Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Elife e11473 [14 p.] AFRIQUE DE L'OUEST CAMEROUN GUINEE COTE D'IVOIRE 2016 fdi:010066155 ENG Elife 2050-084X ISI:000369059800001 10.7554/eLife.11473 https://www.documentation.ird.fr/hor/fdi:010066155 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers16-02/010066155.pdf 5 Horizon (IRD) Evolutionary theory predicts that the lack of recombination and chromosomal re assortment in strictly asexual organisms results in homologous chromosomes irreversibly accumulating mutations and thus evolving independently of each other, a phenomenon termed the Meselson effect. We apply a population genomics approach to examine this effect in an important human pathogen, Trypanosoma brucei gambiense. We determine that T.b. gambiense is evolving strictly asexually and is derived from a single progenitor, which emerged within the last 10,000 years. We demonstrate the Meselson effect for the first time at the genome-wide level in any organism and show large regions of loss of heterozygosity, which we hypothesise to be a short-term compensatory mechanism for counteracting deleterious mutations. Our study sheds new light on the genomic and evolutionary consequences of strict asexuality, which this pathogen uses as it exploits a new biological niche, the human population. 052 ; 020 Burkina Faso / Côte d'ivoire / Guinée