Evolution and development of pigment cells: at the crossroads of the discipline.

The following is a summary of the current state of comparative biology with respect to pigmentation. Recent results from molecular analyses of genes involved in pigmentation in lower vertebrates are compared with similar data from mouse and man. Particular emphasis has been placed on evolutionary and developmental aspects of pigmentation. Recent advances in molecular biology of lower vertebrate pigmentation allow for the comparison of orthologous molecules across a wider range of species than ever before; some of these results are summarized and used to highlight the current state of pigmentation from a comparative perspective. A more cellular, organismal approach is also explored to highlight some important lessons from comparative biology. Lastly, large-scale evolutionary questions are put into a framework that highlights both the differences and similarities between mammals/birds and other vertebrates. It is the opinion of the authors that important, long-standing questions in these areas can now be addressed in ways that have not been possible before. Thus, the discipline is at an exciting crossroads where developmental and evolutionary data can be used to create a unified view of pigment cells and pigments across many species.