Population genetic structure of the malaria vector Anopheles funestus, in a recently re-colonized area of the Senegal River basin and human-induced environmental changes
1 Département de Biologie animale Laboratoire d’écologie vectorielle et parasitaire, Université Cheikh Anta Diop de Dakar, Dakar-Fann, BP 5005, Sénégal
2 Unité d’entomologie médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, Dakar, BP 220, Sénégal
3 Institut de Recherche pour le Développement, Unité MIVEGEC (IRD 224-CNRS 5290-UM1-UM2), 34394, Montpellier Cedex 5, BP 64501, France
4 Institut de Recherche en Sciences de la Sante’-Direction Régionale de l’Ouest, Bobo Dioulasso, Burkina Faso
5 Department of Biological Sciences Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, 46556, USA
Parasites & Vectors 2012, 5:188 doi:10.1186/1756-3305-5-188Published: 5 September 2012
Anopheles funestus is one of the major malaria vectors in tropical Africa. Because of several cycles of drought events that occurred during the 1970s, this species had disappeared from many parts of sahelian Africa, including the Senegal River basin. However, this zone has been re-colonized during the last decade by An. funestus, following the implementation of two dams on the Senegal River. Previous studies in that area revealed heterogeneity at the biological and chromosomal level among these recent populations.
Here, we studied the genetic structure of the newly established mosquito populations using eleven microsatellite markers in four villages of the Senegal River basin and compared it to another An. funestus population located in the sudanian domain.
Our results presume Hardy Weinberg equilibrium in each An. funestus population, suggesting a situation of panmixia. Moreover, no signal from bottleneck or population expansion was detected across populations. The tests of genetic differentiation between sites revealed a slight but significant division into three distinct genetic entities. Genetic distance between populations from the Senegal River basin and sudanian domain was correlated to geographical distance. In contrast, sub-division into the Senegal River basin was not correlated to geographic distance, rather to local adaptation.
The high genetic diversity among populations from Senegal River basin coupled with no evidence of bottleneck and with a gene flow with southern population suggests that the re-colonization was likely carried out by a massive and repeated stepping-stone dispersion starting from the neighboring areas where An. funestus endured.