Ontogenetic variability. Causes and significance

How to survive some of the weaker species in heavynatural conditions? For their survival, an adaptation mechanism is built into their genes, that is, changes in their properties under the action of natural forces such as air temperature, wind, and sun.

The genetic program determines the formationbutterflies from a pupa and development of an adult fish from a small egg. During this long-term development, all endogenous and exogenous factors will be reflected in the phenotype of the individual.

This is ontogenetic variation. Her examples in nature are endless. It is interesting to understand how the adaptation is arranged.

Variability in biology. Types of variability

В официальной науке есть такое понятие, как variability. It determines how the adult organism will develop and what signs it will acquire in the process of its development. Variability in general is the ability of an organic to acquire new properties.

There are genetic and non-geneticvariability. Non-genetic does not affect the gene structure. Changes occur only within the normal range of the reaction. That is, the phenotype changes as much as the genotype allows. Non-genetic variation is modifying and ontogenetic. The latter is also called epigenetic variability.

Ontogenetic variation

The individual organism is formed in stages.During each stage, it is affected by various environmental factors. After all, any living creature cannot develop in isolation. And as a result of the impact of certain factors, the body acquires new signs.

Ontogenetic variation is found onthe intersection of genetic variation and non-genetic. Differently, it is also called epigenetic variability. Why is that? This type of variability differs from others in that new features appear as a result of the genetic programs laid down, and at the same time due to environmental features. Without such programs, nature would have doomed many living creatures to extinction.

The concept of ontogeny

Что такое онтогенез?This concept is one of the basic in the course of biology. To better understand what is ontogenetic variation, you need to know about the process of ontogenesis. In fact, scientists have identified a type of variability based on this particular process.

Ontogenesis is a process of development from the momentconception before birth. It is easy to follow this process on the example of butterfly development. Initially, a caterpillar is born (Fig. 1), a pupa is formed from it (Fig. 2, 3), which is also the cycle of life. And from the pupa an adult individual flies out - a butterfly. Ontogenesis is also characteristic of plants.

Anything that happens to a zygote (fertilized egg) before the formation of an animal or human is complete can be studied and analyzed.

Examples in nature

The causes of developmental variability, based on the foregoing, are environmental conditions and genotype features. A genotype is like a formula that regulates all changes.

How does genotype regulate variability?The genotype of an individual regulates the work of certain genes, which must "engage" in a certain period of development. It is not the trait itself that is inherited by a specific organism, but the type of reaction to a certain effect of the environment. This is the law of nature, which holds the key to understanding such a process as developmental variability. Examples of such variability will be found in different countries and on different continents. Such variability is characteristic of animals, and insects, and the plant kingdom.

Let us trace the change in color and shape of the skin of the Andean toad living in Ecuador. Its transformation in the period of ontogenesis is the classic "formula" of ontogenetic variability in nature.

The little toad does not have bumps along the body,adult individual, as we see, has growths on its sides. The toad's skin color changes to coppery brown; and the color of the iris of bright red becomes copper-orange.

Value of variability

The value of developmental variability for livingnature - first of all, the adaptation of each individual. The better it is, the greater the viability of the species in the environment. Another value of variability is a variety of phenotypes. Each individual, due to variability, has its own individual characteristics.

Thanks to improved adaptation, the entire species evolves. Although, of course, these changes are very slow.