Developmental Plasticity and Robustness

Organisms are subject to various sources of variations. A major question in biology is to dissect the mechanisms that allow them to cope with these sources of variation or to exploit them. Developmental robustness describes the ability of organisms to maintain a constant phenotype despite genetic variation, environmental variation and developmental noise. On the other hand, phenotypic plasticity describes the ability of a given genotype to produce distinct phenotypes in different environments. Phenotypic plasticity is widely observed and is often an adaptation to predictable fluctuating environmental conditions. Developmental robustness and phenotypic plasticity have been the subject of many descriptive studies. It is only rather recently that the molecular mechanisms involved in these processes have been tackled. For example, the chaperone HSP90 was shown to play a major role in developmental robustness, but developmental robustness was also shown to be an emerging property of gene regulatory networks. Hormonal control and epigenetic mechanisms were shown to mediate phenotypic plasticity in many cases. Several studies have lead to the identification of developmental genes modulated by environmental conditions.

Comparison of the genes involved in developmental plasticity and robustness with those involved in morphological divergence between species allows us to analyse how the different sources of variation might be involved in evolution. Indeed, phenotypic plasticity is thought to facilitate evolution and the “flexible stem hypothesis” proposes that in some cases an ancestral plastic species can be at the origin of sister lineages with divergent phenotypes obtained by genetic assimilation of the alternative morphs present in the ancestral species. Furthermore, robustness allows the accumulation of cryptic genetic variation that can be released in particular conditions such as stress, thus contributing to evolution.

Hence, the scope of the Research Topic we propose is to present the current state of research in the genetics and epigenetics of developmental plasticity and robustness using a variety of organisms and approaches. We plan to propose to the contributing authors to write either Original Research or Reviews on the model organism they study. The combination of all these articles in the same Research Topic should be extremely fruitful and lead to the emergence of shared principles.