scholarly journals Unexpected high frequency of P46L TNFRSF1A allele in sub-Saharan West African populations

2004 ◽  
Vol 13 (4) ◽  
pp. 513-515 ◽  
Author(s):  
Dimitri Tchernitchko ◽  
Mihelaiti Chiminqgi ◽  
Frédéric Galactéros ◽  
Claude Préhu ◽  
Yvon Segbena ◽  
...  
2020 ◽  
Vol 6 (7) ◽  
pp. eaax5097 ◽  
Author(s):  
Arun Durvasula ◽  
Sriram Sankararaman

While introgression from Neanderthals and Denisovans has been documented in modern humans outside Africa, the contribution of archaic hominins to the genetic variation of present-day Africans remains poorly understood. We provide complementary lines of evidence for archaic introgression into four West African populations. Our analyses of site frequency spectra indicate that these populations derive 2 to 19% of their genetic ancestry from an archaic population that diverged before the split of Neanderthals and modern humans. Using a method that can identify segments of archaic ancestry without the need for reference archaic genomes, we built genome-wide maps of archaic ancestry in the Yoruba and the Mende populations. Analyses of these maps reveal segments of archaic ancestry at high frequency in these populations that represent potential targets of adaptive introgression. Our results reveal the substantial contribution of archaic ancestry in shaping the gene pool of present-day West African populations.


2018 ◽  
Author(s):  
Arun Durvasula ◽  
Sriram Sankararaman

AbstractWhile introgression from Neanderthals and Denisovans has been well-documented in modern humans outside Africa, the contribution of archaic hominins to the genetic variation of present-day Africans remains poorly understood. Using 405 whole-genome sequences from four sub-Saharan African populations, we provide complementary lines of evidence for archaic introgression into these populations. Our analyses of site frequency spectra indicate that these populations derive 2-19% of their genetic ancestry from an archaic population that diverged prior to the split of Neanderthals and modern humans. Using a method that can identify segments of archaic ancestry without the need for reference archaic genomes, we built genome-wide maps of archaic ancestry in the Yoruba and the Mende populations that recover about 482 and 502 megabases of archaic sequence, respectively. Analyses of these maps reveal segments of archaic ancestry at high frequency in these populations that represent potential targets of adaptive introgression. Our results reveal the substantial contribution of archaic ancestry in shaping the gene pool of present-day African populations.One sentence summaryMultiple present-day African populations inherited genes from an unknown archaic population that diverged before modern humans and Neanderthals split.


Diversity ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 428
Author(s):  
Martin Stervander ◽  
Bengt Hansson ◽  
Urban Olsson ◽  
Mark F. Hulme ◽  
Ulf Ottosson ◽  
...  

Larks constitute an avian family of exceptional cryptic diversity and striking examples of convergent evolution. Therefore, traditional morphology-based taxonomy has recurrently failed to reflect evolutionary relationships. While taxonomy ideally should integrate morphology, vocalizations, behaviour, ecology, and genetics, this can be challenging for groups that span several continents including areas that are difficult to access. Here, we combine morphometrics and mitochondrial DNA to evaluate the taxonomy of Calandrella larks, with particular focus on the African C. cinerea and the Asian C. acutirostris complexes. We describe a new range-restricted West African taxon, Calandrella cinerea rufipecta ssp. nov. (type locality: Jos, Plateau State, Nigeria), with an isolated relic population 3000 km from its closest relative in the Rift Valley. We performed molecular species delimitation, employing coalescence-based multi-rate Poisson Tree Processes (mPTP) on cytochrome b sequences across 52 currently recognized lark species, including multiple taxa currently treated as subspecies. Three species-level splits were inferred within the genus Calandrella and another 13 across other genera, primarily among fragmented sub-Saharan taxa and taxa distributed from Northwest Africa to Arabia or East Africa. Previously unknown divergences date back as far as to the Miocene, indicating the presence of currently unrecognized species. However, we stress that taxonomic decisions should not be based on single datasets, such as mitochondrial DNA, although analyses of mitochondrial DNA can be a good indicator of taxa in need of further integrative taxonomic assessment.


2005 ◽  
Vol 73 (2) ◽  
pp. 953-955 ◽  
Author(s):  
Karen Young ◽  
Angela Frodsham ◽  
Ogobara K. Doumbo ◽  
Sunetra Gupta ◽  
Amagana Dolo ◽  
...  

ABSTRACT Differences in allelic associations between populations continue to cause difficulties in the mapping and identification of susceptibility genes for complex polygenic diseases. Although well recognized, the basis of such interpopulation differences is poorly understood. We present an example of an inverse allelic association of an immune response genotype to an infectious disease in two neighboring West African populations. In this case, both the key environmental contributor, i.e., the malaria parasite, and a major biological mechanism are well defined. We show that this surprising result fits well with the predictions of a mathematical model describing the population genetics and dynamics of this interaction.


2010 ◽  
Vol 9 (11) ◽  
pp. 1658-1662 ◽  
Author(s):  
Odokuma ◽  
I E ◽  
Akpuaka ◽  
C F ◽  
Igbigbi ◽  
...  

2021 ◽  
Vol 1 (2) ◽  
pp. 34-41
Author(s):  
A Dieng ◽  
AD Faye ◽  
MM Ndiaye ◽  
G Diop ◽  
A Bouazé ◽  
...  

INTRODUCTION: Oral cavity cancers are now a public health problem according to WHO epidemiological data. There are several risk factors or factors associated with cancers of the oral cavity but they vary according to geographic regions. OBJECTIVE: The objective of this study was to identify factors associated with cancers of the oral cavity in Sub-Saharan African populations through a systematic literature review. METHODOLOGY: Using the data available for the period from January 1980 to December 2019, a synthesis of the literature was carried out. The literature localization strategy included an electronic search of the MEDLINE, EMBASE and GOOGLE SCHOLAR databases from 1980 to 2019 and a manual search of the list of references of articles identified by snowballing. The data were extracted independently by two researchers on an Excel© spreadsheet. Parameters collected from each study were author, country, type of study, period of study, size, age, gender, and factors studied. RESULTS: Out of 1,318 articles found, 24 were selected. The data contained 17,290 patients including 8,229 men, i.e. a male / female sex-ratio of 0.91. Factors studied were tobacco, alcohol, diet, infection, genetics and social factors. CONCLUSION: The results reported showed that several factors are associated with the occurrence of oral cavity cancers in Sub-Saharan Africa. There is a need to conduct further studies with more structured methodologies for more convincing results.


2018 ◽  
Author(s):  
Paloma Medina ◽  
Bryan Thornlow ◽  
Rasmus Nielsen ◽  
Russell Corbett-Detig

ABSTRACTAdmixture, the mixing of genetically distinct populations, is increasingly recognized as a fundamental biological process. One major goal of admixture analyses is to estimate the timing of admixture events. Whereas most methods today can only detect the most recent admixture event, here we present coalescent theory and associated software that can be used to estimate the timing of multiple admixture events in an admixed population. We extensively validate this approach and evaluate the conditions under which it can succesfully distinguish one from two-pulse admixture models. We apply our approach to real and simulated data of Drosophila melanogaster. We find evidence of a single very recent pulse of cosmopolitan ancestry contributing to African populations as well as evidence for more ancient admixture among genetically differentiated populations in sub-Saharan Africa. These results suggest our method can quantify complex admixture histories involving genetic material introduced by multiple discrete admixture pulses. The new method facilitates the exploration of admixture and its contribution to adaptation, ecological divergence, and speciation.


2020 ◽  
Vol 8 (2) ◽  
pp. 69-78
Author(s):  
Sodiq Olaiwola Jimoh ◽  
Felix Gbenga Olaifa

This study investigates the determinants of intra-regional trade in the Economic of West African States (ECOWAS) and the Community of Sahel-Saharan Sates (CEN-SAD) over the period of 1995-2018.The study employs the modified Poisson models, which captures the source of zero counts. Data on the real exchange rate, population, and gross domestic product were sourced from World Bank Development Indicators. Import flow, time of import, and time of export were computed from WITS (COMTRADE). Further, the study obtained data on voice and account, law and order, government effect, regulatory quality, reduction in political violence, control of corruption from World Wide Governance indicator. The results of the study indicated that imports within ECOWAS are driven by one governance variable or the other either in the importing countries or the partner countries. Besides, trade facilitation is a binding constraint to imports, while population and GDP are important drivers of intra-ECOWAS trade. For CEN-SAD, it is evident that the gravity variables are responsible for imports, whereas governance variables have no significant effect on imports. The implication of these results is that authorities in ECOWAS and CEN-SAD should strengthen governance institutions as doing so will boost trade within the region. Also, it is necessary for government, particularly in CEN-SAD, to come up with policies that will allow for accountability and transparency.


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