Evidence for subdivision within the M molecular form of Anopheles gambiae

• Published in: Molecular ecology Vol. 16; no. 3; pp. 639 - 649
• Main Authors: SLOTMAN, M.A, TRIPET, F, CORNEL, A.J, MENESES, C.R, LEE, Y, REIMER, L.J, THIEMANN, T.C, FONDJO, E, FOFANA, A, TRAORÉ, S.F, LANZARO, G.C
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.02.2007; Blackwell Publishing Ltd
• Subjects: Alleles; Animal populations; Animals; Anopheles - classification; Anopheles - genetics; Anopheles gambiae; Cameroon; chromosomal form; Chromosome Inversion; Chromosomes; Chromosomes - genetics; Ecosystem; Female; Genetic diversity; Genetic Speciation; Habitats; incipient speciation; inversions; isolation; Linkage Disequilibrium; Mali; Molecular biology; molecular form; Mosquitoes; Phylogeny; Africa
• ISSN: 0962-1083; 1365-294X
• DOI: 10.1111/j.1365-294X.2006.03172.x

The principal vector of malaria in sub-Saharan Africa, Anopheles gambiae is subdivided into two molecular forms M and S. Additionally, several chromosomal forms, characterized by the presence of various inversion polymorphisms, have been described. The molecular forms M and S each contain several chromosomal forms, including the Savanna, Mopti and Forest forms. The M and S molecular forms are now considered to be the reproductive units within A. gambiae and it has recently been argued that a low recombination rate in the centromeric region of the X chromosome has facilitated isolation between these forms. The status of the chromosomal forms remains unclear however. Therefore, we studied genetic differentiation between Savanna S, Forest S, Forest M and Mopti M populations using microsatellites. Genetic differentiation between Savanna S and Forest S populations is very low (FST = 0.0053 ± 0.0049), even across large distances. In comparison, the Mopti M and Forest M populations show a relatively high degree of genetic differentiation (FST = 0.0406 ± 0.0054) indicating that the M molecular form may not be a single entity, but could be subdivided into at least two distinct chromosomal forms. Previously it was proposed that inversions have played a role in the origin of species within the A. gambiae complex. We argue that a possible subdivision within the M molecular form could be understood through this process, with the acquisition of inversions leading to the expansion of the M molecular form into new habitat, dividing it into two distinct chromosomal forms.