How many sequenced genomes are enough? The minimum number for comparative genomics, researchers say, depends on what you want to learn. The optimum number is a still a mystery.
For identifying cis-regulatory regions such as enhancers and promoters, the genomes of three species that are roughly equidistant evolutionarily is the bare minimum, and more is better, according to Lincoln Stein. Stein, who is at Cold Spring Harbor Laboratory, is first author of a paper on the