Every genome sequence needs a good map

High-resolution physical maps of vertebrate species’ chromosomes empower comparative genomics discovery and are indispensable for sequence assembly precision. Beginning in 2003, the NIH–NHGRI launched an initiative that designated 24 species of mammals for low-coverage whole-genome sequencing in order to provide evolutionary context to human genome annotation (Green 2007) (http://www.genome.gov/25521745). Four principal goals were anticipated for the bold sequencing initiative: (1) to discover evolutionarily conserved sequence motifs, particularly outside of protein-coding genes, which are responsible for regulatory and other critical genomic functions; (2) to provide a framework for reconstruction of genome organization, content, and dynamics that have occurred during the mammalian radiations; (3) to empower new models of human disease and heritable phenotypes; and (4) to provide a starting point for assessment of the expansion, contraction, and adaptation of gene families in different evolutionary lineages.