Résumé
Understanding the processes by which species colonize and adapt to human
habitats is particularly important in the case of disease-vectoring
arthropods. The mosquito species Aedes aegypti, a major vector of dengue
and yellow fever viruses, probably originated as a wild, zoophilic species
in sub-Saharan Africa, where some populations still breed in tree holes in
forested habitats. Many populations of the species, however, have evolved
to thrive in human habitats and to bite humans. This includes some
populations within Africa as well as almost all those outside Africa. It
is not clear whether all domestic populations are genetically related and
represent a single ‘domestication’ event, or whether association with
human habitats has developed multiple times independently within the
species. To test the hypotheses above, we screened 24 worldwide population
samples of Ae. aegypti at 12 polymorphic microsatellite loci. We
identified two distinct genetic clusters: one included all domestic
populations outside of Africa and the other included both domestic and
forest populations within Africa. This suggests that human association in
Africa occurred independently from that in domestic populations across the
rest of the world. Additionally, measures of genetic diversity support Ae.
aegypti in Africa as the ancestral form of the species. Individuals from
domestic populations outside Africa can reliably be assigned back to their
population of origin, which will help determine the origins of new
introductions of Ae. aegypti.