Evidence for subdivision within the M molecular form of Anopheles gambiae.
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 (F(ST) = 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 (F(ST) = 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.
Slotman
M A
MA
Department of Entomology & Center for Vectorborne Diseases, University of California Davis, Davis, CA 95616, USA. michel.slotman@yale.edu
Tripet
F
F
Cornel
A J
AJ
Meneses
C R
CR
Lee
Y
Y
Reimer
L J
LJ
Thiemann
T C
TC
Fondjo
E
E
Fofana
A
A
Traoré
S F
SF
Lanzaro
G C
GC
D000483:Alleles; D000818:Animals; D000852:Anopheles / Q000145:classification* / Q000235:genetics*; D002163:Cameroon; D007446:Chromosome Inversion; D002875:Chromosomes / Q000235:genetics; D017753:Ecosystem; D005260:Female; D049810:Genetic Speciation; D015810:Linkage Disequilibrium; D008302:Mali; D010802:Phylogeny