The availability of complete genome sequences and genetic linkage maps for a growing number of mammalian species is opening up exciting new opportunities for studies of evolutionary change in natural populations. For example, multilocus mapping approaches hold the promise of identifying the specific genetic changes that underlie ecological adaptation and reproductive isolation. The fact that many of the genomic resources that have been developed for Mus and Rattus are transferable to other muroid rodents means that roughly 25% of all mammalian species can now be considered “genome-enabled” study organisms to varying degrees. The transferability of genomic resources between model organisms and their more ecologically interesting kin should usher in a renaissance period of research on adaptation and speciation in mammals.