Genetic population structure of Anopheles gambiae in Equatorial Guinea.
BACKGROUND
Patterns of genetic structure among mosquito vector populations in islands have received particular attention as these are considered potentially suitable sites for experimental trials on transgenic-based malaria control strategies. In this study, levels of genetic differentiation have been estimated between populations of Anopheles gambiae s.s. from the islands of Bioko and Annobón, and from continental Equatorial Guinea (EG) and Gabon.


METHODS
Genotyping of 11 microsatellite loci located in chromosome 3 was performed in three island samples (two in Bioko and one in Annobón) and three mainland samples (two in EG and one in Gabon). Four samples belonged to the M molecular form and two to the S-form. Microsatellite data was used to estimate genetic diversity parameters, perform demographic equilibrium tests and analyse population differentiation.


RESULTS
High levels of genetic differentiation were found between the more geographically remote island of Annobón and the continent, contrasting with the shallow differentiation between Bioko island, closest to mainland, and continental localities. In Bioko, differentiation between M and S forms was higher than that observed between island and mainland samples of the same molecular form.


CONCLUSIONS
The observed patterns of population structure seem to be governed by the presence of both physical (the ocean) and biological (the M-S form discontinuity) barriers to gene flow. The significant degree of genetic isolation between M and S forms detected by microsatellite loci located outside the "genomic islands" of speciation identified in A. gambiae s.s. further supports the hypothesis of on-going incipient speciation within this species. The implications of these findings regarding vector control strategies are discussed.
Moreno
Marta
M
Centro Nacional de Medicina Tropical, Instituto de Salud Carlos III, C/Sinesio Delgado 4, 28029 Madrid, Spain. martamor@isciii.es
Salgueiro
Patricia
P
Vicente
José Luis
JL
Cano
Jorge
J
Berzosa
Pedro J
PJ
de Lucio
Aida
A
Simard
Frederic
F
Caccone
Adalgisa
A
Do Rosario
Virgilio E
VE
Pinto
João
J
Benito
Agustín
A
D000818:Animals; D000852:Anopheles / Q000235:genetics*; D016703:Equatorial Guinea / Q000453:epidemiology; D014644:Genetic Variation; D005828:Genetics, Population; D007303:Insect Vectors / Q000235:genetics*; D008288:Malaria / Q000517:prevention & control*; D018895:Microsatellite Repeats / Q000235:genetics; D009032:Mosquito Control