| Summary: | <p>Abstract</p> <p>Background</p> <p>Mosquito vitellogenin (<it>Vtg</it>) genes belong to a small multiple gene family that encodes the major yolk protein precursors required for egg production. Multiple <it>Vtg </it>genes have been cloned and characterized from several mosquito species, but their origin and molecular evolution are poorly understood.</p> <p>Results</p> <p>Here we used <it>in silico </it>and molecular cloning techniques to identify and characterize the evolution of the <it>Vtg </it>gene family from the genera <it>Culex</it>, <it>Aedes/Ochlerotatus</it>, and <it>Anopheles</it>. We identified the probable ancestral <it>Vtg </it>gene among different mosquito species by its conserved association with a novel gene approximately one kilobase upstream of the start codon. Phylogenetic analysis indicated that the <it>Vtg </it>gene family arose by duplication events, but that the pattern of duplication was different in each mosquito genera. Signatures of purifying selection were detected in <it>Culex</it>, <it>Aedes </it>and <it>Anopheles</it>. Gene conversion is a major driver of concerted evolution in <it>Culex</it>, while unequal crossover is likely the major driver of concerted evolution in <it>Anopheles</it>. In <it>Aedes</it>, smaller fragments have undergone gene conversion events.</p> <p>Conclusions</p> <p>The study shows concerted evolution and purifying selection shaped the evolution of mosquito <it>Vtg </it>genes following gene duplication. Additionally, similar evolutionary patterns were observed in the <it>Vtg </it>genes from other invertebrate and vertebrate organisms, suggesting that duplication, concerted evolution and purifying selection may be the major evolutionary forces driving <it>Vtg </it>gene evolution across highly divergent taxa.</p>
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