Comparative maps: adding pieces to the mammalian jigsaw puzzle.

Comparative maps display the chromosomal location of homologous genes in different species and highlight genetic segments that are conserved in evolution. These maps are used to study chromosomal changes that occurred during the divergence of mammalian lineages, to identify candidates for hereditary disease genes, and to facilitate mapping in other species. Recently, physical mapping in regions of known conserved linkage has revealed previously undetected chromosomal changes that may provide clues to understanding chromosomal structure and function and evolutionary processes. The availability of these data in electronically accessible formats is critical to the growth and analysis of comparative maps.