GENESIS VERSUS EPIGENESIS - THE ODD JOBS OF THE POLYCOMB GROUP OF GENES

Cells need the products of the Polycomb Group of genes (PcG) to keep, through development, the memory of their genetic determination. The pl eiotropic mutant phenotypes of PcG genes strikingly resemble morpholog ical traits, considered as taxonomic characters with phylogenetic mean ing, used in Dipteran classification. I argue that spatial modulation of the multimeric complexes formed by PcG products has played a role o r escorted the genesis of species.