PHENOTYPIC PLASTICITY AND GENETIC ASSIMILATION IN DEVELOPMENT AND EVOLUTION | BIONATURE

In response to external conditions, phenotypic plasticity refers to a genotype's ability to produce multiple alternative forms of morphology, physiological state, and/or behaviour. Non-genetic factors caused by the environment can vary the range of phenotypes expressed, changing the direction of selection and influencing transmitted gene frequencies. The fact that selection operates on observed phenotypes is crucial to understanding how plasticity might influence evolution.

The process of genetic assimilation is one in which a phenotypic character that is initially produced only in response to some environmental influence is taken over by the genotype through a process of selection, allowing it to be formed even in the absence of the environmental influence that was previously required.

Genotypes are one-dimensional ordered arrays (strings) of genes, each of which can be a 'IO,' a 'O,' or a 'x.' The expressions of 01 and O are both constant, however the expression of x is variable and can resemble either the "01" or "O" level. A procedure of random coin tossing is used to achieve the phenotypic flexibility that this implies. Each (genotype is given a fitness value by comparing its phenotype to a pre-determined target phenotype. Our model differs significantly from Hinton's in terms of the expression of fitnesses. The number of individuals attaining reproductive maturity is calculated using fitnesses and the constraint of a given propulation of genotypes. Random mating and a single recombinational event between parents are used in reproduction; one of the two progeny produced becomes an embryonic genotype for the following generation. Phenotypic plasticity, as Hinton and Nowlan (1987) pointed out, changes the geometry of the search space in which evolution occurs and, as we show, accelerates evolution.

We also show that in more realistic models, there is an optimal level of flexibility.

Please see the link :- https://globalpresshub.com/index.php/BN/article/view/602