Sociogeographic correlates of typological variation in northwestern Bantu gender systems

This paper investigates the sociolinguistic factors that impact the typology and evolution of grammatical gender systems in northwestern Bantu, the most diverse area of the Bantu-speaking world. We base our analyses on a typological classification of 179 northwestern Bantu languages, focusing on various instances of semantic agreement and their role in the erosion of gender marking. In addition, we conduct in-depth analyses of the sociolinguistics and population history of the 17 languages of the sample with the most eroded gender systems. The sociohistorical factors identified to explain these highly eroded systems are then translated into a set of explanatory variables, which we use to conduct extensive quantitative analyses on the 179 language sample. These variables are population size, longitude, latitude, relationship with the Central African rainforest, and border with Ubangi/Central Sudanic languages. All these measures are relevant, with population size and bordering with Ubangi/Central Sudanic being the most robust factors in accounting for the distribution of gender restructuring. We conclude that fine-tuned variable design tailored to language and area-specific ecologies is crucial to the advancement of quantitative sociolinguistic typology.

Patterns in the Population History of Northern Eurasia from the Mesolithic to the Early Bronze Age, Based on Craniometry and Genetics

This study examines the craniometric differentiation of Northern Eurasian groups with reference to genetic and partly linguistic facts. Measurements of 66 series of male crania from that territory, dating to various periods from the Mesolithic to the Early Bronze Age, were subjected to statistical methods especially destined for detecting spatial patterns, specifi cally gradients. Using the nonmetric multidimensional scaling of the matrix of D2 distances corrected for sample size, a two-dimensional projection of group constellation was generated, and a minimum spanning tree, showing the shortest path between group centroids in the multivariate space, was constructed. East-west clines in Northern Eurasia, detected by both genetic and craniometric traits, likely indicate not so much gene fl ow as isolation by distance, resulting from an incomplete evolutionary divergence of various fi lial groups constituting the Boreal meta-population. The western fi lial component, which, in Siberia and Eastern Central Asia, is mostly represented by Afanasyevans, has evidently made little contribution to the genetic makeup of later populations. The eastern fi lial component, which had appeared in the Cis-Baikal region from across Lake Baikal no later than the Neolithic, admixed with the autochthonous Paleosiberian component. The latter’s principal marker—the ANE autosomal component—had been present in Siberia since the Upper Paleolithic. Likewise autochthonous were both Eurasian formations—Northern and Southern; statis tical analysis has made it possible to make these more inclusive, whereby the former has been expanded in the eastern direction to include the Kuznetsk Basin, and the latter westwards, to the Middle Irtysh. Nothing suggests that Eastern European groups had taken part in the origin of either the Northern Eurasian formation or the proto-Uralic groups.

Genomic Insights Into the Population History and Biological Adaptation of Southwestern Chinese Hmong–Mien People

Hmong–Mien (HM) -speaking populations, widely distributed in South China, the north of Thailand, Laos, and Vietnam, have experienced different settlement environments, dietary habits, and pathogenic exposure. However, their specific biological adaptation remained largely uncharacterized, which is important in the population evolutionary genetics and Trans-Omics for regional Precision Medicine. Besides, the origin and genetic diversity of HM people and their phylogenetic relationship with surrounding modern and ancient populations are also unknown. Here, we reported genome-wide SNPs in 52 representative Miao people and combined them with 144 HM people from 13 geographically representative populations to characterize the full genetic admixture and adaptive landscape of HM speakers. We found that obvious genetic substructures existed in geographically different HM populations; one localized in the HM clines, and others possessed affinity with Han Chinese. We also identified one new ancestral lineage specifically existed in HM people, which spatially distributed from Sichuan and Guizhou in the north to Thailand in the south. The sharing patterns of the newly identified homogenous ancestry component combined the estimated admixture times via the decay of linkage disequilibrium and haplotype sharing in GLOBETROTTER suggested that the modern HM-speaking populations originated from Southwest China and migrated southward in the historic period, which is consistent with the reconstructed phenomena of linguistic and archeological documents. Additionally, we identified specific adaptive signatures associated with several important human nervous system biological functions. Our pilot work emphasized the importance of anthropologically informed sampling and deeply genetic structure reconstruction via whole-genome sequencing in the next step in the deep Chinese Population Genomic Diversity Project (CPGDP), especially in the regions with rich ethnolinguistic diversity.

The Genetic Structure and East-West Population Admixture in Northwest China Inferred From Genome-Wide Array Genotyping

Northwest China is a contacting region for East and West Eurasia and an important center for investigating the migration and admixture history of human populations. However, the comprehensive genetic structure and admixture history of the Altaic speaking populations and Hui group in Northwest China were still not fully characterized due to insufficient sampling and the lack of genome-wide data. Thus, We genotyped genome-wide SNPs for 140 individuals from five Chinese Mongolic, Turkic speaking groups including Dongxiang, Bonan, Yugur, and Salar, as well as the Hui group. Analysis based on allele-sharing and haplotype-sharing were used to elucidate the population history of Northwest Chinese populations, including PCA, ADMIXTURE, pairwise Fst genetic distance, f-statistics, qpWave/qpAdm and ALDER, fineSTRUCTURE and GLOBETROTTER. We observed Dongxiang, Bonan, Yugur, Salar, and Hui people were admixed populations deriving ancestry from both East and West Eurasians, with the proportions of West Eurasian related contributions ranging from 9 to 15%. The genetic admixture was probably driven by male-biased migration- showing a higher frequency of West Eurasian related Y chromosomal lineages than that of mtDNA detected in Northwest China. ALDER-based admixture and haplotype-based GLOBETROTTER showed this observed West Eurasian admixture signal was introduced into East Eurasia approximately 700 ∼1,000 years ago. Generally, our findings provided supporting evidence that the flourish transcontinental communication between East and West Eurasia played a vital role in the genetic formation of northwest Chinese populations.

Domestication reshaped the genetic basis of inbreeding depression in a maize landrace compared to its wild relative, teosinte

Inbreeding depression is the reduction in fitness and vigor resulting from mating of close relatives observed in many plant and animal species. The extent to which the genetic load of mutations contributing to inbreeding depression is due to large-effect mutations versus variants with very small individual effects is unknown and may be affected by population history. We compared the effects of outcrossing and self-fertilization on 18 traits in a landrace population of maize, which underwent a population bottleneck during domestication, and a neighboring population of its wild relative teosinte. Inbreeding depression was greater in maize than teosinte for 15 of 18 traits, congruent with the greater segregating genetic load in the maize population that we predicted from sequence data. Parental breeding values were highly consistent between outcross and selfed offspring, indicating that additive effects determine most of the genetic value even in the presence of strong inbreeding depression. We developed a novel linkage scan to identify quantitative trait loci (QTL) representing large-effect rare variants carried by only a single parent, which were more important in teosinte than maize. Teosinte also carried more putative juvenile-acting lethal variants identified by segregation distortion. These results suggest a mixture of mostly polygenic, small-effect partially recessive effects in linkage disequilibrium underlying inbreeding depression, with an additional contribution from rare larger-effect variants that was more important in teosinte but depleted in maize following the domestication bottleneck. Purging associated with the maize domestication bottleneck may have selected against some large effect variants, but polygenic load is harder to purge and overall segregating mutational burden increased in maize compared to teosinte.

Insights into bear evolution from a Pleistocene polar bear genome

The polar bear (Ursus maritimus) has become a symbol of the threat to biodiversity from climate change. Understanding polar bear evolutionary history may provide insights into apex carnivore responses and prospects during periods of extreme environmental perturbations. In recent years, genomic studies have examined bear speciation and population history, including evidence for ancient admixture between polar bears and brown bears (Ursus arctos). Here, we extend our earlier studies of a 130,000-115,000-year-old polar bear from the Svalbard Archipelago using 10X coverage genome sequence and ten new genomes of polar and brown bears from contemporary zones of overlap in northern Alaska. We demonstrate a dramatic decline in effective population size for this ancient polar bear's lineage, followed by a modest increase just before its demise. A slightly higher genetic diversity in the ancient polar bear suggests a severe genetic erosion over a prolonged bottleneck in modern polar bears. Statistical fitting of data to alternative admixture graph scenarios favors at least one ancient introgression event from brown bears into the ancestor of polar bears, possibly dating back over 150,000 years. Gene flow was likely bidirectional, but allelic transfer from brown into polar bear is the strongest detected signal, which contrasts with other published works. These findings have implications for our understanding of climate change impacts: polar bears, a specialist Arctic lineage, may not only have undergone severe genetic bottlenecks, but also been the recipient of generalist, boreal genetic variants from brown bear during critical phases of Northern Hemisphere glacial oscillations.

Identification of a shared, common haplotype cosegregating with an SGCB c.544A>C mutation in Indian patients affected with sarcoglycanopathy

Background Sarcoglycanopathies (SG) is the most frequent form of autosomal recessive limb-girdle muscular dystrophies (LGMD) leading to progressive muscle wasting and weakness, predominantly characterized by limb-girdle weakness. LGMDR4 is caused by mutations in SGCB encoding for the beta-sarcoglycan proteins. In this study, we describe a shared, common haplotype cosegregating in 14 SG cases from 13 unrelated families with the likely pathogenic homozygous mutation c.544A>C (p.Thr182Pro) in SGCB. Methods The genotypes of five selected markers (rs10009426, rs6824707, rs2271046, rs35414474 and rs17611952) surrounding the c.544A>C (p.Thr182Pro) were extracted from the variant call format (VCF) generated from whole-exome sequencing (WES) of 14 cases and 14 related family members as controls. The linkage data file was constructed and linkage disequilibrium (LD) plots were generated using HaploView to visualize patterns of LD. Further, haplotype reconstructions based on the 6 markers were conducted using PLINK1.9. using the expectation-maximization (EM) algorithm, an iterative method to find maximum likelihood. Subsequently, the R programming language was used to determine and compare plots of the haplotype frequencies and percentages for both groups to infer the risk haplotypes. Results Four strong LD blocks were identified in control group: rs10009426 to rs6824707 (0.27 kb), rs6824707 to rs2271046 (41.6 kb), rs10009426 to rs2271046 (41.8 kb) and rs35414474 to rs17611952 (0.17 kb) which were absent in the case group. Similarly, a total of nine haplotypes were estimated in cases and controls of which haplotype H1= G, A, T, G, G, T showed significant statistical difference in the frequency between cases and controls. H1 is also observed to cosegregate with c.544A>C (p.Thr182Pro) in the pedigrees of all the cases. Conclusion The identification of c.544A>C (p.Thr182Pro) mutation in 14 cases from India indicates a probable event of founder effect. Further, the H1 haplotype, cosegregating with this mutation, convincingly sheds light on the recent developments in population genetics allowing insights into demographic and population history. This haplotype can also be used as a genetic marker to screen individuals with genetic susceptibility as carriers and provide genetically informed risk stratification and management in the prevention of SG.

Fine-scale population structure and demographic history of British Pakistanis

Previous genetic and public health research in the Pakistani population has focused on the role of consanguinity in increasing recessive disease risk, but little is known about its recent population history or the effects of endogamy. Here, we investigate fine-scale population structure, history and consanguinity patterns using genotype chip data from 2,200 British Pakistanis. We reveal strong recent population structure driven by the biraderi social stratification system. We find that all subgroups have had low recent effective population sizes (Ne), with some showing a decrease 15‒20 generations ago that has resulted in extensive identity-by-descent sharing and homozygosity, increasing the risk of recessive disorders. Our results from two orthogonal methods (one using machine learning and the other coalescent-based) suggest that the detailed reporting of parental relatedness for mothers in the cohort under-represents the true levels of consanguinity. These results demonstrate the impact of cultural practices on population structure and genomic diversity in Pakistanis, and have important implications for medical genetic studies.