Circular genome map. Map showing the genetic content within a chromosome (outer ring). The chromosome is based on a standard idiogram and arranged in a circle. Within the circle are graphs and histograms displaying the guanine and cytosine (gc-content) content of the genes within the chromosome. The species gc-content is used to classify organisms. This map was created using Circos, software which visualises complex genetic comparisons between different species or within the same species.