Developmental genetics of adaptation in fishes: The case of novelty

During the past decade of study in evolutionary developmental biology, we have seen the focus shift away from the stunning conservation of form and function between distantly related taxa toward the causal explanation of differences between closely related species. A number of fish models have emerged at the forefront of this effort to dissect the developmental genetic and molecular basis of evolutionary novelty and adaptation. We review the highlights of this research, concentrating our attention on skeletal morphology (cranial and postcranial), pigmentation patterning, and sex determination. Thus far, the genes involved in adaptation among fishes belong to well-characterized molecular pathways. We synthesize the current state of knowledge to evaluate theories about the interplay between development and evolution. General rules of evolutionary change have not materialized; however, the field is wide open, and fishes will likely continue to contribute insights to this central biological question.