Mutational process as a factor of evolution

The mutational process of evolution is one of thethe most important links in development. In most cases, initially it has an adverse effect on the phenotype of individuals. However, being recessive, altered alleles are present, as a rule, in gene pools in heterozygous genotypes at the corresponding locus. Let us further consider the role of the mutational process in evolution.

General information

Mutational process - hereditary suddenchange, provoked by a sharp functional and structural transformation of genetic material. The latter is organized into a hierarchy of various elements: from the molecular sites present within the gene, to the chromosomes and genomes. The mutational process is a factor of pressure on the population. As a consequence, the frequency of one allele changes with respect to the other.

Positive effect

Due to the presence of mutant alleles in the gene poolin the heterozygous genotype, a direct negative effect on the phenotypic expression of the trait that is controlled by the gene is excluded.

Due to the hybrid power (heterosis), many mutations in the heterozygous state often contribute to an increase in the viability of the organism.

By storing alleles that are nothave an adaptive value in the real environment of existence, but are able to acquire it either in the future, or in the development of other ecological niches, a reserve of volatility is being formed.

The significance of the mutation process

Importance is due to the fact that with constantthe emergence of spontaneous changes and their combinations when crossing new combinations of genes and transformations. This, in turn, inevitably leads to hereditary adjustments in the population. Role mutation process is to increase genetic heterogeneity. At the same time, without the participation of other factors, he is unable to direct the transformation of the natural population.

The mutational process is the source elementary material, reserve of volatility. The appearance of transformations has a statistical and probabilistic character. The evolutionary significance of the process lies in the maintenance of high heterogeneity of natural populations, participation in the formation of various alleles and the emergence of new genes. The mutational process creates a full range of variability of a particular gene pool. With his constant flow, he has an undirected and random character.

Specificity

Mutational process occurs throughout the life of the whole life. Some transformations can occur many times in different organisms. Genofunds are under the constant influence of the mutational process. This compensates for the high probability of a single change in the number of generations. Although mutational process has relatively little pressure on a single gene, with a large number of the latter, the genetic structure undergoes significant changes.

Mechanism and result

As a result of continuous crosses,many combinations of alleles. The genetic combinatorics repeatedly explores the significance of mutations. They penetrate into new genomes, appear in various genotypic environments. The potential number of such combinations of genetic material within any population is enormous. However, only a negligible fraction of the theoretically probable number of variants is realized. The uniqueness of almost every individual is determined by the realized proportion of combinations. This factor is extremely important for the implementation of natural selection.

Features of manifestation

Mutations are an elementary materialevolution. There are several types: genomic, chromosomal, gene. Among the features of the manifestation of mutations should be highlighted their expressiveness. It reflects the degree of their phenotypic expression. In addition, mutations are characterized by penetrance. It is the frequency of phenotypic manifestations in one allele of a particular gene in a population, regardless of expressiveness.

Gene mutations

They represent a transformationnucleotide sequence. The mutational process in this case changes the nature of the action of the gene. Usually there is a molecular transformation that causes a phenotypic effect. Suppose that in a particular gene at a particular point in the codes there is a CTT coding for glutamic acid. When replacing only one nucleotide, it can become a GTT codon. He will participate in the synthesis of non-glutamic acid, and glutamine. The initial and mutant protein molecules are different, and probably this will lead to secondary phenotypic differences. Exact replication of the new allele will occur until a new change occurs. In the case of a gene mutation, a series or pair of homologous elements thus occurs. You can do the opposite. The presence of allelic variability for one or another gene means that it was mutated at a certain time.

Additionally

The heterozygous condition, the diploid genotype,"silent DNA" - all these are traps for mutations. With the degeneracy of the genetic code, the rarity of the appearance of transformations is indicative of reparation. Mutational processes must occur in existing living organisms with a certain frequency. It should be sufficient to cause changes through which populations are brought to a new level. Mutations are found in various concentrations. Some of them should participate in the historical process of development of living organisms, contributing to the formation of new taxa. Mutations, as a rule, appear without transitions, discretely and spasmodically. The change that appears once is stable. It is passed on to the descendants. Mutations arise not directed. The same change can be repeated many times.

Adaptive value

Most of the new mutants are differentsignificantly lower viability than the wild / normal type. In this case, it is expressed in varying degrees: from the subvital to subtle to semi-lethal and lethal state. In analyzing the viability of the mutant fly flies, which appeared with changes in the X chromosome, in 90% of the individuals it was lower than in the normal ones. At 10% there was a supernital condition - increased viability. In general, the adaptive value of the mutants that appear is, as a rule, reduced. It is characterized by the functional usefulness of morphological features and fertility, physiological viability.

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