Phenotypic variability and its properties

Phenotypic variability is a very important process that ensures the body's ability to survive. It is thanks to it that it is able to adapt to the conditions of the external environment.

For the first time, the modification variability of organisms was noted in the studies of Charles Darwin. The scientist believed that this is how natural selection takes place in the wild.

Phenotypic variability and its main characteristics

It's no secret that in the process of evolution, living organisms constantly changed, adapting to survival in an environment. The emergence of new species was provided by several factors - a change in the structure of the hereditary material (genotypic variability), as well as the appearance of new properties that made the organism viable with changing environmental conditions.

Phenotypic variability has a number of characteristics:

• First, with this form, only a phenotype is affected - a complex of external characteristics and properties of a living organism. The genetic material does not change. For example, two populations of animals that live under different conditions have some external differences, despite the identical genotype.
• On the other hand, phenotypic variability is of a group nature. Changes in structure and properties occur in all organisms of a given population. For comparison, it should be said that the changes in the genotype are single and spontaneous.
• The modification variability is reversible. If we remove those specific factors that caused the reaction from the body, then in time the distinctive features will disappear.
• Phenotypic changes are not inherited, in contrast to genetic modifications.

Phenotypic variability and reaction rate

As already mentioned, phenotype changes are not the result of any genetic modifications. First of all, this is the reaction of the genotype to the influence of environmental factors. In this case, not the very set of genes, but the intensity of their manifestation, changes.

Of course, such changes have their own limits, which are called the norm of the reaction. The reaction norm is the spectrum of all possible changes, from which only those variants are selected which will be suitable for living under certain conditions. This indicator depends solely on the genotype and has its own upper and lower boundaries.

Phenotypic variability and its classification

Of course, the typology of variability is very relative, since all the processes and stages of the development of the organism have not yet been fully studied. Nevertheless, modifications are usually divided into groups, depending on some characteristics.

If you take into account the changed signs of the body, they can be divided into:

• Morphological (changes the appearance of the body, for example, the density and color of the coat).
• Physiological (there are changes in the metabolism and physiological properties of the body, for example, a person who has risen in the mountains, sharply increases the number of red blood cells).

By duration, the following modifications are distinguished:

• Inherited - the changes are present only in that individual or population that has been directly influenced by the external environment.
• Long modifications - they are talked about when the acquired adaptation is transferred to the offspring and remains for another 1-3 generations.

There are also some forms of phenotypic variability that do not always have the same meaning:

• Modifications are changes that bring the body benefits, provide adaptation and normal livelihoods in an environment.
• Morphoses are those phenotype changes that occur under the influence of aggressive, extreme environmental factors. Here the variability goes far beyond the norm of the reaction and can even lead to the death of the organism.