Biology subjects

Gerbault, P.

Publications and source records attributed to Gerbault, P..

3 recordsLinked to original sources

bioRxiv2026

Microbial community profiles of genital and non-genital skin lesions from Ghana

Skin ulcers, such as those observed in cases of the non-venereal disease yaws and the venereal disease syphilis, are traditionally diagnosed based on their anatomical location and visible appearance. Yet various evidence suggests that the pathogens that cause these ulcers may not be restricted to genital or non-genital body sites. We explored this by profiling the bacterial communities of genital and non-genital skin ulcers collected in Ghana using 16S rRNA gene amplicon sequencing. Swab samples were collected from 156 clinically diagnosed skin lesions (110 non-genital and 46 genital). The V1-V2 region of the 16S rRNA gene was sequenced to characterize bacterial communities. Microbial diversity, community composition, differential abundance, and associations between lesion diversity and common skin bacteria were analysed using bioinformatics and statistical methods. Following quality filtering, 135 samples were retained, revealing 23 bacterial phyla, 143 families, and 406 genera. Alpha diversity indicated similar bacterial richness and diversity in genital and non-genital skin lesions. Beta diversity analyses indicated differences between genital and non-genital lesions, accompanied by significant differences in within group dispersion. A log2 fold change analysis evidenced genital lesions were enriched in Gardnerella, whereas non-genital lesions showed more abundance of Staphylococcus, Streptococcus, Corynebacterium, Bradyrhizobium, and Pelomonas. Clinically important genera, including Treponema, Haemophilus, and Mycobacterium, were also detected, even in samples with low sequencing depths. Statistical modelling indicated that greater microbial diversity was associated with intermediate abundances of common skin taxa, particularly Corynebacteriaceae, Micrococcaceae, Cutibacterium, and Staphylococcaceae, thereby attesting the presence of polymicrobial communities in skin ulcers. Overall, genital and non-genital skin lesions showed similar microbial diversity but differed in composition. Our findings support the view of skin lesions as ecological niches containing diverse bacterial communities rather than being consistently dominated by a single bacterial taxon. They provide a basis for investigating possible polymicrobial interactions in skin ulcers.

microbiology↗

bioRxiv2026

Cultural norms of exogamy and mobility shape hunter-gatherer genetic evolution

Through a hunting and gathering lifestyle, humans have managed to thrive across all terrestrial ecosystems. A key adaptive feature enabling this ecological success is the ability of hunter-gatherer societies to maintain high levels of genetic diversity despite ecological and demographic shocks, but the mechanisms underlying this resilience are poorly understood. Here we integrate genomic, demographic, mobility and ethnographic data from two Central African hunter-gatherer populations to show that genetic diversity emerges from interacting effects of population size, mobility and cultural norms governing marriage. We first demonstrate direct selection against background homozygosity: even modest increases in runs of homozygosity, in the near absence of close-kin marriage, are associated with reduced reproductive success. Despite regional differences in effective population size, clustering of relatives, sedentism and exogamy rules, overall levels of homozygosity are similarly low in both populations. These shared genetic outcomes are achieved through distinct strategies: in one region, strict exogamy combined with high lifetime mobility limits local relatedness, whereas in the other, more relaxed exogamy norms are offset by increased male mate-search distances that reduce offspring homozygosity. Together, our results show that human populations flexibly adjust mobility and social norms to demographic constraints to preserve genetic diversity and avoid fitness costs, revealing culture as a central component of human adaptation.

genetics↗

bioRxiv2022

Hunter-gatherer oral microbiomes are shaped by contact network structure

Ancestral humans evolved a complex social structure still observed in extant hunter-gatherers. Here we investigate the effects of extensive sociality and mobility on the oral microbiome of 138 Agta hunter-gatherers from the Philippines. Comparisons of microbiome composition showed that the Agta are more similar to Central African Bayaka hunter-gatherers than to neighboring farmers. We also defined the Agta social microbiome as a set of 137 oral bacteria (only 7% of 1980 amplicon sequence variants) significantly influenced by social contact (quantified through wireless sensors of short-range interactions). We show that interaction networks covering large areas, and their strong links between close kin, spouses, and even unrelated friends, can significantly predict bacterial transmission networks across Agta camps. Finally, more central individuals to social networks are also bacterial supersharers. We conclude that hunter-gatherer social microbiomes, which are predominantly pathogenic, were shaped by evolutionary tradeoffs between extensive sociality and disease spread.

microbiology↗