Humanity is characterized by a high level of hereditary diversity, which is manifested in a variety of phenotypes. People differ from each other in the color of their skin, eyes, hair, the shape of the nose and ear, the pattern of epidermal ridges on the fingertips and other complex characteristics. Numerous variants of individual proteins have been identified, differing in one or more amino acid residues and, therefore, functionally. Proteins are simple traits and directly reflect the genetic constitution of an organism. People do not have the same blood groups according to the erythrocyte antigen systems “Rhesus”, AB0, MN. More than 130 variants of hemoglobin are known, and more than 70 variants of the enzyme glucose-6-phosphate dehydrogenase (G6PD), which is involved in the oxygen-free breakdown of glucose in red blood cells. In general, at least 30% of the genes that control the synthesis of enzymes and other proteins in humans have several allelic forms. The frequency of occurrence of different alleles of the same gene varies.

Thus, of the many hemoglobin variants, only four are found in high concentrations in some populations: HbS (tropical Africa, Mediterranean), HbS (West Africa), HbD (India), HbE (South-East Asia). The concentration of other hemoglobin alleles everywhere apparently does not exceed 0.01-0.0001. The variability in the prevalence of alleles in human populations depends on the action of elementary evolutionary factors. An important role belongs to the mutation process, natural selection, genetic-automatic processes, and migrations.

The mutation process creates new alleles. And in human populations it acts undirectedly, randomly. Because of this, selection does not lead to a pronounced predominance of the concentration of some alleles over others. In a sufficiently large population, where each pair of parents from generation to generation produces two offspring, the probability of maintaining a new neutral mutation after 15 generations is only 1/9.

The entire variety of protein variants, reflecting the diversity of alleles in the human gene pool, can be divided into two groups. One of them includes rare variants that occur everywhere with a frequency of less than 1%. Their appearance is explained solely by the mutation process. The second group consists of variants found relatively frequently in selected populations. So, in the example with hemoglobins, the first group includes all options except HbS, HbC, HbD and HbE. Long-term differences in the concentration of individual alleles between populations, the preservation of several alleles in a sufficiently high concentration in one population, depend on the action of natural selection or genetic drift.

A stabilizing form of natural selection leads to interpopulation differences in the concentration of certain alleles. The non-random distribution of alleles of erythrocyte antigens AB0 across the planet may, for example, be due to the different survival rates of individuals differing in blood type in conditions of frequent epidemics of particularly dangerous infections. The areas of relatively low frequencies of the I 0 allele and relatively high frequencies of the I B allele in Asia approximately coincide with the plague foci. The causative agent of this infection has an H-like antigen. This makes people with blood type O especially susceptible to plague, since they, having the H antigen, are not able to produce anti-plague antibodies in sufficient quantities. This explanation is consistent with the fact that relatively high concentrations of the I 0 allele are found in the populations of the aborigines of Australia and Polynesia, and American Indians, who were practically not affected by the plague.

The incidence of smallpox, the severity of symptoms, and mortality are higher in persons with blood group A or AB compared to persons with blood group 0 or B. The explanation is that people of the first two groups do not have antibodies that partially neutralize the smallpox antigen A. People with blood type 0 are on average able to live longer, but they are more likely to develop peptic ulcers.

At the same time, for populations from the same geographical area, but reproductively isolated, the cause of differences in the concentration of ABO alleles could be genetic drift. Thus, the frequency of blood type A reaches 80% among the Blackfoot Indians, and 2% among the Utah Indians.

The persistent persistence of several alleles of one gene in the human population at the same time is, as a rule, based on selection in favor of heterozygotes, which leads to a state of balanced polymorphism. A classic example of this situation is the distribution of hemoglobin S, C, and E alleles in foci of tropical malaria.

Above are examples of polymorphism at specific loci, which is explained by the action of a known selection factor. Under natural conditions, due to the influence of a complex of factors on the phenotypes of organisms, selection is carried out in many directions. As a result, gene pools are formed that are balanced in the set and frequencies of alleles, ensuring sufficient survival of populations under these conditions. This is true for human populations as well. Thus, people with blood group 0 are more susceptible to plague than people with group B. Pulmonary tuberculosis is treated with greater difficulty in them than in people with blood group A. At the same time, treatment of people with syphilis with blood group 0 causes the disease to progress more quickly into an inactive stage. For individuals with blood group 0, the likelihood of developing stomach cancer, cervical cancer, rheumatism, coronary heart disease, cholecystitis, and gallstone disease is approximately 20% lower than for individuals with group A.

Genetic polymorphism at many loci could be inherited by people from their ancestors at the presapient stage of development. Polymorphism in such blood group systems as AB0 and Rh has been found in great apes. The selection factors that created the current picture of the distribution of alleles in the human population have not been precisely established for the vast majority of loci. The examples discussed above indicate their ecological nature.

Genetic polymorphism is the basis of interpopulation and intrapopulation variability in people. Variability is manifested in the uneven distribution of certain diseases around the planet, the severity of their occurrence in different human populations, different degrees of susceptibility of people to certain diseases, individual characteristics of the development of pathological processes, and differences in response to therapeutic effects. Inherited diversity has long been an obstacle to successful blood transfusion. Currently, it creates great difficulties in solving the problem of tissue and organ transplants.

Living organisms within a population vary. Alleles determine different traits that can be passed on from parents to offspring. Changing genes is important for the process.

The genetic diversity that occurs in a population is random and there is no process of natural selection. Natural selection results from the interaction between genetic diversity in a population and the environment.

The environment determines which options are more favorable. Thus, more favorable traits are passed on to offspring in the future.

Causes of genetic diversity

Genetic diversity occurs mainly due to DNA mutation, gene flow (the movement of genes from one population to another), and. Because the environment is unstable, populations that are genetically variable will be able to adapt to changing situations better than those that do not contain genetic diversity.

• DNA mutation: it is a change in the DNA sequence. These types of sequences can sometimes be beneficial to organisms. Most mutations that lead to genetic changes cause traits that are neither beneficial nor harmful.
• Gene flow: also called gene migration, gene flow introduces new genes into a population as organisms migrate to different environments. New combinations of genes are made possible by the presence of new alleles in the gene pool.
• Sexual reproduction: promotes genetic change by producing different combinations of genes. is the process by which or are created. Genetic variation occurs when alleles in gametes separate and randomly combine during fertilization. Genetic recombination of genes also occurs when gene segments cross or break during meiosis.

Examples of genetic diversity

A person's skin color, hair color, different colored eyes, dimples and freckles are all examples of genetic variations that can occur in a population. Examples of genetic changes in plants include modified leaves and the development of flowers that resemble insects to lure pollinators.

This subsection is devoted to the biopolitical aspects of human genetic diversity. This problem can be considered in the context of the genetic diversity of bios as a whole (cf. above 3.2.). It is known that every internal heterogeneous the system has an additional reserve of stability. Therefore, biopolitician V.T. Anderson added his voice to all those protesting against the cultivation of a few, or even worse, one variety of agricultural plants on a planetary scale (Anderson, 1987). Anderson considered the passion for cultivating corn varieties of the same genotype, although sold under different varietal labels, to be one of the reasons why among the corn plants there were not enough resistant to the diseases that affected American agriculture in the 70s. Erosion (depletion) of the gene pool of cultivated plants and domestic animals, depletion of the gene pool of the biosphere as a whole is a global problem, the solution to which includes political facilities. It is necessary to develop international legislation on the creation of gene banks (for example, in the form of samples of plant seeds of different varieties and species), on measures against the Western monopoly on storage, patenting, sale on the international market of plant varieties and animal breeds and on the protection of the rights of Third World countries, where the plant and animal gene pool is richest.

An integral part of a diverse and at the same time internally unified bios (“bios body” according to the President of the Biopolitical International Organization A. Vlavianos-Arvanitis) is humanity, heterogeneous genetically and phenotypically diverse - in appearance and physiological, psychological, behavioral characteristics. It is through the diversity of individual options that the unity of humanity is manifested as an integral part of the planetary “body of bios”. It is known that humanity, like any system, gains in sustainability due to diversity, including genetic diversity. Even traits that cause negative consequences under given conditions can be beneficial. changed situation. The diversity of gene pools contributes to the survival of society.

This can be demonstrated with an example sickle cell anemia- a hereditary human disease caused by a point mutation (replacement of one base pair in DNA). The mutant gene encodes defective polypeptide chains of hemolobin, a blood protein that transports oxygen. As stated above, genes are represented in two copies in the body. If both hemoglobin genes are mutated, a severe, often fatal form of sickle cell anemia occurs due to insufficient oxygen supply. However, an individual with mixed genes (one normal and one mutant copy) has enough normal hemoglobin to survive and, in addition, has the advantage of being more resistant to tropical malaria than an individual without this mutation. Therefore, in those regions of the world where malaria is widespread, this mutation. may be seen as beneficial, and for this reason it may spread throughout the population.

However, the fact of the genetic diversity of mankind evokes an ambivalent attitude towards itself. Not everyone shares the bright, rosy idea that “every /human individual/ is beautiful,... diversity is wonderful.” (these lines were written by F. Rushton with sarcasm). Why do people not like genetic diversity? What biopolitical problems does it raise? Let's look at these problems.

6.3.1. Individual variations. The myth of the genetic community of nations. The high degree of human genetic polymorphism at the individual level concerns various categories of its characteristics - from hair and eye color to biochemical factors and behavioral characteristics (to the extent that the latter are genetically fixed, see above). A good illustration of gene polymorphism is the diversity of systems tissue compatibility (histocompatibility)HL-A, which in general allow for over one and a half million options (Khrisanfova, Perevozchikov, 1999).

The question still remains debatable to what extent the mutual attraction of people (friendship, marriage, cooperation in the same political organization, etc.) is dictated by the subconsciously assessed similarity of tissue compatibility systems or other genetically determined parameters. Are we similar to mice, whose histocompatibility systems are similar in individuals of the same biosocial system and differ in individuals from different such systems? Philip Rushton insists on the important role of similar genes when choosing a friend, spouse, partner, moreover, he considers it one of the main mechanisms for the formation of ethnic groups (tribes, nations, etc.); Other authors dispute the importance of these factors, believing that, for example, a nation is the result of a “fictitious kinship” (Masters, 1998), a common misconception among a group of people about its origin (Anderson, 1987), and national identity is the fruit of political indoctrination of people (see Section 5). Indeed, a lot of genetic data testifies to the very significant heterogeneity of most nations, which does not allow us to talk about a significant “genetic community” of their representatives. This is also in accordance with the data of phenotypic studies - the study of anthropological types that coexist within each nation.

6.3.2. Genetic abnormalities. Individual genetic diversity raises issues with political and ethical dimensions regarding so-called “genetic abnormalities” and, by extension, the concept of “normal.” For example, which individual genetic characteristics should society treat or eliminate? In the previous subsection, we already talked about subclinical, socially adaptable forms of schizophrenia and manic-depressive psychosis. Are they, albeit “erased,” but still a pathology (and then the question of limiting childbearing, therapeutic measures, etc. can be raised) or are they still acceptable options for the psyche and behavior, moreover, carrying a number of socially valuable qualities. It is no secret that many talents, and especially geniuses, had obvious mental “anomalies”, which, for example, allowed them to see connections between things that were inaccessible to the “average man in the street.” One of the tests for predisposition to schizophrenia is precisely based on the ability to group objects according to properties that are not noticeable to “normal people”!

Some anomalies undoubtedly cause serious consequences for the health and life of the individual, such as progeria– premature aging, which occurs already in 8-10 year old children! However, in a number of other cases, the very concept of “genetic abnormality” causes serious problems. Before defining “deviation from the norm”, it is necessary to define the concept of “norm”, which is very problematic. As the sickle cell anemia example above shows, even apparently harmful abnormal features can be beneficial in certain conditions (sickle cell anemia - when tropical malaria is common). What about “anomalies” that do not cause medical problems, such as polydactyly(6-7 fingers and toes), which may cause social rejection as “deformities” or be viewed positively as an “interesting feature” of an individual? After all, six-fingered (and even more so seven-fingered) individuals can play chords of 12 or 14 notes that are inaccessible to ordinary people and, perhaps, master special computer keyboards suitable only for them or weapon systems with a large number of buttons. Aren't six-fingered people a special minority that in democratic countries like the USA can claim their political rights (like lesbians or people with disabilities)! Will the polydactyls (and not only them) decide that they represent an evolutionary-progressive form, in relation to which we are something like archanthropes? AND Who have the right to challenge such a decision? Such problems inevitably stand in the way of eugenics, see next. subsection).

Let us emphasize once again that individual diversity is only partially determined by genetic polymorphism. To a very large extent, people are different “externally and internally” due to differential impact of environmental factors on them. Even brothers (including genetically identical twins) in the same family are still not raised exactly the same: they are treated somewhat differently, which causes differences in terms of learning ability, personality traits, and pathological deviations that exist even between twins.

6.3.3. Eugenics is a set of social programs to improve the genetic fund of humanity (from the Greek words: eu - “good”, genesis - “origin”). The English scientist Francis Galton, the founder of eugenics, is known primarily for his works “On the Heredity of Talent” (1864), “The Heredity of Talent, Its Laws and Consequences” (1869), etc. An analysis of the biographies of prominent people led him to the conclusion that abilities are genetically determined and talents. They were tasked with improving the heredity of mankind by selecting useful qualities and eliminating harmful ones, which is the essence of eugenics. Similar views were expressed in Russia by medical professor V.M. Florinsky (Tomsk University) in the book “Improvement and Degeneration of the Human Race” (1866). Subsequently, the eugenics movement spread in different countries.

Eugenic measures are based on selection methods. Eugenics is divided into positive(stimulating the spread of beneficial genotypes) and negative(setting up barriers to the spread of harmful hereditary factors in society). Both options may vary in the degree of severity of the relevant measures. Negative eugenics can be manifested by limiting consanguineous marriages and creating medical and biological consultation centers that inform people about the undesirable possible consequences of certain family connections. In a more severe version, negative eugenics involves limiting the reproductive function of people with undesirable genes (mental patients, alcoholics, criminals) up to sterilization. Positive eugenics involves creating favorable conditions for childbearing for selected (noble birth, physically healthy, beautiful, talented, etc.) members of society through material and moral incentives. She may try to set a large-scale task of breeding a new person by selecting genotypes obtained in the offspring of people who have outstanding qualities. Negative eugenics was put into practice at the beginning of the twentieth century in the USA, Germany, Sweden, Norway and other countries in the form of laws on the sterilization of certain groups of individuals (for example, with mental pathology).

“Russian Eugenics Society”, created in 1920 and including prominent geneticists: N.K. Koltsova (chairman), A.S. Serebrovsky, V.V. Bunak and others, rejected negative eugenics and took up positive eugenics. Outstanding geneticist Herman Meller, author of the letter to I.V. Stalin in support of positive eugenics, advocated a “crusade” in favor of eugenic measures. The subsequent development of foreign and domestic science led to a significant cooling of interest in eugenics, which was also due to political reasons. Eugenics in Germany was tainted by connections with the Nazi regime; in the USSR, persecution of genetics T.D. Lysenko and his supporters, among other arguments, covered themselves with references to the inhumane nature of eugenics, especially negative ones.

Despite all this, it is too early to consign eugenics to the history museum these days. It is being revived with the receipt of new scientific data about real the contribution of hereditary factors (let us not forget, however: this contribution is partial and its implementation largely depends on environmental factors, life experience, see 6.2.) to certain abilities, personality traits, behavioral characteristics, and mental abnormalities of a person. Eugenics is also reviving as new opportunities arise to influence the gene pool of people through artificial insemination, genetic engineering, and in the not so distant future, human cloning. In the 60s of the twentieth century, A. Toffler, in his book “The Third Wave,” asked whether it would be possible to carry out a biological restructuring of people in accordance with professional requirements. In 1968, the famous geneticist L. Pauling proposed introducing mandatory monitoring of the entire population for genetic abnormalities. He proposed marking all carriers of unwanted genes (for example, with a tattoo on the forehead). In the 60s, through the efforts of the American scientist H. Mühler, Sperm bank for Nobel laureates(see Mendelsohn, 2000). Around the same years, A. Somit considered “social policy in the field of eugenics” one of the “troubling problems looming on the horizon” (Somit, 1972, p. 236).

The concern of the luminary of biopolitics was not without foundation. Today, some influential figures in science speak out in support of both positive and negative eugenics. On the pages of the collection “Research in Biopolitics, vol. 5" E.M. Miller presents a case for eugenics as an effort to improve the gene pool of a population. If successful, eugenics promises an increase in the average productivity of workers (who will have outstanding abilities), a decrease in public costs for charity and support for those who cannot earn their own bread, and a decrease in the number of criminals, because crime “has a significant hereditary component.” Miller proposes specific eugenic measures (some of which, he says, are already practiced even in democratic countries): preventing convicted criminals from seeing their wives and girlfriends in order to limit the number of children with “criminal” genes; castrate sexual predators, since their behavior is programmed in their genes; offer to the poor sterilization for a cash bonus of 5-10 thousand dollars, because the qualities that lead to poverty (in particular, the desire for today's pleasures to the detriment of longer-term plans) are also associated with genetic factors. Considering zero population growth to be the optimal demographic situation, Miller advocates for a differentiated attitude towards the reproduction of different individuals - the government should allow the most promising to have up to 3-4 children, and less desirable from a genetic point of view - only one child or dissuade them from childbearing altogether (they say, not only in him is the joy of life). F. Salter and especially F. Rushton, who also consider themselves biopoliticians, are also not far from eugenic views. In recent years, the latest genetic technologies have put on the agenda the question of the possibility "genetic enhancement" of people(see 7.3. below).

Whatever new data on the partial genetic determination of socially important aspects of human individuals are presented by modern eugenicists, they cannot ignore a number of serious objections that have both political and ethical significance:

· Eugenic measures ignore the dependence of human qualities on the environment and life experience. As stated above, the environment determines some differences in the characteristics of even genetically identical twins. N.K. It is not for nothing that Koltsov, in addition to eugenics, also meant “euphenics” - the formation of good qualities or the correction of painful manifestations of heredity in a person by creating appropriate conditions (medicines, diet, education, etc.).

· The question arises, “To what standard should the “improved” breed of man be adjusted? Like a genius, athlete, movie star or businessman? Or maybe something arithmetic mean? Who should decide this issue? If we follow the path of eugenics, then judges will be appointed by dictators, criminal clans and very rich organizations. And there will be a fierce struggle between parties and factions for these judges.

· As stated above, for a population of any given species, the condition for well-being and adaptability to the environment is the preservation of significant genetic diversity. The same is true for human society: its harmonious and sustainable functioning is possible only if it contains people with very different abilities, inclinations and temperaments. Eugenics, when implemented, threatens to erase this natural diversity, perhaps divide humanity into genetic stable castes (“elite” and “anti-elite”, suitable as cannon fodder, for example).

In light of such objections, the more popular idea in modern biopolitics is that medical and genetic counseling V "family planning centers", which does not take away the individual’s freedom of choice in connection with creating a family and childbearing, but allows people to foresee the consequences of certain decisions and obtain information about the strengths and weaknesses of their genotype. The function of family planning centers is to ask people questions, not to make decisions for them. Such “family planning centers” will also help solve many other biopolitical problems (see section 7 of the book).

6.3.4. Racial difference as a biopolitical problem. Let us consider one of the biopolitically important examples of genetic diversity of humanity at the level of groups (subpopulations). It is well known that humanity consists of several races- Equatorial (Negro-Australoid), Eurasian (Caucasoid, Caucasian), Asian-American (Mongoloid). These are the so-called big races; Many classifications divide the equatorial race into Negroid (African) and Australoid (aboriginals and Negritos), and the Asian-American race into Mongoloid (in the narrow sense, Asian) and American (“Indian”) races. There are even more detailed classifications. We will look at racial differences from a genetic perspective.

There is a genetic definition race How large population of human individuals, which have some genes in common and which can be distinguished from other races by the genes they share. It is also known to what extent the concept of “race” is socially and politically significant, how often genetically determined racial differences served as a justification for one form or another. racial discrimination or eugenics concepts. The data of modern genetics, however, are such that many researchers consider the very concept of race (as a criterion for classification) to be of little significance.

The identification of “common genes,” as required by the above definition of race, turned out to be a difficult and unrewarding task. So, if by “common genes” we mean genes that are present only in one race, then these genes are few and have not been sufficiently studied (an example is the genes responsible for vertical fold of the upper eyelid and characteristic only for Mongoloid race). In most of the cases studied, we are not talking about special genes unique to a given race, but only about different frequencies the same genes in different races. So, the enzyme gene lactase, necessary for the digestion of whole milk, occurs much more often in Caucasians than in representatives of the other two races. Of the traits with varying frequencies, many have a clear dependence on environmental conditions. The low content of melanin - the dark pigment of the skin - in Caucasians and Mongoloids compared to the equatorial race is now considered as an adaptation to the conditions of northern latitudes, where solar radiation contains few ultraviolet rays necessary for the synthesis of vitamin D, and light skin transmits a larger proportion of ultraviolet radiation than dark skin .

An important fact that undermines the genetic significance of racial differences is that internal differences between members of the same race often exceed differences between races. According to current estimates, about 85% of genetic diversity is observed inside each of the races, and only a relatively insignificant amount (~15%) accounts for racial differences. Many modern human geneticists are inclined to believe that if in the event of a global catastrophe only one tribe survives in the forests of New Guinea, then almost all the genes (alleles) found in the 4 billion people inhabiting the modern Earth will be preserved.

Some paleontological finds of recent decades, which support ideas about the relatively recent (200-300 thousand years ago) appearance of the species, also speak in favor of the relatively low scientific value of “race” as a concept. Homo sapiens in one geographical area in East Africa (hypothesis monocentrism). However, this issue remains debatable, since there is also a polycentric hypothesis of the origin Homo sapiens from different archanthropes (see above, subsection 3.4.).

Anthropologist L.L. Cavalli-Sforza obtained data on racial differences by studying DNA polymorphisms. Based on data on allele frequencies in many loci (regions) of chromosomes in samples consisting of representatives of different races, it was concluded that there are at least 5 main subpopulations within humanity - Negroids (Africa), Europeans and similar groups of people, Mongoloids (Asia only), American Indians and Autraloids (Australia, Papua). Based on the depth of interracial differences in allele frequencies, different authors have constructed not completely coinciding schemes of the origin of races through dichotomous branching (dividing the common trunk corresponding to ancient man into two branches, these branches in turn into two smaller branches, etc.). Most authors assume that the initially homogeneous human population first divided into Negroids and non-Negroids (for the “tropical trunk” and all others in the classification of V.V. Bunak); further stages of branching vary among different authors. As an example, M. Ney and A.K. Roychaudhary speaks of a further division of non-Negroids into branches Europeans and non-Europeans (in Cavalli-Sforza, “non-Negroids” are divided into the races of Northern Eurasia, where Europeans are already a second-order branch, and into the races of Southeast Asia); non-Europeans split into American Indians and those who gave rise to populations Mongoloids And Australoids. However, the obtained data on allele frequencies can be explained not by the disintegration of the original population into parts, but by random processes of genetic drift, migration, etc., which reduces the value of these data as a basis for interpreting racial differences as historical entities.

Objectively existing racial differences are used to justify, sometimes openly neo-racist views. The already mentioned F. Rushton refers to the differences between the average statistical data among representatives of large races (Caucasoid, Mongoloid and Negroid) in IQ - intelligence quotient (on average 106 in Mongoloids, 100 in Caucasians and 85 in Negroids), brain volume in relation to the volume bodies, etc. All this data is very debatable (for example, many biopoliticians believe that IQ tests were written for representatives of European culture, and Africans are not dumber, but simply do not understand what they want from them). Rushton’s data about the allegedly increased incidence of AIDS among blacks in the United States compared to “whites” is not confirmed by other biopoliticians, in particular, James Schubert.

Finally, the genetic diversity of humanity is now being considered increasingly not in terms of race or group in general, but in purely individual level. The interest of many biopolitics has already been noted in the differences between individuals, even within the same family, caused by genetic diversity, complemented by the differentiating influence of the microenvironment.

So, one of the main research areas of biopolitics studies the influence of a physiological (somatic) state on the political activity of individuals and groups of people. One of the “focal points” of this direction is the role of genetic factors in political behavior. Many human behavioral characteristics and anomalies are characterized by a moderate contribution of genetic factors, i.e. they are formed under the combined influence of genetic and environmental factors. The contribution of genetics to biopolitics is also associated with the study of the genetic diversity of humanity. Many genetic data indicate considerable heterogeneity in most modern nations, so that a nation appears to be the result of a “fictitious kinship,” a common misconception among a group of people about its origins. The question of the importance of racial differences between people remains debatable, but many facts indicate the predominance of individual variations over racial ones in the human population. Systems of measures to stimulate the spread of “favorable” genes in the human population (positive eugenics) and the elimination (culling) of “unfavorable” ones (negative eugenics) - raises significant objections, since it ignores the contribution of environmental factors and leaves the question of criteria and authorities fundamentally unresolved in the matter of “stimulation” and “culling”, and also threatens to reduce the genetic diversity of humanity, which is of significant value and a reserve of sustainability of the human population.

What is genetic diversity?

Genetic diversity refers to the diversity (or genetic variation) within a species.

Each individual species has a set of genes that create its own unique traits. For example, in humans, the enormous diversity of faces reflects the genetic individuality of each individual. The term genetic diversity also refers to the differences between populations within a species, as exemplified by the thousands of dog breeds or the many varieties of roses and camellias.

What is the significance of genetic diversity?

The huge diversity of genes also determines the ability of an individual or an entire population to withstand the adverse effects of a particular environmental factor.

While some individuals are able to withstand relatively high concentrations of pollutants in the environment, other individuals with a different set of genes in the same conditions may lose the ability to reproduce or even die. This process is called natural selection, and it leads to a decrease in genetic diversity in certain habitats. However, these same individuals may carry genes for faster growth or for better resistance to other adverse factors.

How do economic activities affect genetic diversity?

Any changes in the environment, natural or anthropogenic, trigger a selection process in which only the most adapted individuals and taxa survive.

The main anthropogenic factors in the coastal zone are as follows:

artificial selection (harvesting, aquaculture)

habitat destruction (leading to a decrease in population size, which increases the likelihood of inbreeding)

introduction of foreign organisms into nature.

All this reduces the gene pool of the population, which in turn reduces its ability to withstand negative natural or anthropogenic changes in the environment.

Why is it important to confront the loss of genetic diversity?

Loss of genetic diversity is difficult to measure or assess visually. On the contrary, the extinction of populations or a decrease in their numbers is much easier to notice. Extinction is not only the loss of a species as such, it is preceded by a decline in genetic diversity within the species.

This loss reduces the ability of the species to perform its inherent functions in ecosystems.

A decrease in genetic diversity within a species may result in the loss of beneficial or desirable traits (such as resistance to pests and diseases). Reduced genetic diversity could eliminate the potential for these still untapped resources to be used as future food, industrial, or medicinal organisms.

The challenge of maintaining genetic diversity is important for breeders of all dog breeds, but it becomes especially important for breeds with small numbers. The question is: is there enough genetic diversity within a breed population to maintain its health and vitality? Breeders should not forget about genetic diversity, because some breeding tactics that lead to a decrease in it can be harmful to the breed. Reduced genetic diversity can affect the welfare of not only small breeds, but also breeds with large populations.

All genes in the body are present in two copies: one is inherited from the father, the other from the mother. Each copy in such a pair is called an allele. If the alleles in a pair are the same, the gene is called homozygous. If the alleles are different from each other, the gene is called heterozygous. Although any given dog may only have two alleles of each gene, there are usually many different allele variants in a population that can be included in an allelic pair. The greater the number of alleles for each gene pair (this is called gene polymorphism), the greater the genetic diversity of the breed.

If there is no allelic diversity in a particular gene, but the gene is not deleterious, then this situation does not have a negative effect on the health of the breed. Indeed, the characteristics that enable individuals of a breed to produce offspring that meet the breed standard are usually based on immutable (i.e. homozygous) gene pairs.

The history of their founding plays an important role in the genetic diversity of breeds. Generally, working breeds are created using founders from a variety of backgrounds and therefore have significant genetic diversity. Even when experiencing periods of “bottleneck” (a sharp decline in population [approx. per.]), the breed retains a sufficient amount of diverse genetic material. This was shown in a molecular genetic study of the Chinook breed, whose population decreased to 11 individuals in 1981.

Breeds founded by inbreeding into a limited number of related individuals may have reduced genetic diversity. In addition, many breeds went through diversity-reducing bottlenecks, such as during World War II. Most of these breeds have increased in numbers again through breeding over many generations, creating a stable population of healthy dogs.

There are two main factors to consider when assessing the genetic diversity and health of a particular breed: average inbreeding and the number of deleterious recessive genes. Within a small population, there is a tendency for average inbreeding coefficients to increase due to the fact that many dogs are related and share common ancestors. However, there is no specific level or percentage of inbreeding that results in poor health or vitality. The problems that arise as a result of inbreeding depression arise from the influence of harmful recessive genes. If many copies of a particular deleterious gene were present in the founding population of a breed, then there is a possibility that a disease or condition associated with that gene will be common in the breed. These conditions may include small litter size, increased neonatal mortality, increased incidence of genetic disease, or decreased immunity. If these problems are present in a breed, breeders should seriously consider increasing genetic diversity.

A high coefficient of inbreeding occurs during the creation of almost any dog ​​breed. As the population of a breed increases, the average relatedness of dogs decreases (over a certain number of generations) and the coefficient of inbreeding within the breed also decreases. The impact of high inbreeding coefficients when breeding a breed on its future health will depend on the number of harmful recessive genes that will manifest themselves in a homozygous state.

Some breeders condemn linebreeding and encourage outbreeding in an attempt to maintain the genetic diversity of their breed. But the reason for the loss of alleles in a population is not due to the breeding method (linebreeding or outbreeding). It occurs as a result of selection: the use of some descendants and the non-use of others. A decrease in genetic diversity in a population occurs when breeders narrow the range of dogs used for breeding to a few bloodlines.

Maintaining healthy lines by crossing dogs from different lines with each other and, if necessary, using linebreeding maintains the diversity of the breed's genetic pool.

If some breeders outbreed and linebreed on dogs they like, and other breeders inbred on other dogs they like, the genetic diversity of the breed will remain at a good level. Breeders' different ideas about what the breed ideal is and which sires should be used in their breeding program help maintain genetic diversity.

One of the main factors reducing the genetic diversity of breeds is popular buck syndrome. Excessive use of a popular dog beyond reasonable limits significantly shifts the genetic pool of the breed towards him and thereby reduces diversity. The number of any of its genes - good or bad - in the population increases. This “founder effect” can lead to breed diseases.

Another negative consequence of the effect of a popular male is a decrease in the genetic contribution to the breed of other, unrelated males, who are not in demand for breeding. Each year a certain, limited number of females are bred. If the same male is used many times, then there simply is not enough females left to mate with other quality males that can contribute to the genetic pool. Popular male syndrome has a serious impact not only on small breeds, but also on breeds with a fairly high population.

To ensure the health and genetic diversity of the breed, the following methods must be used:

Avoid popular male syndrome

Use a wide range of quality sires to increase the genetic pool

Monitor the health of the breed through regular research

Conduct genetic testing for breed diseases

Enter data about representatives of the breed into open registries containing information about the health of dogs, such as CHIC to track genetic diseases.

PAGE 1

Lecture 2

Genetic diversity

This diversity (or genetic variation) within a species;

This is the difference between populations within the same species

The level of genetic diversity determines the adaptive abilities of a population during environmental changes, and its viability in general.

population

The term (from Latin populus people, population) was introduced by the Danish geneticist Wilhelm Johannsen in 1903.

Currently, the concept population is used to denotea self-renewing group of individuals of a species, which occupies a certain space for a long time and is characterized by the exchange of genes between individuals, as a result of which a common genetic system is formed, different from the genetic system of another population of the same species Yes.

THOSE. the population should be characterized by panmixia - (from the Greek pan all, mixis mixing) free crossing of heterosexual individuals with different genotypes.

The set of genes that are present in individuals of one population (gene pool of a population) or all populations of a species (gene pool of a species) is called GENE POOL.

Primary mechanisms of genetic diversity

As is known, genetic diversity is determined by variation in the sequences of 4 complementary nucleotides in the nucleic acids that make up the genetic code. Each species carries a huge amount of genetic information: the DNA of bacteria contains about 1,000 genes, fungi - up to 10,000, higher plants - up to 400,000. Many flowering plants and higher taxa of animals have a huge number of genes. For example, human DNA contains more than 30 thousand genes. In total, living organisms on Earth contain 10 9 various genes.

Gene flow

The degree of isolation of populations of the same species depends on the distance between them and gene flow.Gene flow is the exchange of genes between individuals of the same population or between populations of the same species.. Gene flow within a population occurs as a result of random crossing between individuals whose genotypes differ in at least one gene.

Obviously, the rate of gene flow depends on the distance between sexual individuals.

Gene flow between populations depends on random migrations of individuals over long distances (for example, when birds carry seeds over long distances).

The flow of genes within a population is always greater than the flow of genes between populations of the same species. Populations that are far apart from each other are almost completely isolated.

The following indicators are used to describe genetic diversity:

• proportion of polymorphic genes;
• allele frequencies of polymorphic genes;
• average heterozygosity for polymorphic genes;
• genotype frequencies.

Allele frequencies of polymorphic genes

Individuals of one population usually differ in genotypes, then different alleles are represented in the gene pool of the population by different numbers of individuals (i.e., they have different frequencies in the population. For example, in a person, the frequency of the dominant allele for normal pigmentation of the skin, eyes and hair is 0.99 or 99%. In this case, the recessive allele of albinism (lack of pigmentation) occurs with a frequency of 0.01 or 1%.

In 1908, the English mathematician J. Hardy and the German physician W. Weinberg independently proposed a mathematical model for calculating the frequency of alleles and genotypes in a population.

Let us remember that heterozygotes Aa form 2 types of gametes:

gametes
	AA	Ahh
	aA	ahh

The offspring of a cross between heterozygous individuals will be both homozygous and heterozygous.

Now let's see what will happen in a population when individuals are crossed, if it is known that the frequency of occurrence of the allele “ A" makes p, and alleles "a" make q.

Gamete frequencies	p(A)	q(a)
p(A)	P 2 (AA)	pq Aa
q(a)	pq(aA)	q 2 (aa)

Since the sum of the frequencies of dominant and recessive alleles = 1, then

Allele frequencies can be calculated using the formula p + q =1

And the frequencies of genotypes according to p 2 + 2 pq + q 2 = (p + q ) 2 = 1

In the second generation, the proportion of gametes is “A”= p 2 + (2 pq)/2 = p (p + q) = p,

and the proportion of gametes “a” = q 2 + (2 pq)/2 = q (p + q) = q

Hardy-Weinberg Law:

The frequencies of dominant and recessive alleles in a population will remain constant from generation to generation under certain conditions.

1. panmictic Mendeleevian population (panmictic crossing of any individuals of different sexes is equally likely); (Mendelian inheritance of traits according to Mendel’s laws)

2. no new mutations

3. all genotypes are equally fertile, i.e. there is no natural selection

4. Complete isolation of the population (no exchange of genes with other populations).

Corollary of the Hardy-Weinberg law:

1. A significant proportion of the recessive alleles present in the population are in a heterozygous state. These heterozygous genotypes are a potential source of genetic variation in the population.

Many recessive alleles (which appear in the phenotype only in the homozygous state) are unfavorable for the phenotype. Since the frequency of homozygous phenotypes with recessive alleles is not high in the population, a small part of the recessive alleles is eliminated from the population in each generation.

2. The concentration of alleles and genotypes in a population can change under the influence of factors external to the population: gene recombination during sexual reproduction (combinatorial variability), mutations, population waves, non-random crossing, genetic drift, gene flow and natural selection of phenotypes.

Gene recombination

Main sources of education new genotypes gene recombination.

Sources of genetic recombination

1) independent divergence of homologous chromosomes in anaphase 1 of the meiotic division;

2) random combination of chromosomes (and gametes) during fertilization;

3) crossing over) exchange of sections of homologous chromosomes in prophase of the 1st division of meiosis

All these processes can lead to the formation of new genotypes and, as a consequence, to changes in genotype frequencies. But they do not lead to the formation of new alleles and, therefore, do not affect changes in allele frequencies in the population.

Occurrence of mutations

New alleles as a result of mutations rarely but constantly appear in nature, since there are many individuals of each species and many loci arise in the genotype of any organism.

The mutation process serves as a source of the appearance of new mutant alleles and rearrangements of genetic material. We remember that a single mutation is a rare event. The increase in their frequency in a population under the influence of mutation pressure occurs extremely slowly, even on an evolutionary scale. In addition, the vast majority of mutations that arise are eliminated from the population within a few generations due to random reasons.

For humans and other metazoans, it has been shown that mutations usually occur with a frequency of 1 in 100,000 up to 1 per 1,000,000 gametes.

Moreover, the process of mutation occurrence in natural conditions is continuous. Therefore, in natural populations of different organisms there are from several percent to tens of percent of individuals carrying mutations. If such individuals are crossed with other individuals, then new combinations of alleles arise as a result of genetic recombination.

New mutations somehow disrupt the existing genotype of the organism; many are lethal, semi-lethal or sterile. During sexual reproduction, a significant part of the mutations are transferred to a heterozygous state. This is the so-called genetic load of the population - its payment for the opportunity to maintain genetic diversity for the subsequent formation of new phenotypes, which may be more adapted to changed environmental conditions.

On average, a zygote has 3-5 harmful lethal mutations in the heterozygous state. In the presence of unfavorable alleles and their combinations, approximately zygotes do not participate in the transmission of genes to the next generation. It is estimated that in the human population, about 15% of conceived organisms die before birth, 3 at birth, 2 immediately after birth, 3 die before reaching puberty, 20 do not marry, 10% of marriages are childless.

Mutations that can lead to the death of the organism or its weakening in the homozygous state do not show their negative effect on the development of the organism in the heterozygous state and can even have a positive effect on the viability of individuals (for example, the sickle cell anemia mutation in the heterozygous state reduces susceptibility to malaria) .

We especially note that in different environmental conditions the same mutation can have different effects on the viability of the organism. French geneticist J. Tessier conducted an experiment with flies with reduced wings. He kept wingless flies along with winged ones in open boxes on the seashore and indoors. After two months, the number of wingless flies in the first box on the seashore increased from 2.5 to 67%, and in the second, wingless flies disappeared.

That. mutations are random and undirected changes in the gene pool, which are the source of genetic variability of the population and, existing in a heterozygous state, represent a potential reserve for natural selection.

Gene FLOW from other populations

Rather, the immigration of individuals into a new population often entails the appearance of new alleles in the gene pool of that population.

With a unidirectional flow, significant changes in the gene pool of the population can occur

At uniform flowgenes (mutual exchange of genes) there is an equalization of gene frequencies in both populations. This uniform flow of genes unites all populations into a single genetic system called a species.

Population fluctuations

Fluctuations in the number of individuals in populations are characteristic of all living organisms when the environment changes. In a simplified form: deterioration of conditions causes the death of some individuals, improvement is accompanied by an increase in the number of individuals.Such fluctuations in numbers are usually wave-like.For example, in many rodents, an increase in available food causes the population to grow to critical levels. As a result, the aggressiveness of rodents towards each other increases; in females, hormonal disorders occur, leading to the resorption of embryos and, as a consequence, to a drop in fertility.

It is obvious that when numbers fall, some of the alleles disappear from the population along with dying individuals. For the first time, the Russian geneticist S.S. drew attention to the genetic consequences of changes in the number of individuals. Chetverikov. He proposed to call periodic changes in population density "population waves" or "waves of life".

Genetic drift

In populations with a small number of mature individuals, random mating can quickly lead to an increase in the frequency of a rare allele or to its disappearance and, as a consequence, to a decrease in genetic diversity. This phenomenon was first discovered in 1931 by Russian geneticists Romashov and Dubinin. Regardless of them, the American geneticist S. Wright, who named him genetic drift . Wright's experiment: in test tubes with food, 2 females and 2 males of Drosophila heterozygous for gene A (frequency of both alleles = 0.5). After 16 generations, both alleles remained in some populations, in others only the “A” allele, and in others only the “a” allele. That. in populations there was a rapid loss of one of the alleles or a change in the frequency of one of the alleles.

Non-random crossing

The Hardy-Weinberg law is observed only with panmixia - equally probable crossing of individuals with different genotypes in the same population. In natural populations, panmixia is never complete. For example, in entomophilous plants, insects are more likely to visit larger or brighter flowers with more nectar or pollen.

Assortative crossing: partners of the same population select each other based on their phenotype. For example, in the populations of many beetles, large individuals mate only with large ones, and small ones with small ones.

Inbreeding inbreeding. Possible in the formation of strictly isolated family groups into which strangers are not allowed. The dominant male in such a group mates with all females, including his own daughters. This type of crossing leads to homozygosity of genotypes and a decrease in the genetic diversity of the population (see also hemophilia in the ruling dynasties of Europe and Russia).

Selective crossbreedingpreferential reproduction of individuals with certain characteristics (for example, more actively courting the female). For example, in populations of chickens, magpies, etc., from 10 to 40% of all males participate in reproduction.

In general, non-random crossing leads to a decrease in the genetic diversity of the population.

That. Natural populations of organisms are constantly influenced by many factors that determine their genetic diversity:

1. Mutations.

2. Population waves.

3. Non-random crossing.

4. Genetic drift.

5. Gene flow.

6. Natural selection of phenotypes

Genetic diversity in artificial populations (plant varieties, animal breeds, microorganism strains) is significantly influenced by purposeful human activity SELECTION.

A person selects traits that are not always necessary and useful for the existence of a species (population), but which are beneficial to humans (see, for example, meat and dairy breeds of cows, dwarf cows, Kenyan cows).

HORIZONTAL GENE TRANSFER

see also unusually interesting article

A. V. Markov

Horizontal gene transfer and evolution

http://warrax.net/94/10/gorizont.html

http://macroevolution.narod.ru/lgt2008/lgt2008.htm

Perhaps the most curious and not fully understood factor today, which can also influence genetic diversity, is the so-called horizontal gene transfer.

Today's data suggest that during evolution, gene transfers occurred both within and between kingdoms.

For example, E. coli has 4289 genes. Of these, 755 (i.e. 18%) were transferred.

• On average, in bacteria the share of obtained genes is 10-15%. According to the latest data, there may be more.
• The greatest number of transfers is typical for free-living bacteria with wide ecological ranges.
• The smallest number of transfers was found in pathogenic bacteria living in narrow ecological niches.
• Most often, genes associated with metabolism, transport pathways, and signal transduction are involved in horizontal transfer.
• Horizontal gene transfer is realized through various channels of genetic communication - the processes of conjugation, transduction, transformation, etc.
• Closely related microbes exchange genes much more often than phylogenetically distant ones.

So, let's summarize. Genetic diversity depends on:

the proportion of polymorphic genes genes that have several alleles (human blood groups A, B, O);

allele frequencies for polymorphic genes;

average heterozygosity for polymorphic genes;

genotype frequencies;

migration processes;

intensity of the mutation process;

actions of natural selection;

duration of evolution;

Population size (in small ones there are many random processes);

Gene linkage (with natural selection, not only the selected allele A, but also the neutral genes linked to it will be preserved)

horizontal gene transfer;

human participation (for example, during breeding work).