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

Badara Samb (1, 2) , Ibrahima Dia (2) , Lassana Konate (1) , Diego Ayala (3, 4) , Didier Fontenille (5) , Anna Cohuet (3, 6)

1 UCAD - Université Cheikh Anta Diop de Dakar [Sénégal]
2 UEM - Unité d'Entomologie Médicale [Dakar]
3 MIVEGEC - Maladies infectieuses et vecteurs : écologie, génétique, évolution et contrôle
4 UND - University of Notre Dame [Indiana]
5 MIVEGEC-DEEVA - Diversity, ecology, evolution & Adaptation of arthropod vectors
6 INSSA - Institut de Recherche en Sciences de la Santé Bobo Dioulasso

Background: 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. Methods: 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. Results: 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, subdivision into the Senegal River basin was not correlated to geographic distance, rather to local adaptation. Conclusions: 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.

Mots clés: Anopheles funestus; Re-emergent population; Population structure; Microsatellites; Senegal river basin

Domaines: Génétique animale; Génétique des populations [q-bio.PE]

Badara Samb, Ibrahima Dia, Lassana Konate, Diego Ayala, Didier Fontenille, et al.. 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. Parasites & Vectors, 2012, 5, pp.188. ⟨10.1186/1756-3305-5-188⟩. ⟨hal-03059005⟩