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Genetic population structure of Anopheles gambiae in Equatorial Guinea.

Moreno M, Salgueiro P, Vicente JL, Cano J, Berzosa PJ, de Lucio A, Simard F, Caccone A, Do Rosario VE, Pinto J, Benito A - Malar. J. (2007)

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centro Nacional de Medicina Tropical, Instituto de Salud Carlos III, C/Sinesio Delgado 4, 28029 Madrid, Spain. martamor@isciii.es

ABSTRACT

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.

Conclusion: 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.

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Related in: MedlinePlus

Bayesian cluster analysis using STRUCTURE. A: estimates of ΔK, based on the second order rate of change of the likelihood function with respect to K, to determine the most likely number of clusters (K) in the data set. In this case K = 3. B: graphical representation of the data set for the most likely K = 3, where each colour corresponds to a suggested cluster and each individual is represented by a vertical bar. The numbers in the X-axis correspond to a specific sample: 1- Annobón, 2- Bata, 3- Malabo, 4- Ngonamanga, 5- Sácriba and 6- Libreville. The Y-axis represents the probability of assignment of an individual to each cluster.
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Figure 2: Bayesian cluster analysis using STRUCTURE. A: estimates of ΔK, based on the second order rate of change of the likelihood function with respect to K, to determine the most likely number of clusters (K) in the data set. In this case K = 3. B: graphical representation of the data set for the most likely K = 3, where each colour corresponds to a suggested cluster and each individual is represented by a vertical bar. The numbers in the X-axis correspond to a specific sample: 1- Annobón, 2- Bata, 3- Malabo, 4- Ngonamanga, 5- Sácriba and 6- Libreville. The Y-axis represents the probability of assignment of an individual to each cluster.

Mentions: Bayesian cluster analysis performed with STRUCTURE [45] showed that the most likely K value identified was K = 3 (Figure 2a). This corresponds to three distinct genetic clusters (Figure 2b): (1) M-form A. gambiae s.s. from Annobón Island; (2) M-form samples from Bioko island (Malabo) and the mainland (Bata and Ngonamanga); (3) S-form samples from Bioko island (Sácriba) and the mainland (Libreville).


Genetic population structure of Anopheles gambiae in Equatorial Guinea.

Moreno M, Salgueiro P, Vicente JL, Cano J, Berzosa PJ, de Lucio A, Simard F, Caccone A, Do Rosario VE, Pinto J, Benito A - Malar. J. (2007)

Bayesian cluster analysis using STRUCTURE. A: estimates of ΔK, based on the second order rate of change of the likelihood function with respect to K, to determine the most likely number of clusters (K) in the data set. In this case K = 3. B: graphical representation of the data set for the most likely K = 3, where each colour corresponds to a suggested cluster and each individual is represented by a vertical bar. The numbers in the X-axis correspond to a specific sample: 1- Annobón, 2- Bata, 3- Malabo, 4- Ngonamanga, 5- Sácriba and 6- Libreville. The Y-axis represents the probability of assignment of an individual to each cluster.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2100067&req=5

Figure 2: Bayesian cluster analysis using STRUCTURE. A: estimates of ΔK, based on the second order rate of change of the likelihood function with respect to K, to determine the most likely number of clusters (K) in the data set. In this case K = 3. B: graphical representation of the data set for the most likely K = 3, where each colour corresponds to a suggested cluster and each individual is represented by a vertical bar. The numbers in the X-axis correspond to a specific sample: 1- Annobón, 2- Bata, 3- Malabo, 4- Ngonamanga, 5- Sácriba and 6- Libreville. The Y-axis represents the probability of assignment of an individual to each cluster.
Mentions: Bayesian cluster analysis performed with STRUCTURE [45] showed that the most likely K value identified was K = 3 (Figure 2a). This corresponds to three distinct genetic clusters (Figure 2b): (1) M-form A. gambiae s.s. from Annobón Island; (2) M-form samples from Bioko island (Malabo) and the mainland (Bata and Ngonamanga); (3) S-form samples from Bioko island (Sácriba) and the mainland (Libreville).

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centro Nacional de Medicina Tropical, Instituto de Salud Carlos III, C/Sinesio Delgado 4, 28029 Madrid, Spain. martamor@isciii.es

ABSTRACT

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.

Conclusion: 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.

Show MeSH
Related in: MedlinePlus