Schematic representation of evolutionary breakpoint regions, evolutionary breakpoints, and evolutionary chromosomal bands. An evolutionary breakpoint region is defined as the interval between two syntenic blocks 4 megabases (Mb) or less in size. This is done in order to avoid problems of low comparative coverage. Evolutionary breakpoints are defined by sequences coordinates in any of the seven mammalian species compared with human plus the chicken, and serve to delimit the start and end of each breakpoint region. Evolutionary chromosomal bands correspond to any band in the human ideogram that contains at least one evolutionary breakpoint in any of the eight species compared with the human genome.