Figure 4

Model for the evolution of the SR genes in flies. Schematic diagram showing conservation of microsynteny of sugar Grs in Drosophila melanogaster (blue), Anopheles gambiae (red), Aedes aegypti (green) and Culex pipiens (yellow). Most of the genes share both phylogenetic relatedness and similar placement in chromosomes (Ae. gambiae and D. melanogaster) and supercontigs (Ae. aegypti and C. pipiens) across the four species, even after duplication events (shown with line 1 and lines 2, as in Fig. 3). Although it appears that some genes have moved within their respective genomes in D. melanogaster and An. gambiae (shown with grey arrows), their phylogenetic relationships (Fig. 3) reveal where they most likely had previously resided on the chromosomes. Likewise, it appears that there has been some level of gene shuffling in Ae. aegypti and C. pipiens (shown with pink arrows) with respect to the arrangements seen in D. melanogaster and An. gambiae. Although the genes have not yet been mapped to Aedes and Culex chromosomes, the ordered supercontigs of the genome sequences are likely accurate representations of microsynteny in each species.