An increasing number of “non-model” organisms are becoming accessible to genetic analysis in the field, as evolutionary biologists develop dense molecular genetic maps. Peichel et al.'s recent study1 provides a microsatellite-based map for threespine stickleback fish (Gasterosteus aculeatus), and the first evidence for QTL affecting feeding morphology and defensive armor. This species has undergone rapid and parallel morphological and behavioral evolution, and there is now hope that some of the genes responsible for the divergence may soon be identified. BioEssays 24:487–489, 2002. © 2002 Wiley Periodicals, Inc.