Gene expression and the evolution of insect polyphenisms

Polyphenic differences between individuals arise not through differences at the genome level but as a result of specific cues received during developm ent. Polyphenisms often involve entire suites of characters, as shown drama tically by the polyphenic castes found in many social insect colonies. An u nderstanding of the genetic architecture behind polyphenisms provides a nov el means of studying the interplay between genomes, gene expression and phe notypes. Here we discuss polyphenisms and molecular genetic tools now avail able to unravel their developmental bases in insects. We focus on several r ecent studies that have tracked gene-expression patterns during social inse ct caste determination. Published 2001 John Wiley & Sons, Inc.(dagger).