Chapter 9 - Transgenerational Developmental Plasticity—An Epitome of Evolutionary Change

Abstract

Metazoans sometimes respond to specific environmental stimuli by adaptive phenotypic changes in their offspring. Such cases of transgenerational developmental plasticity (TDP) are causally not different from evolutionary changes. Induction of new phenotypic characters in the offspring involves no mutations in genes, as indicated by the fact that the changes affect simultaneously whole populations. What essentially takes place during the transgenerational developmental plasticity is that specific environmental stimuli are received by sensory neurons which convert them into electrical spike trains that are transmitted for processing in specific neural circuits in the CNS. The processing generates epigenetic information in the form of a chemical output (neurotransmitter, neuromodulator, etc.) that is released on specific secretory neurons, which in turn secrete a neurohormone (neuropeptide) that starts a signal cascade resulting in deposition in gamete(s) of a parental cytoplasmic factor (or an epigenetic mark) that determines the development of the new phenotypic character in the offspring.