Neighborhood conservation of the top 20 candidate orphan genes. This figure shows annotation conservation of the neighbors of orphan genes in four sequenced Streptomyces genomes. The conserved orphan gene is shown in the centre, and the two neighbors on each side are shown in the form of arrows. Each arrow has four sections, corresponding to the four Streptomyces species: S. coelicolor, S. avermitilis, S. griseus and S. scabies. They are colored in blue where the annotation matches that of S. coelicolor. The annotation of the S. coelicolor homolog is listed above each gene if it is conserved in at least one of the other species; if at least two of the other species share another annotation, this is listed in brackets.