Dauers, sexual plasticity and variant mouth forms: lessons on phenotypic plasticity from phylum nematoda

Abstract

Organisms develop and evolve in diverse environment. This environment modulates the translation of genotype into phenotype. Phenotypic plasticity or polyphenism is defined as a phenomenon where an organism adopts different phenotypes depending on the environment. Alternatively, a phenotype may be insensitive to a given set of environmental conditions - a phenomenon called as ‘environmental robustness’. Nematodes are one of the best models in Kingdom Animalia to study the environment-specific responses of organisms because of specific characteristics, viz., species richness, omnipresence, numerical abundance etc. Formation of dauer larvae under unfavorable conditions, alternate life cycles of certain parasitic nematodes, different mouth morphology and environment induced sexual flexibility are classic examples of phenotypic plasticity in nematodes. However, the knowledge of molecular mechanisms underlying phenotypic plasticity is still scant, and a lot more research is required to understand it better and propose a unified theory for phenotypic plasticity in organisms.