How is hereditary variability manifested?
Mutations occurring in the body lead tothe formation of certain deviations. Depending on which cells and at what stage they occur, hereditary variability can appear, i.e. such changes that are transmitted by hereditary pathway to subsequent cells. Changes are made to certain signs of the organism, depending on the genotype. They can persist for several generations, and in some cases, there is an accumulation of such deviations.
Hereditary variability can be expressed inconcrete transformations, serious enough to immediately identify them. Albinism of the organism is an example of mutations and hereditary changes, here one can attribute the absence of feathering or horns in domestic animals and other similar signs. In vegetation, this phenomenon also happens - deviation in the size of the petals or plant height, other obvious deviations from the norm. All this is a consequence of mutations and is included in the concept of hereditary changes in the body.
Mechanisms of formation
In any group of individuals that coexist during thea certain period of time, spontaneous mutations are formed. They are combined randomly on the basis of already existing hereditary traits. The more deviations, the more likely the occurrence of new changes, which further away from the norm.
Mutations occur during the formation of cells. At the stage of fusion of gametes, recombination of genes occurs, which is the main cause of variability. The cause may be discrepancy of chromosomes or their accidental combination during meiosis or fertilization. Because of the manifestation at such an early stage, hereditary variability is formed.
However, mutations do not occur spontaneously oraccidentally, they are caused by the influence of certain factors. Mutagen can be radiation exposure, biological or viral impact, chemicals.
If the cell in which the mutations occurred,retains the ability to reproduce itself, it is likely that hereditary variability will be formed. Changes can be genomic, genomic or chromosomal, depending on where they appear.
Mutations in evolution
Hereditary variability in the course of evolution had a noticeable effect on organisms. Its significance is large enough, and for the first time this phenomenon and its mechanisms began to be studied as far back as the 18th century.
Charles Darwin said that every organismsubject to individual variability. Its main characteristics he called randomness, relative rarity and non-directional character. This significantly complicated attempts to predict the process or any predictions.
However, mutations also led to the formation ofreserve of hereditary variability, the formation of various genotypes. Nevertheless, in nature such a function is mainly performed by combinative variability - during sexual reproduction, recombination of chromosomes takes place. As a result, the compatibility of genes and their interaction in the genotype changes, but the genes themselves do not change, therefore, there are no abnormalities.
These processes help to better understand howthere is a modification and hereditary variability. From the point of view of evolution, individual differences matter. When it comes to the manifestation of hereditary changes, not only the presence of anomalous genes, but also their combination with other genes that are part of the genotype, is also taken into account, in addition, the environmental conditions and the direct development of the organism can in one way or another influence.
On the one hand, the precise transfer of gene material from one generation to another is important, but, on the other hand, the preservation of information contained in genes can be extremely harmful to the body.