Mosaic genome architecture of the Anopheles gambiae species complex.
BACKGROUND
Attempts over the last three decades to reconstruct the phylogenetic history of the Anopheles gambiae species complex have been important for developing better strategies to control malaria transmission.


METHODS
We used fingerprint genotyping data from 414 field-collected female mosquitoes at 42 microsatellite loci to infer the evolutionary relationships of four species in the A. gambiae complex, the two major malaria vectors A. gambiae sensu stricto (A. gambiae s.s.) and A. arabiensis, as well as two minor vectors, A. merus and A. melas.


RESULTS
We identify six taxonomic units, including a clear separation of West and East Africa A. gambiae s.s. S molecular forms. We show that the phylogenetic relationships vary widely between different genomic regions, thus demonstrating the mosaic nature of the genome of these species. The two major malaria vectors are closely related and closer to A. merus than to A. melas at the genome-wide level, which is also true if only autosomes are considered. However, within the Xag inversion region of the X chromosome, the M and two S molecular forms are most similar to A. merus. Near the X centromere, outside the Xag region, the two S forms are highly dissimilar to the other taxa. Furthermore, our data suggest that the centromeric region of chromosome 3 is a strong discriminator between the major and minor malaria vectors.


CONCLUSIONS
Although further studies are needed to elucidate the basis of the phylogenetic variation among the different regions of the genome, the preponderance of sympatric admixtures among taxa strongly favor introgression of different genomic regions between species, rather than lineage sorting of ancestral polymorphism, as a possible mechanism.
European Molecular Biology Laboratory, Heidelberg, Germany.
Rui
R
Wang-Sattler
Stephanie
S
Blandin
Ye
Y
Ning
Claudia
C
Blass
Guimogo
G
Dolo
Yeya T
YT
Touré
Alessandra
A
delle Torre
Gregory C
GC
Lanzaro
Lars M
LM
Steinmetz
Fotis C
FC
Kafatos
Liangbiao
L
Zheng
D000818:Animals; D000852:Anopheles / Q000145:classification / Q000235:genetics*; D005075:Biological Evolution; D022202:Chromosomes, Artificial, Bacterial; D005260:Female; D005819:Genetic Markers; D014644:Genetic Variation; D016678:Genome; D018895:Microsatellite Repeats / Q000235:genetics; D009030:Mosaicism
D005819:Genetic Markers