DIFFERENT PATHWAYS IN ARTHROPOD POSTEMBRYONIC DEVELOPMENT

To investigate the consequences of canalization and plasticity in arth ropod developmental pathways, we developed a model that predicts eight possible combinations among three larval developmental parameters. Fr om the descriptions of insect and spider postembryonic development, it is apparent that not all aspects of juvenile development are plastic and that species differ in which traits are plastic. Most strikingly, only four of the possible eight combinations of canalized and plastic parameters have been found in nature. Using this model, we show that t he identity of the canalized developmental parameters and the degree o f genetic variation in the value at which a given parameter is fixed h ave important implications for the ecology and evolution of complex li fe cycles.