Genetic differentiation of Anopheles gambiae populations from East and West Africa: comparison of microsatellite and allozyme loci

Abstract

Genetic variation of Anopheles gambiae was analysed to assess interpopulation divergence over a 6000 km distance using short tandem repeat (microsatellite) loci and allozyme loci. Differentiation of populations from Kenya and Senegal measured by allele length variation at five microsatellite loci was compared with estimates calculated from published data on six allozyme loci (Miles, 1978). The average Wright's FST of microsatellite loci (0.016) was lower than that of allozymes (0.036). Slatkin's RST values for microsatellite loci were generally higher than their FST values, but the average RST value was virtually identical (0.036) to the average allozyme FST.These low estimates of differentiation correspond to an effective migration index (Nm) larger than 3, suggesting that gene flow across the continent is only weakly restricted. Polymorphism of microsatellite loci was significantly higher than that of allozymes, probably because the former experience considerably higher mutation rates. That microsatellite loci did not measure greater interpopulation divergence than allozyme loci suggested constraints on microsatellite evolution. Alternatively, extensive mosquito dispersal, aided by human transportation during the last century, better explains the low differentiation and the similarity of estimates derived from both types of genetic markers.

Semipermeable species boundaries betweenAnopheles gambiaeandAnopheles arabiensis: Evidence from multilocus DNA sequence variation

“…With respect to the paradox of broadly distributed shared haplotypes, it is noteworthy that for each of the four loci, the amount of variation distributed among populations within species was either insignificant (white, tox, 2R arrangements, and xdh) or very minor (G6pd). This finding is consistent with previous mtDNA and microsatellite studies that have suggested shallow population structure (14,29,30). Without well defined geographic population structure, localized introgression events cannot readily be perceived as such (16).…”

Gene Flow Across Species Boundaries in Sympatric, Sexually Deceptive Ophrys (Orchidaceae) Species

“…Direct comparisons of both markers in plants and animals have reported higher microsatellite variation than allozyme variation, but found inconsistent results with respect to genetic differentiation among populations. In wild rice, microsatellites detected higher genetic differentiation among populations (Gao et al 2002), whereas the opposite was found for Anopheles mosquitoes (Lehmann et al 1996).…”

An island within an island: genetic differentiation of Anopheles gambiae in São Tomé, West Africa, and its relevance to malaria vector control

“…In a population at MDE, both estimates should be equal (ie, H e ¼ H eq ). If (Lehmann et al, 1996;Zheng et al, 1996). All loci are located outside polymorphic chromosomal inversions 2La, 2Rb and 2Rd known to occur at very low frequencies in the Forest cytoform of A. gambiae s.s. (Coluzzi et al, 1985).…”

“…Estimates are within the range of those found in A. gambiae mainland populations. Long-term N e values (IAM-SMM) around 6500-21 000 (Senegambia), 7500-23 000 (Western Kenya), 8500-24 000 (Gabon) and 11 500-49 000 (Cameroon) are derived by reanalysing microsatellite data in previous publications (Lehmann et al, 1996(Lehmann et al, , 1998Pinto et al, 2002;Wondji et al, 2002). In addition, present estimates of long-term N e may also be underestimated.…”