics, essential for controlling ZCL in endemic areas.MethodsIn this study, we investigated the level of genetic variation using expressed sequence tag-derived simple sequence repeats (EST-SSRs) among field and colony P. papatasi samples collected from 25 different locations in 11 countries. A total of 302 P. papatasi sand fly individuals were analyzed, including at least 10 flies from each region.ResultsThe analysis revealed a high-level population structure expressed by five distinct populations A through E, with moderate genetic differentiation among all populations. These genetic differences in expressed genes may enable P. papatasi to adapt to different environmental conditions along its distribution range and likely affect dispersal.ConclusionsElucidating the population structuring of P. papatasi is essential to L. major containment efforts in endemic countries. Moreover, the level of genetic variation among these populations may improve our understanding of Leishmania–sand fly interactions and contribute to the efforts of vaccine development based on P. papatasi salivary proteins.Graphical

The genetic consequences of historic climate change on the contemporary population structure of a widespread temperate North American songbird

Studies of widely distributed species can inform our understanding of how past demographic events tied to historic glaciation and ongoing population genetic processes interact to shape contemporaneous patterns of biodiversity at a continental scale. In this study, we used whole-genome resequencing to investigate the current population structure and genetic signatures of past demographic events in the widespread migratory American goldfinch (Spinus tristis). Phylogenetic relationships inferred from whole mitochondrial genomes were poorly resolved. In contrast, a genome-wide panel of > 4.5 million single nucleotide polymorphisms (SNPs) strongly supported the existence of eastern and western populations separated by western mountain ranges and additional population structuring within the western clade. Demographic modeling estimated that the eastern and western populations diverged approximately one million years ago, and both populations experienced subsequent population bottlenecks during the last glacial period. Species distribution models showed a severe contraction of suitable habitat for the American goldfinch during this period, with predicted discontinuities that are consistent with multiple, isolated glacial refugia that coincide with present-day population structure. Low overall genetic differentiation between the eastern and western populations (FST ∼ 0.01) suggests ongoing gene flow accompanied divergence, and individuals with admixed genomic signatures were sampled along a potential contact zone. Nevertheless, outlier SNPs were identified near genes associated with feather color, song, and migratory behavior and provide strong candidates for further study of the mechanisms underlying reproductive isolation and speciation in birds.

Archaeogenomic analysis of Chesapeake Atlantic sturgeon illustrates shaping of its populations in recovery from severe overexploitation.

Atlantic sturgeon (Acipenser oxyrinchus ssp. oxyrinchus) has been a food resource in North America for millennia. However, industrial-scale fishing activities following the establishment of European colonies led to multiple collapses of sturgeon stocks, driving populations such as those in the Chesapeake area close to extinction. While recent conservation efforts have been successful in restoring census numbers, little is known regarding genomic consequences of the population bottleneck. Here, we characterize its effect on present-day population structuring and genomic diversity in James River populations. To establish a pre-collapse baseline, we collected genomic data from archaeological remains from Middle Woodland Maycock's Point (c. 200-900 CE), as well as Jamestown and Williamsburg colonial sites. Demographic analysis of recovered mitogenomes reveals a historical collapse in effective population size, also reflected in diminished present-day mitogenomic diversity and structure. We infer that James River fall- and spring-spawning populations likely took shape in recent years of population recovery, where genetic drift enhanced the degree of population structure. The mismatch of mitogenomic lineages to geographical-seasonal groupings implies that despite their homing instinct and differential adaptation manifested as season-specific behaviour, colonization of new rivers has been a key ecological strategy for Atlantic sturgeon over evolutionary timescales.

Seasonal distribution and population genetic structure of Psenopsis anomala (Japanese butterfish) inferred from otolith oxygen isotope ratios and mitochondrial DNA

Psenopsis anomala (Japanese butterfish) is a commercially important fish species with a wide distribution in the Northwest Pacific Ocean, but its catch in Taiwanese waters has been declining for decades. This study aims to elucidate the migration pattern and population structure of P. anomala by analyzing otolith δ18O values, mitochondrial COI and cyt b sequences, respectively. The results reveal a seasonal migration pattern between the northern South China Sea and the Yellow Sea. Analysis of the haplotype network reveals that most P. anomala collected from each location share the haplotypes Hap1 and Hap5, while each population also has its own unique haplotypes. Analysis of molecular variance reveals that the primary variation (92.98%) is observed among individuals within the populations. Fu's FS test conducted for all populations showed no significant differences, and the mismatch distribution aligns with recent population expansion. Both the maximum likelihood tree and the median-joining network show no geographic population structuring in P. anomala samples from Japan and Taiwan. The combined findings from otolith microchemistry and genetic analysis suggests that P. anomala distributed in east Asia shall be managed as a single stock.

Phenotypic divergence of Glossina morsitans (Diptera: Glossinidae) populations in Zambia: Application of landmark-based wing geometric morphometrics to discriminate population-level variation.

An important consequence of the discontinuous distribution of insect populations within their geographic range is phenotypic divergence. Detection of this divergence can be challenging when it occurs through subtle shifts in morphological traits with complex geometries, such as insect wing venation. Here, we used landmark-based wing geometric morphometrics to investigate the population-level phenotypic variation of the two subspecies of Glossina morsitans, G. m. centralis Machado and G. m. morsitans Westwood that occur in Zambia. Twelve homologous landmarks digitised on the right wings of 720 specimens collected from four and five sites (80 per site with 1:1 sex ratio) within the G. m. centralis and G. m. morsitans range respectively, were subjected to generalised Procrustes analysis to obtain wing centroid size (CS) and wing shape variables. Linear permutation models and redundancy analysis were then used to compare CS and wing shape between male and female G. morsitans, the two subspecies G. m. centralis and G. m. morsitans, the sexes of each subspecies and between sample locations within each subspecies range, respectively. Significant differences in CS and wing shape were observed between G. morsitans sexes, subspecies and sample locations within each subspecies range. A neighbour-joining cladogram derived from the analysis of Procrustes distances showed that tsetse within each subspecies range were highly divergent. We conclude that G. morsitans populations in Zambia exhibit significant population-level variation in fly size and wing shape which suggests high levels of population structuring. The main drivers of this structuring could be random genetic drift in G. m. centralis demes and local adaptation to environmental conditions in G. m. morsitans populations. We therefore recommend molecular studies to estimate the levels of gene flow between these populations and identify possible barriers to genetic flow.

Examining the Effects of Environment, Geography, and Elevation on Patterns of DNA Methylation Across Populations of Two Widespread Bumble Bee Species.

Understanding the myriad avenues through which spatial and environmental factors shape evolution is a major focus in biological research. From a molecular perspective, much work has been focused on genomic sequence variation; however, recently there has been increased interest in how epigenetic variation may be shaped by different variables across the landscape. DNA methylation has been of particular interest given that it is dynamic and can alter gene expression, potentially offering a path for a rapid response to environmental change. We utilized whole genome enzymatic methyl sequencing to evaluate the distribution of CpG methylation across the genome and to analyze patterns of spatial and environmental association in the methylomes of two broadly distributed montane bumble bees (Bombus vancouverensis Cresson and Bombus vosnesenskii Radoszkowski) across elevational gradients in the western US. Methylation patterns in both species are similar at the genomic scale with ∼1% of CpGs being methylated and most methylation being found in exons. At the landscape scale, neither species exhibited strong spatial or population structuring in patterns of methylation, although some weak relationships between methylation and distance or environmental variables were detected. Differential methylation analysis suggests a stronger environment association in B. vancouverensis given the larger number of differentially methylated CpG's compared to B. vosnesenskii. We also observed only a handful of genes with both differentially methylated CpGs and previously detected environmentally associated outlier SNPs. Overall results reveal a weak but present pattern in variation in methylation over the landscape in both species.

Geographic genetic variation in the Coral Hawkfish, Cirrhitichthys oxycephalus (Cirrhitidae), in relation to biogeographic barriers across the Tropical Indo-Pacific

The Tropical Indo-Pacific (TIP) includes about two thirds of the world’s tropical oceans and harbors an enormous number of marine species. The distributions of those species within the region is affected by habitat discontinuities and oceanographic features. As well as many smaller ones, the TIP contains seven large recognized biogeographic barriers that separate the Red Sea and Indian Ocean, the Indian from the Pacific Ocean, the central and eastern Pacific, the Hawaiian archipelago, the Marquesas and Easter Islands. We examined the genetic structuring of populations of Cirrhitichthys oxycephalus, a small cryptic species of reef fish, across its geographic range, which spans the longitudinal limits of the TIP. We assessed geographic variation in the mitochondrial cytb gene and the nuclear RAG1 gene, using 166 samples collected in 46 localities from the western to eastern edges of the TIP. Sequences from cytb show three well-structured groups that are separated by large genetic distances (1.58–2.96%): two in the Tropical Eastern Pacific (TEP), one at Clipperton Atoll another occupying the rest of that region and the third that ranges across the remainder of the TIP, from the central Pacific to the Red Sea and South Africa. These results indicate that the ~4,000 km wide Eastern Pacific Barrier between the central and eastern Pacific is an efficient barrier separating the two main groups. Further, the ~950 km of open ocean that isolates Clipperton Atoll from the rest of the TEP is also an effective barrier. Contrary to many other cases, various major and minor barriers from the Central Indo-Pacific to the Red Sea are not effective against dispersal by C. oxycephalus, although this species has not colonized the Hawiian islands and Easter Island. The nuclear gene partially supports the genetic structure evident in cytb, although all haplotypes are geographically mixed.

Measurement of the Tilt Angle of the Optic Disc Using Spectral-Domain Optical Coherence Tomography and Related Factors in Myopia.

This study presents a novel, three-dimensional method for measuring the tilt angle of the tilted optic disc (TOD) using spectral-domain optical coherence tomography (SD-OCT) and investigates the correlation between ocular-related parameters and TOD. We included the right eyes of 243 healthy young individuals, categorized by axial length. We measured the ovality index (OI) and dihedral angle (DA) using SD-OCT infrared ray fundus photographs and high-resolution cross-sectional images of the optic disc, respectively. The relationships between OI, DA, and ocular-related parameters were analyzed. Eyes in the longer axial length group exhibited a lower OI and a higher DA, along with thinner nasal and inferonasal circumpapillary retinal nerve fiber layer (cpRNFL) and thicker temporal and superotemporal cpRNFL. There was a significant relationship between DA and cpRNFL thickness. The new method utilizing DA to measure the tilt angle of TOD demonstrated high repeatability. We propose a novel, three-dimensional, and quantitative method for evaluating the tilt degree of TOD. A higher degree of myopia indicated a greater tilt angle of the TOD, and a greater TOD suggested additional changes in cpRNFL thickness. These findings should be considered when interpreting increased susceptibility and early assessment of glaucoma in myopia. DA could serve as a superior indicator for describing TOD morphology during eyeball elongation and evaluating its impact on related parameters of the optic disc and peripapillary structures in the myopic population.

Stands diversity and population structure of five ethnoveterinary woody species according to climatic zone and human disturbance in Benin (West Africa)

Farmers continue to use medicinal plants, alone or in combination with veterinary medicines, to treat animal diseases, especially in developing countries. The study aimed to determine the effect of climatic zone and anthropic disturbance level on the diversity of the natural stand and structures of Morinda lucida Benth, Spondias mombin L., Terminalia leiocarpa (DC.) Baill, Crossopteryx febrifuga (Afzel. ex G. Don) Benth, and Vitex doniana Sweet, five plant species often used in ethnoveterinary medicine in Benin. A floristic inventory was conducted in 206 plots of 0.15 ha each, distributed across 6 forests/hunting areas as well as surrounding fields and fallow land. The data were analyzed using R software by calculating the importance value index and the population structural parameters (density, basal area, mean height, etc.). The results showed that the floristic composition of the habitats of the five target species varied by climatic zone and disturbance level. Morinda lucida, S. mombin, and V. doniana were available in stands undergoing heavy disturbance in the Guinean zone, whereas T. leiocarpa and C. febrifuga were more available in the Sudano-Guinean and Sudanian zones. Values of structural parameters of these species were higher in the Guinean zone than in the other two zones. Furthermore, the results of the diameter structure showed C-values ranging from 1 to 3.6, suggesting the predominance of young individuals. This suggests strong human pressure on the adults of studied plants. These results should be used to contribute to the sustainable use of these species. Recommendations are made for the sustainable use of these five species, especially T. leiocarpa and C. febrifuga, which were heavily exploited given their low availability in stands under high human disturbance.

Analysing the pedigree to identify undesirable losses of genetic diversity and to prioritize management decisions in captive breeding: a case study.

When prevention of species extinction is the priority, captive breeding is a key component in conservation programmes, allowing the recording of pedigree information in studbooks. The genealogical information registered in Cuvier's gazelle studbook between 1975 and 2023 was analysed to (a) assess if the implemented mating policy was successful in preserving the genetic background of the founders (1 male:3 females) in the present population, and b) improve future management and breeding decisions. Although the maternal contribution of one founder female was lost and the mean inbreeding of the total live population was high (0.305 ± 0.095), the breeding policy applied produced better results than expected from a population starting from four founders. It was successful in keeping the individual increase in inbreeding low (0.047 ± 0.021), and, notably, the inbreeding tended to decrease during the last three decades of the breeding programme, ensuring the viability of this highly inbred population. Historical dissemination of individuals among the zoos of Europe and North America caused population structuring and genetic differentiation of the live North American population. However, it did not risk the viability of the captive population. The average relatedness coefficients allowed the identification of individuals with underrepresented genotypes, which is relevant to plan future mating guidelines to keep the founders' representation balanced in the next generations. This study highlights the importance of keeping long-term pedigree information to monitor changes in the genetic diversity of captive populations, which is crucial to implement optimal mating decisions and assuring their long-term viability within an ex situ conservation programme.

Genetic diversity and diversification patterns of puma (Puma concolor) populations in the southern end of the species distribution

The puma (Puma concolor Linnaeus, 1771) is the top predator with the widest distribution in America. Since the establishment of European settlers on the American continent, puma populations have experienced significant contractions and reductions in their original distribution. In Argentina, the management of the conflict between humans and pumas (direct persecution and habitat modification) focused on reduction or elimination methods, leading to a drastic contraction, even total eradication, of puma populations as seen in Patagonia and the eastern part of the country. Despite the lack of knowledge about puma population demographic trends, there are taxonomic issues that remain controversial and need to be resolved to implement appropriate management and conservation measures. Therefore, the aim of this study was to genetically characterize puma populations in the central-southern region of Argentina using two mitochondrial markers, evaluate their demographic history, compare our results at a macro-regional level, and discuss our findings in a conservation and management context. A total of 203 individuals were used, and a fragment of the control region and another of ND5 were sequenced. The genetic variability obtained was moderate. Substitution rates for each locus and the tMRCA were calculated from calibrated trees. In a concatenated tree, two main phylogenetic clades were identified (posterior probability = 1), although a reciprocal monophyly was not observed, with a divergence time of 228 thousand years and a 95% CI [117–363 thousand years]. When evaluating population structuring, three genetic clusters were found, one characteristic of the Patagonian region and the others in the central part of the country. Calculating the ФST values for pairs resulted in significant structuring between Patagonia and the rest of the populations, suggesting the arid diagonal as a possible barrier to gene flow. When evaluating the demographic history, neutrality tests would support a recent expansion in Patagonia. These findings are crucial in defining two distinct Management Units (MUs) in the southern part of puma distribution and providing valuable information for management and conservation measures for the species.

The influence of social and spatial processes on the epidemiology of environmentally transmitted pathogens in wildlife: implications for management.

Social and spatial structures of host populations play important roles in pathogen transmission. For environmentally transmitted pathogens, the host space use interacts with both the host social structure and the pathogen's environmental persistence (which determines the time-lag across which two hosts can transmit). Together, these factors shape the epidemiological dynamics of environmentally transmitted pathogens. While the importance of both social and spatial structures and environmental pathogen persistence has long been recognized in epidemiology, they are often considered separately. A better understanding of how these factors interact to determine disease dynamics is required for developing robust surveillance and management strategies. Here, we use a simple agent-based model where we vary host mobility (spatial), host gregariousness (social) and pathogen decay (environmental persistence), each from low to high levels to uncover how they affect epidemiological dynamics. By comparing epidemic peak, time to epidemic peak and final epidemic size, we show that longer infectious periods, higher group mobility, larger group size and longer pathogen persistence lead to larger, faster growing outbreaks, and explore how these processes interact to determine epidemiological outcomes such as the epidemic peak and the final epidemic size. We identify general principles that can be used for planning surveillance and control for wildlife host-pathogen systems with environmental transmission across a range of spatial behaviour, social structure and pathogen decay rates. This article is part of the theme issue 'The spatial-social interface: a theoretical and empirical integration'.

Genetic diversity of North African populations in the 17q21 genomic region.

The demographic history of human populations in North Africa has been characterized by complex migration processes that have determined the current genetic structure of these populations. We examined the autosomal markers of eight sampled populations in northern Africa (Tunisia and Libya) to explore their genetic structure and to place them in a global context. We genotyped a set of 30 autosomal single-nucleotide polymorphisms (SNPs) extending 9.5Mb and encompassing the 17q21 inversion region. Our data include 403 individuals from Tunisia and Libya. To put our populations in the global context, we analyzed our data in comparison with other populations, including those of the 1000 Genomes Project. To evaluate the data, we conducted genetic diversity, principal component, STRUCTURE, and haplotype analyses. The analysis of genetic composition revealed the genetic heterogeneity of North African populations. The principal component and STRUCTURE analyses converged and revealed the intermediate position of North Africans between Europeans and Asians. Haplotypic analysis demonstrated that the normal (H1) and inverted (H2) polymorphisms in the chromosome 17q21 region occur in North Africa at frequencies similar to those found in European and Southwest Asian populations. The results highlight the complex demographic history of North Africa, reflecting the influence of genetic flow from Europe and the Near East that dates to the prehistoric period. These gene flows added to demographic factors (inbreeding, endogamy), natural factors (topography, Sahara), and cultural factors that play a role in the emergence of the diverse and heterogeneous genetic structures of North African populations. This study contributes to a better understanding of the complex structure of North African populations.