Spread of Phenotypic Plasticity or Genetic Assimilation: The Possible Role of Genetic Constraints

This paper considers possible outcomes of evolution in sexual diploid populations subjected to frequency-independent selection in favour of a phenotype which has appeared as a consequence of a change in environmental conditions. Depending on the details of genetic determination for the different development strategies ("plastic" or "canalized"), this situation results at least in either (i) the invasion of the population by "plastic" strategists, whose developmental plasticity was revealed by the environmental change, or (ii) the genetic assimilation of the new phenotype, or (iii) intermediate states in which only a certain proportion of individuals is genetically assimilated at equilibrium. Spread of plasticity during evolution in a series of distinct environments might, therefore, be hindered by genetic constraints.