Modification variability is a rather important property of organisms to adapt to the external environment. This is a complex of reactions that are a physiological adaptation of an organism or a whole population to a change in environmental conditions. For example, under the sun, the skin more or less darkens in every person.
Modification variability and its properties
This property of organisms has some characteristic features:
- Modification variability affects exclusively the phenotype (external characters), but does not affect the genotype (individual set of genetic information).
- It is of a group nature - if some environmental conditions affect a group of organisms, then all of its representatives show the appearance of the same signs.
- Reversibility - changes appear under the constant influence of certain factors. If you transfer the body to other conditions or eliminate the influence of the factor, then phenotypic changes disappear.
- Changes that occur under the influence of external factors are not inherited.
It is worth noting that modification variability is of great importance for the process of natural selection. The fact is that in nature those organisms survive that are most adapted to conditions, especially with a sharp change in external factors. Combinatorial and mutational variability far from completely provides the body with the ability to adapt.
Modification Variability: Examples
In nature, you can find countless examples of such changes in the body. Below are the most common.
- When climbing mountains, where environmental conditions change, an increase in the number of red blood cells is observed in the blood of a person or an animal, which ensures normal oxygen nutrition.
- When exposed to ultraviolet rays in the skin tissues, increased release of pigments begins.
- As a result of constant intensive training, muscle mass is significantly increased. After the termination of classes, the body gradually loses elasticity, muscles decrease in size.
- If the white Himalayan hare is moved to moderate climatic conditions and the body area is shaved, the new coat will be gray.
- If the trees already have fully blossomed leaves, and at night they will be affected by minus temperature, then in the morning you will notice a characteristic reddish tint.
In order to understand the nature of modification devices, it is necessary to consider other forms of variability.
Combinatorial variability
Such variability results from gene recombination during gamete fusion. Now consider an example: if the father of the child has green eyes and dark hair, and the mother has blond hair and blue eyes. A baby can be born with green eyes and blond hair, or dark hair and blue eyes. It is such phenotypic changes in the offspring that are provided by combinatorial variability.
Mutational variability
Changes occur when exposure to mutagens of a chemical, physical or biological nature. Mutation mutation as opposed to modification:
- arises spontaneously, and it is almost impossible to predict it;
- causes changes in genetic material;
- mutational changes are persistent and inherited;
- mutations can be either benign or cause pathology up to death;
- they do not depend on environmental conditions;
- arise in individual individuals;
As you can see, variability is a very complex process that affects both the genotype and phenotypic characteristics. It is thanks to modifications, combinations and mutations that organisms gradually changed, improving and adapting to changes.