ResearchPopulation genetic structure of the malaria vector Anopheles nili in sub-Saharan Africa (original) (raw)
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Population genetic structure of the malaria vector Anopheles nili in sub-Saharan Africa
Malaria Journal, 2010
Background Anopheles nili is a widespread efficient vector of human malaria parasites in the humid savannas and forested areas of sub-Saharan Africa. Understanding An. nili population structure and gene flow patterns could be useful for the development of locally-adapted vector control measures. Methods Polymorphism at eleven recently developed microsatelitte markers, and sequence variation in four genes within the 28s rDNA subunit (ITS2 and D3) and mtDNA (COII and ND4) were assessed to explore the level of genetic variability and differentiation among nine populations of An. nili from Senegal, Ivory Coast, Burkina Faso, Nigeria, Cameroon and the Democratic Republic of Congo (DRC). Results All microsatellite loci successfully amplified in all populations, showing high and very similar levels of genetic diversity in populations from West Africa and Cameroon (mean Rs = 8.10-8.88, mean He = 0.805-0.849) and much lower diversity in the Kenge population from DRC (mean Rs = 5.43, mean He = 0.594). Bayesian clustering analysis of microsatellite allelic frequencies revealed two main genetic clusters in the dataset. The first one included only the Kenge population and the second grouped together all other populations. High Fst estimates based on microsatellites (Fst > 0.118, P < 0.001) were observed in all comparisons between Kenge and all other populations. By contrast, low Fst estimates (Fst < 0.022, P < 0.05) were observed between populations within the second cluster. The correlation between genetic and geographic distances was weak and possibly obscured by demographic instability. Sequence variation in mtDNA genes matched these results, whereas low polymorphism in rDNA genes prevented detection of any population substructure at this geographical scale. Conclusion Overall, high genetic homogeneity of the An. nili gene pool was found across its distribution range in West and Central Africa, although demographic events probably resulted in a higher level of genetic isolation in the marginal population of Kenge (DRC). The role of the equatorial forest block as a barrier to gene flow and the implication of such findings for vector control are discussed.
Acta Tropica, 2007
We used recently developed microsatellite DNA markers to explore the population genetic structure of the malaria vector, Anopheles moucheti. Polymorphism at 10 loci was examined to assess level of genetic differentiation between four A. moucheti populations from South Cameroon situated 65-400 km apart. All microsatellite loci were highly polymorphic with a number of distinct alleles per locus ranging from 9 to 17. F st estimates ranging from 0.0094 to 0.0275 (P < 0.001) were recorded. These results suggest a very low level of genetic differentiation between A. moucheti populations. The recently available microsatellite loci revealed useful markers to assess genetic differentiation between geographical populations of A. moucheti in Cameroon.
PLoS ONE, 2013
Background: The Anopheles nili group of mosquitoes includes important vectors of human malaria in equatorial forest and humid savannah regions of sub-Saharan Africa. However, it remains largely understudied, and data on its populations' bionomics and genetic structure are crucially lacking. Here, we used a combination of nuclear (i.e. microsatellite and ribosomal DNA) and mitochondrial DNA markers to explore and compare the level of genetic polymorphism and divergence among populations and species of the group in the savannah and forested areas of Cameroon, Central Africa.
Population genetics of Anopheles funestus, the African malaria vector, Kenya
Parasites & Vectors
Background: Anopheles funestus is among the major malaria vectors in Kenya and sub-Saharan Africa and has been recently implicated in persistent malaria transmission. However, its ecology and genetic diversity remain poorly understood in Kenya. Methods: Using 16 microsatellite loci, we examined the genetic structure of An. funestus sampled from 11 locations (n = 426 individuals) across a wide geographical range in Kenya spanning coastal, western and Rift Valley areas. Results: Kenyan An. funestus resolved as three genetically distinct clusters. The largest cluster (FUN1) broadly included samples from western and Rift Valley areas of Kenya with two clusters identified from coastal Kenya (FUN2 and FUN3), not previously reported. Geographical distance had no effect on population differentiation of An. funestus. We found a significant variation in the mean Plasmodium infectivity between the clusters (χ 2 = 12.1, df = 2, P = 0.002) and proportional to the malaria prevalence in the different risk zones of Kenya. Notably, there was variation in estimated effective population sizes between the clusters, suggesting possible differential impact of anti-vector interventions in represented areas. Conclusions: Heterogeneity among Kenyan populations of An. funestus will impact malaria vector control with practical implications for the development of gene-drive technologies. The difference in Plasmodium infectivity and effective population size between the clusters could suggest potential variation in phenotypic characteristics relating to competence or insecticide resistance. This is worth examining in future studies.
Rangewide population genetic structure of the African malaria vector Anopheles funestus
Molecular Ecology, 2005
Anopheles funestus is a primary vector of malaria in Africa south of the Sahara. We assessed its rangewide population genetic structure based on samples from 11 countries, using 10 physically mapped microsatellite loci, two per autosome arm and the X ( N = 548), and 834 bp of the mitochondrial ND5 gene ( N = 470). On the basis of microsatellite allele frequencies, we found three subdivisions: eastern (coastal Tanzania, Malawi, Mozambique and Madagascar), western (Burkina Faso, Mali, Nigeria and western Kenya), and central (Gabon, coastal Angola). A. funestus from the southwest of Uganda had affinities to all three subdivisions. Mitochondrial DNA (mtDNA) corroborated this structure, although mtDNA gene trees showed less resolution. The eastern subdivision had significantly lower diversity, similar to the pattern found in the codistributed malaria vector Anopheles gambiae . This suggests that both species have responded to common geographic and/or climatic constraints. The western division showed signatures of population expansion encompassing Kenya west of the Rift Valley through Burkina Faso and Mali. This pattern also bears similarity to A. gambiae , and may reflect a common response to expanding human populations following the development of agriculture. Due to the presumed recent population expansion, the correlation between genetic and geographic distance was weak. Mitochondrial DNA revealed further cryptic subdivision in A. funestus , not detected in the nuclear genome. Mozambique and Madagascar samples contained two mtDNA lineages, designated clade I and clade II, that were separated by two fixed differences and an average of 2% divergence, which implies that they have evolved independently for ∼ ∼ ∼ ∼ 1 million years. Clade I was found in all 11 locations, whereas clade II was sampled only on Madagascar and Mozambique. We suggest that the latter clade may represent mtDNA capture by A. funestus , resulting from historical gene flow either among previously isolated and divergent populations or with a related species.
Journal of the American Mosquito Control Association, 1998
The potential of microsatellites as population genetic markers in the malarial vectors Anopheles gambiae and Anopheles arabiensis was assessed using 4 loci. Substantial genetic divergence was found not only between these species but also between the Mopti and Forest chromosomal forms of An. gambiae, demonstrating that microsatellites do have the power to detect barriers to gene flow in these mosquitoes. However, application and interpretation of microsatellites was not necessarily straightforward. Despite the use of semiautomated fluorescent technology that enabled fragment sizes to be determined precisely, some difficulty was encountered in allele classification. Sequence analysis revealed insertions/deletions and base changes in the flanking regions of the microsatellite as the probable cause of this problem. The implications of this and other potential pitfalls in the use of microsatellites to study vector populations are discussed.
Heredity, 2003
Islands are choice settings for experimental studies of vector control strategies based on transgenic insects. Before considering this approach, knowledge of the population structure of the vector is essential. Genetic variation at 12 microsatellite loci was therefore studied in samples of the malaria vector Anopheles gambiae s.s., collected from six localities of Sã o Tomé island (West Africa). The objectives were (i) to assess the demographic stability and effective population size of A. gambiae from these sites, (ii) to determine population differentiation and (iii) to relate the observed patterns of population structure with geographic, ecological and historical aspects of the vector on the island.
Genetic Structure of a Local Population of the Anopheles gambiae Complex in Burkina Faso
PLOS ONE, 2016
Members of the Anopheles gambiae species complex are primary vectors of human malaria in Africa. Population heterogeneities for ecological and behavioral attributes expand and stabilize malaria transmission over space and time, and populations may change in response to vector control, urbanization and other factors. There is a need for approaches to comprehensively describe the structure and characteristics of a sympatric local mosquito population, because incomplete knowledge of vector population composition may hinder control efforts. To this end, we used a genome-wide custom SNP typing array to analyze a population collection from a single geographic region in West Africa. The combination of sample depth (n = 456) and marker density (n = 1536) unambiguously resolved population subgroups, which were also compared for their relative susceptibility to natural genotypes of Plasmodium falciparum malaria. The population subgroups display fluctuating patterns of differentiation or sharing across the genome. Analysis of linkage disequilibrium identified 19 new candidate genes for association with underlying population divergence between sister taxa, A. coluzzii (M-form) and A. gambiae (S-form).
Acta Tropica, 2004
There has been an increase in malaria cases in southern African countries in recent years due to the presence of populations of Anopheles funestus that are resistant to the pyrethroid class of insecticides. Since A. funestus is one of the major African malaria vectors, knowledge of its genetic structure will benefit control strategies, such as the management of insecticide resistance, by allowing predictions to be made of possible spread of the resistance. This study uses microsatellite DNA markers to analyze samples from five countries in east (Kenya and Uganda), central (Malawi) and southern (South Africa and Mozambique) Africa. There were deviations from Hardy-Weinberg expectations for some loci in all population samples but this was probably due to the presence of null alleles. High levels of genetic diversity were observed (mean alleles per locus = 6.5-10; unbiased H = 0.23-0.89). Low differentiation was observed between Kenya and Uganda (average F ST = 0.002, R ST = 0.0001) and between Mozambique and South Africa (F ST = 0.0004, R ST = 0.02), contrary to high differentiation among the central and southern Africa samples (average F ST = 0.023, R ST = 0.027). High differentiation was measured across the region (mean F ST = 0.04, R ST = 0.08), east versus Malawi (F ST = 0.067, R ST = 0.089) or southern Africa populations (F ST = 0.068, R ST = 0.15). A test of isolation by distance along the east-central-south transect gave evidence (R 2 = 0.50, P < 0.001) that geographic distance limits gene flow in A. funestus.
Population genetic structure of the African malaria mosquito Anopheles funestus in Kenya
The American journal of tropical medicine and hygiene, 2003
Anopheles funestus Giles is a major malaria vector in Africa, but little is known about the genetic structure of natural populations. In this study, microsatellite markers were used to investigate the genetic structure of A. funestus populations from Kenya. Two populations from western Kenya 80 km apart and two from coastal Kenya 50 km apart were collected and examined for allelic variation at five trinucleotide microsatellite loci. We found A. funestus Giles was the predominant species (> 98%) in the A. funestus group in these populations. The western Kenya populations exhibited higher genetic diversity than the coastal populations. No significant genetic structure for populations within the coastal or western Kenya regions was detected. However, population genetic differentiation between the two regions was high (F(ST) = 0.208, R(ST) = 0.158), approximately two-fold higher than A. gambiae populations from the same area. The results suggest that the minimum area associated with ...