Brief communication. The Rift Valley complex as a barrier to gene flow for Anopheles gambiae in Kenya: the mtDNA perspective

Abstract

Descriptions of A. gambiae population structure based on microsatellite loci and mitochondrial DNA (mtDNA) were incongruent. High differentiation of populations was measured across the Rift Valley by microsatellites, but no differentiation was detected based on mtDNA. To resolve this conflict, we compared the old data to new mtDNA data using the same specimen previously genotyped in microsatellite loci. Analysis of a larger number of mtDNA sequences resulted in high and significant differentiation between populations across the Rift Valley. We developed a method to assess whether differentiation across the Rift Valley was generated by pure drift rather than mutation-drift, based on DNA sequence data. Applying this method to the mtDNA data suggested that pure drift was the primary force generating differentiation between the populations across the Rift, while mutation-drift generated differentiation across the continent. Given adequate sample size, mtDNA provided congruent results with microsatellite loci.

Population differentiation of Phlebotomus perniciosus in Spain following postglacial dispersal

“…By analogy with An. gambiae (Lehmann et al, 2000), the lack of unique alleles and the higher F ST than Rho ST values among northeastern populations of P. perniciosus both suggest that pure drift was the main differentiating process for the northeastern region of Spain. This is consistent with the hypothesis of historical migration from a southern Ice Age refuge, with the northeastern population arising as a northern peripheral isolate in which founder effects and bottleneck events led to the loss of rare alleles and significant changes in allele frequencies, as argued for temperate European insects (Hewitt, 1996(Hewitt, , 1999.…”

“…Such studies of insect transmitters of disease are potentially important for planning intervention strategies, as they can help predict the dispersal not only of vectorial traits associated with specific populations but also of genetically modified organisms and the genes they carry. The interest of this approach has been demonstrated for the Anopheles gambiae complex, which contains most of the major vectors of human malaria in sub-Saharan Africa (Lehmann et al, 1996(Lehmann et al, , 2000Donnelly and Townson, 2000).…”

The Effects of Climatic Factors on the Distribution and Abundance of Malaria Vectors in Kenya

“…arabiensis in Kenya have implications on the population genetic structure of anopheline mosquitoes. Lehmann et al (1999Lehmann et al ( , 2000 demonstrated that An. gambiae populations from western Kenya were highly differentiated genetically from Kenyan coastal populations, suggesting that the Great Rift Valley plays an important role in limiting An.…”

Population genetic structure of the malaria vector Anopheles minimus A in Vietnam

“…Yet, significant isolation between coastal and savannah An. gambiae populations from Kenya, 700 km away, has been recorded (McLain et al, 1989;Kamau et al, 1999;Lehmann et al, 1999Lehmann et al, , 2000. These populations are separated by the eastern arm of the Rift valley complex.…”