Biology subjects

Fehn, A.-M.

Publications and source records attributed to Fehn, A.-M..

5 recordsLinked to original sources

bioRxiv2025

Post-admixture selection favours Duffy negativity in the Lower Okavango Basin

The FY*BES allele in the human Duffy blood group is nearly fixed across much of sub-Saharan Africa. Individuals homozygous for this allele (Duffy-negative) were considered resistant to red blood cell invasion by the malaria parasite Plasmodium vivax, restricting its distribution across the continent. However, as recent studies have demonstrated that P. vivax can infect Duffy-negative individuals and is widespread among African populations where FY*BES predominates, long-standing assumptions about the evolutionary relationship between Duffy negativity and parasite resistance should be re-evaluated across diverse geographic, ecological and epidemiological settings. Previous research investigating the role of natural selection in increasing the frequency of the FY*BES allele has primarily centered on admixed populations with African and non-African ancestries from regions with long-documented P. vivax transmission. Here, we focus on the Khwe foragers from the lower Okavango River Basin, where the parasite has only recently been reported. Using locus-specific statistics, simulations of neutral scenarios, and local ancestry inference, we found strong evidence for post-admixture selection promoting FY*BES introgression from Bantu-speaking populations into the Khwe. If P. vivax resistance indeed drove the rise in FY*BES allele frequency, our findings suggest that the parasite has been present in the region at least 500 to 1,000 years ago.

genetics↗

bioRxiv2023

Genome wide variation in the Angolan Namib desert reveals unique Pre-Bantu ancestry

The populations of the Angolan Namib Desert have been largely neglected in previous surveys of the genomic landscape of southern Africa. Although at present the Namib is culturally dominated by Southwest Bantu-speaking cattle-herders, the region exhibits an extraordinary ethnographic diversity which includes an array of semi-nomadic peoples whose subsistence strategies fall outside the traditional division between foraging and food production and can thus be referred to as "peripatetic". Among these small-scale populations are the last speakers of the Kwadi branch of the Khoe-Kwadi language family associated with the introduction of pastoralism into southern Africa (Kwepe), as well as a range of groups whose origins remain enigmatic (Kwisi, Twa and Tjimba). Using genome-wide data from 208 individuals belonging to nine ethnically diverse groups from the Angolan Namib and adjacent areas (Kwepe, Kwisi, Twa, Tjimba, !Xun, Kuvale, Himba, Nyaneka, Ovimbundu) in combination with published data from other regions of Africa, we reconstruct in detail the histories of contact emerging from pre-historic migrations to southern Africa and show that peripatetic groups from southwestern Angola stand out for exhibiting elevated levels of an unique, regionally-specific and highly divergent Pre-Bantu ancestry. These findings highlight the importance of the Namib for understanding the deep genetic structure of Africa.

genetics↗

bioRxiv2019

Mozambican genetic variation provides new insights into the Bantu expansion

The Bantu expansion, which started in West Central Africa around 5,000 BP, constitutes a major migratory movement involving the joint spread of peoples and languages across sub-Saharan Africa. Despite the rich linguistic and archaeological evidence available, the genetic relationships between different Bantu-speaking populations and the migratory routes they followed during various phases of the expansion remain poorly understood. Here, we analyze the genetic profiles of southwestern and southeastern Bantu-speaking peoples located at the edges of the Bantu expansion by generating genome-wide data for 200 individuals from 12 Mozambican and 3 Angolan populations using [~]1.9 million autosomal single nucleotide polymorphisms. Incorporating a wide range of available genetic data, our analyses confirm previous results favoring a \"late split\" between West and East Bantu speakers, following a joint passage through the rainforest. In addition, we find that Bantu speakers from eastern Africa display genetic substructure, with Mozambican populations forming a gradient of relatedness along a North-South cline stretching from the coastal border between Kenya and Tanzania to South Africa. This gradient is further associated with a southward increase in genetic homogeneity, and involved minimum admixture with resident populations. Together, our results provide the first genetic evidence in support of a rapid North-South dispersal of Bantu peoples along the Indian Ocean Coast, as inferred from the distribution and antiquity of Early Iron Age assemblages associated with the Kwale archaeological tradition.

genetics↗

bioRxiv2018

The role of matrilineality in shaping patterns of Y chromosome and mtDNA sequence variation in southwestern Angola

Southwestern Angola is a region characterized by contact between indigenous foragers and incoming food-producers, involving genetic and cultural exchanges between peoples speaking Kxa, Khoe-Kwadi and Bantu languages. Although present-day Bantu-speakers share a patrilocal residence pattern and matrilineal principle of clan and group membership, a highly stratified social setting divides dominant pastoralists from marginalized groups that subsist on alternative strategies and have previously been though to have pre-Bantu origins. Here, we compare new high-resolution sequence data from 2.3 Mb of the non-recombining Y chromosome (NRY) from 170 individuals with previously reported mitochondrial genomes (mtDNA), to investigate the population history of seven representative southwestern Angolan groups (Himba, Kuvale, Kwisi, Kwepe, Twa, Tjimba, !Xun) and to study the causes and consequences of sex-biased processes in their genetic variation. We found no clear link between the formerly Kwadi-speaking Kwepe and pre-Bantu eastern African migrants, and no pre-Bantu NRY lineages among Bantu-speaking groups, except for small amounts of \"Khoisan\" introgression. We therefore propose that irrespective of their subsistence strategies, all Bantu-speaking groups of the area share a male Bantu origin. Additionally, we show that in Bantu-speaking groups, the levels of among-group and between-group variation are higher for mtDNA than for NRY. These results, together with our previous demonstration that the matriclanic systems of southwestern Angolan Bantu groups are genealogically consistent, suggest that matrilineality strongly enhances both female population sizes and interpopulation mtDNA variation.

genetics↗

bioRxiv2017

The maternal genetic history of the Angolan Namib Desert: a key region for understanding the peopling of southern Africa

Southern Angola is a poorly studied region, inhabited by populations that have been associated with different migratory movements into southern Africa. Besides the long-standing presence of indigenous Kxa-speaking foragers and the more recent arrival of Bantu-speaking pastoralists, ethnographic and linguistic studies have suggested that other pre-Bantu communities were also present in the Namib desert, including peripatetic groups like the Kwepe (formerly Kwadi speakers), Twa and Kwisi. Here we evaluate previous peopling hypotheses by analyzing the relationships between seven groups from the Namib desert (Kuvale, Himba, Tjimba, Kwisi, Twa, Kwepe) and Kunene Province (!Xun), based on newly collected linguistic data and 295 complete mtDNA genomes. We found that: i) all groups from the Namib desert have genealogically-consistent matriclanic systems that had a strong impact on their maternal genetic structure by enhancing genetic drift and population differentiation; ii) the dominant pastoral groups represented by the Kuvale and Himba were part of a Bantu proto-population that also included the ancestors of present-day Damara and Herero peoples from Namibia; iii) Tjimba are closely related to the Himba; iv) the Kwepe, Twa and Kwisi have a divergent Bantu-related mtDNA profile and probably stem from a single population that does not show clear signs of being a pre-Bantu indigenous group. Taken together, our results suggest that the maternal genetic structure of the different groups from the Namib desert is largely derived from endogamous Bantu peoples, and that their social stratification and different subsistence patterns are not indicative of remnant groups, but reflect Bantu-internal variation and ethnogenesis.

genetics↗