Evolution and stress-genotypic and phenotypic components

TLDR

Stress that reduces growth or performance can drive classical evolutionary changes when genetic variability exists, yet stress may also be temporary or fluctuating, producing complex, behavior‑like response systems. The study proposes that facultative, phenotypically plastic adaptations are more suitable under temporary or fluctuating stress. Evidence shows that plants evolve constitutive, stress‑specific adaptations and develop diverse morphological or physiological phenotypic response systems under fluctuating stress, which are genetically controlled and products of normal evolutionary processes.

Abstract

Since stress can be defined as anything which reduces growth or performance, it follows that, if appropriate genetic variability is present, classical evolutionary changes in populations are to be expected in any situation where a consistent stress is occurring. There is now considerable evidence for such evolution, producing constitutive adaptations in plants in response to stress, which are specific to the stress concerned. Stress may however operate in a temporary or fluctuating manner. In these situations, facultative adaptations, able to be produced within a single genotype through phenotypic plasticity, will be more appropriate. Very different specific phenotypic response systems, both morphological or physiological, can be found in plants in relation to different fluctuating stresses, operating over a wide range of time scales. These response systems are under normal genetic control and appear to be products of normal evolutionary processes. They can however have quite complex features, analogous to the behavioural response systems in animals.