PATTERN-FORMATION AND EYESPOT DETERMINATION IN BUTTERFLY WINGS

Butterfly wings display pattern elements of many types and colors. To identify the molecular processes underlying the generation of these pa tterns, several butterfly cognates of Drosophila appendage patterning genes have been cloned and their expression patterns have been analyze d. Butterfly wing patterns are organized by two spatial coordinate sys tems. One system specifies positional information with respect to the entire wing field and is conserved between fruit flies and butterflies . A second system, superimposed on the general system and involving se veral of the same genes, operates within each wing subdivision to elab orate discrete pattern elements. Eyespots, which form from discrete de velopmental organizers, are marked by Distal-less gene expression. The se circular pattern elements appear to be generated by a process simil ar to, and perhaps evolved from, proximodistal pattern formation in in sect appendages.