Population genomic evidence of adaptive response during the invasion history of Plasmodium falciparum in the Americas
Résumé
Plasmodium falciparum, the most virulent agent of human malaria, spread from Africa to all
continents following the out-of-Africa human migrations. During the transatlantic slave trade
between the 16th and 19th centuries, it was introduced twice independently to the Americas
where it adapted to new environmental conditions (new human populations and mosquito
species). Here, we analyzed the genome-wide polymorphisms of 2,635 isolates across the
current P. falciparum distribution range in Africa, Asia, Oceania, and the Americas to
investigate its genetic structure, invasion history, and selective pressures associated with its
adaptation to the American environment. We confirmed that American populations originated
from Africa with at least two independent introductions that led to two genetically distinct
clusters, one in the North (Haiti and Columbia) and one in the South (French Guiana and
Brazil), and the admixed Peruvian group. Genome scans revealed recent and more ancient
signals of positive selection in the American populations. Particularly, we detected positive
selection signals in genes involved in interactions with host (human and mosquito) cells and
in genes involved in resistance to malaria drugs in both clusters. We found that some genes
were under selection in both clusters. Analyses suggested that for five genes, adaptive
introgression between clusters or selection on standing variation was at the origin of this
repeated evolution. This study provides new genetic evidence on P. falciparum colonization
history and on its local adaptation in the Americas.
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Licence : CC BY NC ND - Paternité - Pas d'utilisation commerciale - Pas de modification
Licence : CC BY NC ND - Paternité - Pas d'utilisation commerciale - Pas de modification