Circular genetic map. Genetic map of contigs (far left to far right of inner circle) and clones (outer ring) from a DNA fingerprinting sequence (blue, lower part of inner ring) of the Chlamydia bacterium. A contig (from contiguous) is a set of overlapping DNA segments derived from a single genetic source. A map of contigs allows the study of large segments of a genome by examining a series of overlapping clones. By arranging the map in a circle, it is possible to link the clone's position in the map with the position in the sequence (black lines within circle). This map was created using Circos, software which visualises complex genetic comparisons between the genomes of different species or within the same species.