Phenotypic variability is a very important process that ensures the body's ability to survive. It is thanks to her that he is able to adapt to environmental conditions.
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 occurs in the wild.
Phenotypic variability and its main characteristics
It's no secret that in the process of evolution, living organisms are constantly changing, adapting to survival in the environment. The emergence of new species was provided by several factors - a change in the structure of hereditary material (genotypic variability), as well as the emergence of new properties that made the body viable under changing environmental conditions.
Phenotypic variability has a number of features:
- Firstly, with this form, only the phenotype is affected - a set of external characteristics and properties of a living organism. Genetic material is not changed. For example, two animal populations that live in different conditions have some external differences, despite the identical genotype.
- On the other hand, phenotypic variability is of a group nature. Changes in the structure and properties occur in all organisms of a given population. For comparison, it is worth saying that genotype changes are single and spontaneous.
- Modification variability is reversible. If you remove those specific factors that caused a reaction from the body, then over time the hallmarks will disappear.
- Phenotypic changes are not inherited, unlike 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, it is not the set of genes that changes, but the intensity of their manifestation.
Of course, such changes have their own limits, which are called the reaction rate. The reaction rate is the spectrum of all possible changes, from which only those options that are suitable for living in certain conditions are selected. 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 are not yet fully understood. Nevertheless, modifications are usually divided into groups, depending on some characteristics.
If we take into account the changed signs of the body, then they can be divided into:
- Morphological (the appearance of the body, for example, the density and color of the coat, changes).
- Physiological (changes in the metabolism and physiological properties of the body are observed; for example, in a person who has ascended the mountains, the number of red blood cells increases sharply).
By duration, modifications are distinguished:
- Non-inherited - changes are present only in that individual or population that has been directly affected by the external environment.
- Long-term modifications - they are talked about when the acquired adaptation is transmitted to the offspring and persists for another 1-3 generations.
There are also some forms of phenotypic variation that do not always have the same meaning:
- Modifications are changes that bring benefits to the body, ensure adaptation and normal functioning in the environment.
- Morphoses are those phenotype changes that occur under the influence of aggressive, extreme environmental factors. Here, the variability goes far beyond the limits of the reaction norm and can even lead to the death of the organism.