Chromatin diminution in Copepoda (Crustacea): pattern, biological role and evolutionary aspects

Abstract. This article provides an overview of research on chromatin diminution (CD) in copepods. The phenomenology, mechanisms and biological role of CD are discussed. A model of CD as an alternative means of regulating cell differentiation is presented. While the vast majority of eukaryotes inactivate genes that are no longer needed in development by heterochromatinization, copepods probably use CD for the same purpose. It is assumed that the copepods have exploited CD as a tool for adaptation to changing environmental conditions and as a mechanism for regulating the rate of evolutionary processes.