The gene pool of a population is a general definition that describes the complex of all its data. For the first time, the concept and the term itself were formulated by the Soviet geneticist Serebryakov in 1928.
Encoding and transmission of information
Each biological species contains a certain chromosome set. So, cats have 19 pairs of chromosomes, a butterfly has 190, a clover has 7, and a person has 23. In the latter case, there is one pair of sex chromosomes. The remaining 22 are directly responsible for the preservation of the gene pool, recombinant and reproductive functions. Sex chromosomes provide the direct process of evolution. They are responsible for changing the population's gene pool.
Chromosomes
They are represented as a sequence of genes that are separated by space. It includes regulatory fragments and DNA regions that do not contain encoded information. The location of genes in chromosomes is uneven. Thus, zones rich and poor in these elements are found. Scientists have not yet been able to pinpoint the reasons for this strange location. Today, the human gene pool is very large. In simple organisms, it is much smaller. Thus, the human gene pool has about 28,000 genes.
Nature of information
Chromosomes carry a large amount of data: skin type, eye color, limb length, nail shape, predisposition to pathologies, blood type, taste habits, and so on. These internal or external characteristics can manifest themselves in the present or future generations. It is believed that hereditary information also includes a person's temperament. But at the moment this assumption is very controversial.
Under the influence of unfavorable conditions or over time, genes can be transformed - in them "breakdowns" occur, which cause chromosomal diseases. These include, for example, Kleinferter's, Down's, Shereshevsky-Turner's syndromes and others. The older the parents are, the greater the likelihood of such mutations. In this regard, at the modern level of development of science, the question of how it is possible to protect the gene pool of a population has become relevant.
Key concepts
In science, three definitions are used that are associated with encoded information: genome, gene pool and genotype. Let's consider the differences between these concepts. The complex of data of an organism inherent in him as a representative of Homo sapiens is defined as a genome. The gene pool characterizes the totality of information of all kinds - all people on the planet. Each individual also has a certain set of information. It is called a genotype. Scientists now have much more knowledge about DNA than they did several decades ago. In this regard, the genome today means the total DNA of the haploid chromosome set and each extrachromosomal element contained in a separate germ cell of a complex organism. The original term was introduced to science in 1920 by Hans Winkler.
Distinctive features of the gene pool
This concept today describes more than 6 billion representatives of Homo sapiens. They are all subdivided into nationalities, nations, races, ethnic groups, nationalities. The gene pool is a special system of characteristics. It has the following features:
- Integrity.
- Dependence on previous generations.
- Genotype heterogeneity.
Among other things, people are characterized by a certain amount of hereditary diseases, which is associated with a high predisposition and a relatively short life. This, in fact, is the basis of natural selection within the population of the planet. The gene pool is one of the most important components of species transformations.
Equilibrium
The frequency with which various alleles are found in a population is determined by the regularity of mutations and the influence of selection. In some cases, the indicator depends on the nature of information exchange during migration. With comparative constancy of conditions and large numbers, the above processes lead to relative equilibrium. As a result, the gene pool of these populations is balanced. Within it, a constancy of the frequency with which different alleles occur, or equilibrium is established.
Imbalance reasons
With natural selection, the change in the gene pool has a directional character. This means that the frequencies of the "payload" data are increased. As a result, microevolutionary transformations take place. However, the transformations that the gene pool undergoes are far from always directed processes. They are often random. As a rule, they are caused by fluctuations in the total number of all species or with the isolation of a certain part of organisms in space. The main reasons causing the transformations that the gene pool undergoes are:
- Migration.
- Separation of species.
- Natural disasters.
Migrations
They represent the movement of some species of one population to a new habitat. If some small part of plants or animals settle in a new area, then their gene pools will inevitably be less than that of their parents. Under the influence of random reasons, the frequency of alleles of the new population may not coincide with those for the original. The data, which were rather rare before the migration, can begin to spread very intensively (due to sexual reproduction) among the migrated individuals. At the same time, genes that were previously present in large numbers may be completely absent. This situation, in particular, takes place if the founders of the new community did not have them.
Separation of views
A situation similar to the one described above can arise when two unequal parts are formed in a population or artificial barriers appear. For example, a dam was built on the river. She divided the fish population inhabiting the reservoir into unequal parts. In a small community, again, due to random reasons, the data set may differ in its composition from the information inherent in the original set of species. In this case, the gene pool will carry only those genotypes that were chosen by chance among a small number of founders of the new group. In this case, previously rare alleles in the educated community can become common.
Natural disasters
They have a significant impact on the composition of the gene pool. As a result of natural disasters, only a few representatives of a particular community manage to survive (for example, after a drought, fire, flood). In a population that survived the cataclysm, which consists of randomly survived individuals, the composition of the gene pool will also be selected non-directionally. After a sharp decline in numbers, active reproduction of the remaining representatives will begin, even forming a small group. Its genetic makeup will determine the structure of the population during its heyday. In such a situation, some mutations may completely cease to exist, and the intensity of other transformations will sharply increase. The gene set that is present in a small surviving group may differ to some extent from that in the original population before the disaster.
Results of numerical fluctuations
Changes in the quantitative composition of the population, regardless of the reasons that caused it, affect the frequency of alleles. With the formation of unfavorable conditions and a decrease in the number due to the death of individuals, the loss of some, especially rare genes may occur. In general, the smaller the quantitative composition, the higher the likelihood of loss and the greater the impact on the formation of the community will have random factors. Fluctuations in numbers periodically occur in almost all organisms. They change the gene frequency in populations that replace the previous ones. Such phenomena are especially evident among insects. Few of them can survive the winter. As a result, their population is significantly reduced by the spring. This small group gives rise to a new insect community. Often, the gene pool of a new population has significant differences from the one that was a year ago.
Natural selection
It provides targeted changes in the gene pool. Natural selection contributes to a sequential increase in the frequencies of some (useful under specific conditions) data and a reduction in others. As a result, those genes that favor the survival of members of the community in a given habitat are fixed in the population. Their share is increasing, and the general composition of data is also transforming.
The gene pool of a population is a set of genotypes of all individuals that make up one population, including all the diversity of the genes of this population. The sum of the gene pools of populations constitutes the gene pool of the species. Interpopulation differences (the originality of the gene pool of each of the populations) are determined not only by the set and frequencies of alleles of genes that make up the genotypes of individuals, but also by the features of intergenic interactions caused by the combination of these alleles in genotypes. New alleles in the population appear due to mutations and since most of the newly emerged alleles are recessive, they do not manifest themselves in the phenotype, but remain in a heterozygous state in the course of generations, contributing to the creation of genetic diversity in the population. The level of heterozygosity varies widely.
Recessive mutations are not the only source of gene pool diversity. Combinative variability plays an important role. During sexual reproduction, random combination of gametes and crossing over provide a unique combination of alleles that make up the genotype of each individual.
Thus, among organisms that reproduce sexually, there are no two individuals with identical genotypes. Identical twins were considered an exception, but they are not genetically completely identical either.
There are a number of characteristics of the population gene pool: the Hardy-Weinberg rule, gene drift, migration, and crossing systems.
Hardy - Weinberg rule.
One of the characteristics of the population gene pool, which makes it possible to compare the gene pools of populations of the same species, can be the analysis of changes in the concentration of alleles of a particular species.
The rule Hardy - Weinberg states: in a large panmictic population, in the absence of disturbing influences, such as repeated mutation of a given gene, selection or selective migration, the concentration of alleles from generation to generation remains unchanged.
The simplest crossing system is panmixia (hence the name of the population), in which any two individuals of a given population are equally likely to interbreed.
Deviation from the rule Hardy - Weinberg s indicates that the population is affected by any of the external factors or their combination (for example, as a result of emigration or immigration of individuals, the populations exchange alleles with other populations of the same species, or a mutation of the same gene has occurred, or according to the trait in the formation of which this gene takes part, selection is in progress).
Two important points follow from the rule:
The concentration of a given allele can only change under the influence of factors external to the population that affect its size and composition.
Different alleles will accumulate in the population - the diversity of alleles will increase with mutation.
This genetic diversity is a characteristic of the gene pool and is of great importance for evolution, because is a selection material.
Allele frequencies change only under the influence of forces external to the population's gene pool. The only exception is gene drift - a stochastic change in the concentration of alleles due to the randomness of crosses in a limited population.
Gene pool - the totality of all genes or genotypes in a population or a group of populations of any kind of organisms. The gene pool of a fairly large population, in which organisms are freely crossed, has a certain integrity and stability: the frequencies of occurrence of certain genes (alleles) and genotypes are maintained in the population in relative equilibrium. However, if the population is exposed to the action of the so-called. elementary factors of evolution (mutations, isolation, natural selection, etc.), this equilibrium is disturbed. Over time, a sustained change in gene frequencies (microevolution) can give rise to speciation.
The term "gene pool" is used not only in relation to natural populations. For example, they talk about the gene pool of any breed of domestic animals, varieties of cultivated plants, or about the gene pool of all breeds and varieties. The need to preserve the gene pool of all living beings on the Earth follows from the recognition of the genetic uniqueness, the uniqueness of biological species, each of which is the result of long evolution.
The study of the gene pool of mankind is important for solving many problems in anthropology and medicine.
Each biological species is a collection of individuals similar in basic morphological and functional characteristics, karyotype, behavior, having a common origin, interbreeding in natural conditions exclusively with each other and at the same time producing fertile offspring. The most important features of a species are its genetic (reproductive) isolation, which consists in non-breeding of individuals of this species with representatives of other species, as well as genetic resistance in natural conditions. But at the same time, all species are highly dynamic, manifested in intraspecific variability, the formation and decay of intraspecific groups of various sizes and composition (populations, races, subspecies). Currently, scientists have identified a complex genetic structure of the species.
In nature, individuals of the same species are distributed unevenly. As a result, the species splits into separate groups - populations. A population is a collection of freely interbreeding individuals of the same species living in a certain area. Each population is more or less isolated from other populations of the same species. The gene pool of a species, in fact, splits into gene pools of populations, each of which differs in a different direction of variability. The most important characteristic of a population's gene pool is the frequencies of individual alleles and genotypes.
The populations of dogs living on the globe are very diverse. These are populations of wild, or rather feral, animals; and dog populations of large cities or small towns; and pedigree animal populations of individual nurseries. The populations of the individual nurseries together constitute the population of a club, and the populations of the clubs constitute the population of the city. Populations of different cities of Russia form the population of Russia, etc. Each population will consist of a different number of animals, have a different sex, age and spatial structure.
Interpopulation migrations of individuals, no matter how insignificant they are, prevent the deepening of differences and unite populations into a single system of the species. However, in the case of prolonged isolation of some populations from the rest of the species, the initial minimal differences increase and may ultimately lead to the formation of a new species. Thus, the population is an elementary evolving unit.
With little changing habitat conditions, the preservation of a species over time depends on the stability of its gene pool. On the other hand, stable gene pools do not ensure survival when living conditions change.
All animal populations are highly genetically heterogeneous. This has tremendous implications for evolution. Schmalhausen (1969) called the presence in populations of a huge reserve of latent variability not manifested in the phenotype and inaccessible for selection as a mobilization reserve of variability. Under certain conditions, for example, with a sharp change in living conditions, epidemics, this reserve can be used in the evolutionary process.
The gene pools of populations are under continuous pressure from the constantly occurring mutational process, which serves as the main supplier of variability and plays the role of an elementary evolutionary factor.
Chetverikov (1926) wrote that "a species absorbs mutations like a sponge, while itself remaining phenotypically homogeneous." Indeed, most of the mutations that arise are recessive, and at a sufficiently high population size, they seem to dissolve, finding themselves in a heterozygous state and not manifesting themselves in the phenotype. They can accumulate in the population's gene pool and persist in it for an arbitrarily long time, hiding from the action of selection. In addition to recessiveness, there are a number of other genetic mechanisms that make it possible to neutralize the manifestation of mutations that are harmful under the given conditions: epistasis, pleiotropy, the action of modifier genes, and incomplete penetrance. An important component of the population reserve of hereditary variability is neutral mutations, which, although they do not manifest themselves in the phenotype, for the time being do not affect the fitness of their carriers. The reserve of genetic variability also includes conditionally harmful or conditionally beneficial mutations. Their effect is manifested only under certain conditions, and selection either decreases or increases their frequency, which leads to the constant presence of such mutations in the gene pool of populations. Mechanisms for leveling variability do not arise by themselves, but are formed in the course of evolution under the influence of selection.
The genetic unity of a population is determined by a sufficient level of panmixia, that is, equiprobable crossing of individuals with each other. Under conditions of a random selection of crossing individuals, the source of alleles for the genotypes of organisms of successive generations is the entire gene pool of the population.
GENO FUND GENO FUND
(from gene and French fond - base), a set of genes that individuals of a given population, group of populations or species have. The term "G." introduced by AS Serebrovsky in 1928. The basis of genetic engineering. the integrity of the population is the presence of a sexual process, which ensures the possibility of constant exchange within its inheritance, material. As a result, a single G. of the population is formed, where in each generation individuals of a different genotype make a greater or lesser contribution, depending on their adaptability, value. The most important feature of a single G. is its deep differentiation and heterogeneity. G. and attributes, the frequencies of genotypes in a number of generations could remain constant if: the size of the population is so large that the drift of genes is weakly expressed; no elects. mutations in Ph.D. direction; no differentiation occurred. selection of genotypes; there is no migration or migrants are heotypically identical to local individuals. The presence of one of these factors in nature changes the frequencies of genes in G. and, as a result, changes the balance of the frequencies of genotypes. Different types have a decomp. G., and it is natural to assume that factors that change the frequencies of certain genes in a population can be considered basic. reasons for the formation of species. It is assumed that the formation of higher taxonomy categories than a species (i.e., the entire biological evolution) is based, like speciation, on changes in G. The protection of natural sciences and arts, plant and animal populations is one of the center tasks of conservation. wildlife.
.(Source: "Biological Encyclopedic Dictionary." - M .: Sov.Encyclopedia, 1986.)
genofondThe collection of all genes or genotypes in a population or group of populations of any kind of organism. The gene pool of a sufficiently large population, in which free crossing of organisms occurs, has a certain integrity and stability: the frequency of occurrence of certain genes ( alleles) and genotypes are maintained in the population in relative equilibrium. However, if the population is exposed to the action of the so-called. elementary factors of evolution ( mutations, isolation, natural selection and others), this equilibrium is disturbed. Over time, a stable change in gene frequencies ( microevolution) can give an impetus speciation.
The term "gene pool" is used not only in relation to natural populations. For example, they talk about the gene pool of any breed of domestic animals, varieties of cultivated plants, or about the gene pool of all breeds and varieties. The need to preserve the gene pool of all living beings on the Earth follows from the recognition of the genetic uniqueness, the uniqueness of biological species, each of which is the result of long evolution.
The study of the gene pool of mankind is important for solving many problems in anthropology and medicine.
.(Source: "Biology. Modern illustrated encyclopedia." Ed. A. P. Gorkin; Moscow: Rosmen, 2006.)
Synonyms:
See what "GENOFUND" is in other dictionaries:
The gene pool ... Spelling dictionary-reference
- (from genes and French fond base), the totality of all genes of a given population, a group of populations or a species as a whole. The gene pool of flora and fauna (with the exception of the gene pool of dangerous pathogens) is subject to protection, which should ... ... Ecological Dictionary
Modern encyclopedia
Gene pool is a concept from population genetics that describes the totality of all gene variations (alleles) of a given population. The population possesses all of its alleles for optimal adaptation to the environment. You can also say ... Wikipedia
1) in genetics, the general composition and number of genes of all individuals that make up the population, the type of microorganisms or other living beings; 2) in ecology, the entire set of species of living beings either on a planetary scale, or in its individual regions, ecosystems. ... ... Microbiology Dictionary
Gene pool- (from gene and French fond base), a set of genes that are in the individuals that make up a given population. Emphasizing the need to preserve all living species, they also talk about the gene pool of the Earth (biosphere). Methods are being developed ... ... Illustrated Encyclopedic Dictionary
- (from gene and French fond base) a set of genes that are present in the individuals that make up a given population. Emphasizing the need to preserve all living species, they also talk about the gene pool of the Earth (biosphere). Methods are being developed ... ... Big Encyclopedic Dictionary
GENOFUND, all possible genes and their various ALLELS that exist in all representatives of each specific species at the moment. For species to be made strong and surviving, the gene pool must be large enough to ... ... Scientific and technical encyclopedic dictionary
Nus., Number of synonyms: 1 set (29) ASIS synonym dictionary. V.N. Trishin. 2013 ... Synonym dictionary
Gene pool. See gene pool. (Source: "The English Russian Explanatory Dictionary of Genetic Terms." Arefiev VA, Lisovenko LA, Moscow: VNIRO Publishing House, 1995) ... Molecular biology and genetics. Dictionary.
Books
- Gene pool and population genogeography. Volume 1. The gene pool of the population of Russia and neighboring countries,. An exhaustive summary of the available in the literature and new data on the distribution of frequencies of genes and phenotypes for all genetic studies in the population of Russia and neighboring countries is presented ...
- Gene pool and population genogeography. Volume 2. Genogeographic Atlas of the Population of Russia and Neighboring Countries,. The second volume of the multivolume edition "Gene Pool and Genogeography of Population" prepared by a team of authors for the first time presents a genogeographic atlas of the population of Russia and adjacent ...
The gene pool of a population, even if it is phenotypically homogeneous, is a heterogeneous mixture of different genotypes. Any changes in the gene pool affect the frequencies of occurrence of different alleles, and hence genotypes. A decrease or increase in the frequency of occurrence of individual genotypes can be caused by the death of individuals as a result of natural fluctuations in the population size, migration of individuals from one population to another, the emergence of new mutations, and their combination during crossing. Due to the action of these processes in the population, some genotypes continuously arise, others disappear, the concentration of the third changes in one direction or another. The gene pool of the population can be figuratively represented as "the undulating surface of the sea, which is never lifelessly calm, even in the most complete calm."
However, a situation may arise in a population when it will experience stronger and more prolonged pressure from some external factors (for example, the frequency of mutations increases dramatically). This can lead to a significant and irreversible change in the gene pool for a long period of time, i.e. To