Natural selection. The driving force of evolution: what forms of natural selection exist

Mechanism of natural selection

In progress natural selection mutations are fixed that increase the fitness of organisms. Natural selection is often called a "self-evident" mechanism because it follows from such simple facts, How:

1. Organisms produce more offspring than can survive;
2. There is heritable variation in the population of these organisms;
3. Organisms with different genetic traits have different survival rates and ability to reproduce.

The central concept of the concept of natural selection is the fitness of organisms. Fitness is defined as an organism's ability to survive and reproduce, which determines the size of its genetic contribution to the next generation. However, the main thing in determining fitness is not the total number of descendants, but the number of descendants with a given genotype (relative fitness). For example, if the offspring of a successful and rapidly reproducing organism are weak and do not reproduce well, then the genetic contribution and therefore the fitness of that organism will be low.

Natural selection for traits that can vary over some range of values ​​(such as the size of an organism) can be divided into three types:

1. Directional selection- changes in the average value of a trait over time, for example an increase in body size;
2. Disruptive selection- selection for extreme values ​​of a trait and against average values, for example, large and small body sizes;
3. Stabilizing selection- selection against extreme values ​​of a trait, which leads to a decrease in the dispersion of the trait and a decrease in diversity.

A special case of natural selection is sexual selection, the substrate of which is any trait that increases the success of mating by increasing the attractiveness of the individual to potential partners. Traits that have evolved through sexual selection are especially noticeable in the males of some animal species. Characteristics such as large horns and bright coloring, on the one hand, can attract predators and reduce the survival rate of males, and on the other hand, this is balanced by the reproductive success of males with similar pronounced characteristics.

Selection can operate at different levels of organization, such as genes, cells, individual organisms, groups of organisms, and species. Moreover, selection can simultaneously act on different levels. Selection at levels above the individual, for example group selection, can lead to cooperation (see Evolution#Cooperation).

Forms of natural selection

There are different classifications of selection forms. A classification based on the nature of the influence of forms of selection on the variability of a trait in a population is widely used.

Driving selection

Driving selection- a form of natural selection that operates when directed changing environmental conditions. Described by Darwin and Wallace. In this case, individuals with traits that deviate in a certain direction from the average value receive advantages. In this case, other variations of the trait (its deviations in the opposite direction from the average value) are subject to negative selection. As a result, a shift occurs in the population from generation to generation average size sign in a certain direction. In this case, the pressure of driving selection must correspond to the adaptive capabilities of the population and the rate of mutational changes (otherwise, environmental pressure can lead to extinction).

An example of the action of driving selection is “industrial melanism” in insects. “Industrial melanism” is a sharp increase in the proportion of melanistic (dark-colored) individuals in those populations of insects (for example, butterflies) that live in industrial areas. Due to industrial impact, the tree trunks darkened significantly, and light-colored lichens also died, which is why light-colored butterflies became better visible to birds, and dark-colored ones became less visible. In the 20th century, in some areas, the proportion of dark-colored butterflies in some well-studied moth populations in England reached 95%, while for the first time the dark-colored butterfly ( morpha carbonaria) was captured in 1848.

Driving selection occurs when there is a change environment or adaptation to new conditions when the range expands. It preserves hereditary changes in a certain direction, moving the reaction rate accordingly. For example, during the development of soil as a habitat, various unrelated groups of animals developed limbs that turned into burrowing limbs.

Stabilizing selection

Stabilizing selection- a form of natural selection in which its action is directed against individuals with extreme deviations from the average norm, in favor of individuals with an average expression of the trait. The concept of stabilizing selection was introduced into science and analyzed by I. I. Shmalgauzen.

Many examples of the action of stabilizing selection in nature have been described. For example, at first glance it seems that greatest contribution Individuals with maximum fertility should be added to the gene pool of the next generation. However, observations of natural populations of birds and mammals show that this is not the case. The more chicks or cubs in the nest, the more difficult it is to feed them, the smaller and weaker each of them is. As a result, individuals with average fertility are the most fit.

Selection toward the mean has been found for a variety of traits. In mammals, very low-weight and very high-weight newborns are more likely to die at birth or in the first weeks of life than average-weight newborns. Taking into account the size of the wings of sparrows that died after a storm in the 50s near Leningrad showed that most of them had wings that were too small or too large. And in this case, the average individuals turned out to be the most adapted.

Disruptive selection

Disruptive selection- a form of natural selection in which conditions favor two or more extreme variants (directions) of variability, but do not favor the intermediate, average state of a trait. As a result, several new forms may appear from one original one. Darwin described the action of disruptive selection, believing that it underlies divergence, although he could not provide evidence for its existence in nature. Disruptive selection contributes to the emergence and maintenance of population polymorphism, and in some cases can cause speciation.

One of the possible situations in nature in which disruptive selection comes into play is when a polymorphic population occupies a heterogeneous habitat. At the same time, different forms adapt to different ecological niches or sub-niches.

An example of disruptive selection is the formation of two races in the greater rattle in hay meadows. Under normal conditions, the flowering and seed ripening periods of this plant cover the entire summer. But in hay meadows, seeds are produced mainly by those plants that manage to bloom and ripen either before the mowing period, or bloom at the end of summer, after mowing. As a result, two races of rattle are formed - early and late flowering.

Disruptive selection was carried out artificially in experiments with Drosophila. The selection was carried out according to the number of bristles; only individuals with a small and large number of bristles were retained. As a result, from about the 30th generation, the two lines diverged very much, despite the fact that the flies continued to interbreed with each other, exchanging genes. In a number of other experiments (with plants), intensive crossing prevented the effective action of disruptive selection.

Sexual selection

Sexual selection- This is natural selection for reproductive success. The survival of organisms is an important, but not the only component of natural selection. To others essential component is attractive to individuals of the opposite sex. Darwin called this phenomenon sexual selection. “This form of selection is determined not by the struggle for existence in the relations of organic beings among themselves or with external conditions, but by the competition between individuals of one sex, usually males, for the possession of individuals of the other sex.” Traits that reduce the viability of their hosts can emerge and spread if the advantages they provide for reproductive success are significantly greater than their disadvantages for survival. Two main hypotheses about the mechanisms of sexual selection have been proposed. According to the “good genes” hypothesis, the female “reasons” as follows: “If this male, despite his bright plumage and long tail, somehow managed not to die in the clutches of a predator and survive to puberty, then, therefore, he has good genes.” genes that allowed him to do this. This means that he should be chosen as a father for his children: he will pass on his good genes to them.” By choosing colorful males, females are choosing good genes for their offspring. According to the “attractive sons” hypothesis, the logic of female choice is somewhat different. If brightly colored males, for whatever reason, are attractive to females, then it is worth choosing a brightly colored father for his future sons, because his sons will inherit the brightly colored genes and will be attractive to females in the next generation. Thus, a positive feedback arises, which leads to the fact that from generation to generation the brightness of the plumage of males becomes more and more intensified. The process continues to grow until it reaches the limit of viability. In the choice of males, females are no more and no less logical than in all their other behavior. When an animal feels thirsty, it does not reason that it should drink water in order to restore the water-salt balance in the body - it goes to a watering hole because it feels thirsty. In the same way, females, when choosing bright males, follow their instincts - they like bright tails. All those to whom instinct suggested a different behavior, all of them did not leave offspring. Thus, we were discussing not the logic of females, but the logic of the struggle for existence and natural selection - a blind and automatic process that, acting constantly from generation to generation, has formed all the amazing diversity of shapes, colors and instincts that we observe in the world of living nature .

Positive and negative selection

There are two forms of natural selection: Positive And Cut-off (negative) selection.

Positive selection increases the number of individuals in a population that have useful traits that increase the viability of the species as a whole.

Eliminating selection eliminates from a population the vast majority of individuals that carry traits that sharply reduce viability under given environmental conditions. Using selection selection, highly deleterious alleles are removed from the population. Also, individuals with chromosomal rearrangements and a set of chromosomes that sharply disrupt the normal functioning of the genetic apparatus can be subjected to cutting selection.

The role of natural selection in evolution

In the example of the worker ant we have an insect extremely different from its parents, yet absolutely sterile and, therefore, unable to transmit from generation to generation acquired modifications of structure or instincts. You can set good question- How is it possible to reconcile this case with the theory of natural selection?

- Origin of Species (1859)

Darwin assumed that selection could apply not only to an individual organism, but also to a family. He also said that perhaps, to one degree or another, this could explain people's behavior. He was right, but it was only with the advent of genetics that it became possible to provide a more expanded view of the concept. The first sketch of the “theory of kin selection” was made by the English biologist William Hamilton in 1963, who was the first to propose considering natural selection not only at the level of an individual or an entire family, but also at the gene level.

see also

Notes

1. , With. 43-47
2. , p. 251-252
3. Orr H.A. Fitness and its role in evolutionary genetics // Nat Rev Genet. - 2009. - Vol. 10(8). - P. 531-539.
4. Haldane J The theory of natural selection today // Nature. - 1959. - Vol. 183. - P. 710-713.
5. Lande R, Arnold SJ The measurement of selection on correlated characters // Evolution. - 1983. - Vol. 37. - P. 1210–26). - DOI:10.2307/2408842
6. , Chapter 14
7. Andersson M, Simmons L Sexual selection and mate choice // Trends Ecol Evol. - 2001. - Vol. 21(6). - P. 296-302.
8. Kokko H, Brooks R, McNamara J, Houston A The sexual selection continuum // Proc Biol Sci. - 2002. - Vol. 269. - P. 1331-1340.
9. Hunt J, Brooks R, Jennions MD, Smith MJ, Bentsen CL, Bussière LF High-quality male field crickets invest heavily in sexual display but die young // Nature. - 2004. - Vol. 432. - P. 1024-1027.
10. Okasha, S. Evolution and the Levels of Selection. - Oxford University Press, 2007. - 263 p. - ISBN 0-19-926797-9
11. Mayr E The objects of selection // Philos. Trans. R. Soc. Lond., B, Biol. Sci. - 1998. - T. 353. - P. 307–14.
12. Maynard Smith J The units of selection // Novartis Found. Symp. - 1998. - T. 213. - P. 211–217.
13. Gould SJ, Lloyd EA Individuality and adaptation across levels of selection: how shall we name and generalize the unit of Darwinism? // Proc. Natl. Acad. Sci. U.S.A.. - 1999. - T. 96. - No. 21. - P. 11904–11909.
14. Ethology. Ru: Moral animal, part 2
15. Kin selection. The evolution of cooperation and altruism.

Links

• “Forms of natural selection” - article with good famous examples: color of butterflies, human resistance to malaria, etc.
• On the Origin of Species by Charles Darwin – Chapter 4, Natural Selection

Natural selection increases the chances of survival and continuation of the entire species; it is on the same level as mutations, migrations and transformations in genes. The basic mechanism of evolution operates flawlessly, but on condition that no one interferes with its work.

What is natural selection?

The meaning of this term was given by the English scientist Charles Darwin. He established that natural selection is a process that determines the survival and reproduction of only individuals adapted to environmental conditions. According to Darwin's theory, random hereditary changes play the most important role in evolution.

• recombination of genotypes;
• mutations and their combinations.

Natural selection in humans

In times of underdeveloped medicine and other sciences, only a person with a strong immune system and a stable healthy body survived. They did not know how to care for premature newborn babies, they did not use antibiotics in treatment, they did not perform operations, and they had to cope with their illnesses on their own. Natural selection among people selected the strongest representatives of humanity for further reproduction.

IN civilized world It is not customary to have numerous offspring and in most families there are no more than two children, who, thanks to modern conditions life and medicine, may well live to a ripe old age. Previously, families had 12 or more children, and no more than four survived under favorable conditions. Natural selection in humans has led to the fact that the hardened, exceptionally healthy and strong people. Thanks to their gene pool, humanity still lives on earth.

Reasons for natural selection

All life on earth developed gradually, from the simplest organisms to the most complex. Representatives of certain forms of life that were unable to adapt to the environment did not survive and did not reproduce; their genes were not passed on to subsequent generations. The role of natural selection in evolution led to the emergence of the ability to cellular level adapt to the environment and quickly respond to its changes. The causes of natural selection are influenced by a number of simple factors:

1. Natural selection works when more offspring are produced than can survive.
2. There is hereditary variability in the genes of an organism.
3. Genetic differences dictate survival and reproductive ability in different environments.

Signs of natural selection

The evolution of any living organism is the creativity of nature itself and is not her whim, but a necessity. Operating in different environmental conditions, it is not difficult to guess what traits natural selection preserves; all of them are aimed at the evolution of the species, increasing its resistance to external influences:

1. The selecting factor plays an important role. If in artificial selection a person chooses which characteristics of a species to preserve and which not (for example, when breeding a new breed of dog), then with natural selection the strongest wins in the struggle for its existence.
2. Material for selection are hereditary changes, the signs of which can help in adaptation to new living conditions or for specific purposes.
3. The result is another stage of natural selection, as a result of which new species with characteristics that are beneficial in certain environmental conditions were formed.
4. Speed ​​of action - Mother Nature is in no hurry, she thinks about every step, and therefore natural selection is characterized by a low rate of change, while artificial selection is characterized by a fast rate.

What is the result of natural selection?

All organisms have their own degree of adaptability and it is impossible to say with certainty how a particular species will behave in unfamiliar environmental conditions. The struggle for survival and hereditary variability are the essence of natural selection. There are many examples of plants and animals that were brought from other continents, and which have taken root better in new living conditions. The result of natural selection is a whole set of acquired changes.

• adaptation - adaptation to new conditions;
• variety of forms of organisms - arise from a common ancestor;
• evolutionary progress – increasing complexity of species.

How does natural selection differ from artificial selection?

It is safe to say that almost everything that is consumed by humans has sooner or later been subjected to artificial selection. The only fundamental difference is that when conducting “his” selection, a person pursues his own benefit. Thanks to selection, he obtained selected products and developed new breeds of animals. Natural selection is not oriented toward the benefit of humanity; it pursues only the interests of this particular organism.

Natural and artificial selection equally influence the lives of all people. They fight for the life of a premature baby, just like for the life of a healthy one, but at the same time, natural selection kills drunkards frozen on the streets, fatal diseases take lives ordinary people, mentally unstable people commit suicide, natural disasters collapse to the ground.

Types of natural selection

Why are only certain representatives of species able to survive in different environmental conditions? Forms of natural selection are not written rules of nature:

1. Driving selection occurs when environmental conditions change and species have to adapt; it preserves the genetic heritage in certain directions.
2. Stabilizing selection is aimed at individuals with deviations from the average statistical norm in favor of average individuals of the same species.
3. Disruptive selection is when individuals with extreme indicators survive, and not with average ones. As a result of such selection, two new species can be formed at once. More often found in plants.
4. Sexual selection is based on reproduction, when the key role is played not by the ability to survive, but by attractiveness. Females, without thinking about the reasons for their behavior, choose beautiful, bright males.

Why is man able to weaken the influence of natural selection?

Progress in medicine has stepped far forward. People who were supposed to die survive, develop, and have their own children. By passing on their genetics to them, they give birth to a weak race. Natural selection and the struggle for existence collide hourly. Nature comes up with more and more sophisticated ways to control people, and humans try to keep up with it, thereby preventing natural selection. Human humanitarianism leads to weak-looking people.

Natural selection is a process originally defined by Charles Darwin as leading to the survival and preferential reproduction of individuals more adapted to given environmental conditions and possessing useful hereditary traits. In accordance with Darwin's theory and the modern synthetic theory of evolution, the main material for natural selection is random hereditary changes - recombination of genotypes, mutations and their combinations.

In the absence of the sexual process, natural selection leads to an increase in the proportion of a given genotype in the next generation. However, natural selection is “blind” in the sense that it “evaluates” phenotypes rather than genotypes, and the preferential transmission of the genes of an individual with useful traits to the next generation occurs regardless of whether these traits are heritable.

There are different classifications of selection forms. A classification based on the nature of the influence of forms of selection on the variability of a trait in a population is widely used.

Driving selection- a form of natural selection that operates under directed changes in environmental conditions. Described by Darwin and Wallace. In this case, individuals with traits that deviate in a certain direction from the average value receive advantages. In this case, other variations of the trait (its deviations in the opposite direction from the average value) are subject to negative selection. As a result, in a population from generation to generation there is a shift in the average value of the trait in a certain direction. In this case, the pressure of driving selection must correspond to the adaptive capabilities of the population and the rate of mutational changes (otherwise, environmental pressure can lead to extinction).

An example of the action of driving selection is “industrial melanism” in insects. “Industrial melanism” is a sharp increase in the proportion of melanistic (dark-colored) individuals in those populations of insects (for example, butterflies) that live in industrial areas. Due to industrial impact, the tree trunks darkened significantly, and light-colored lichens also died, which is why light-colored butterflies became better visible to birds, and dark-colored ones became less visible. In the 20th century, the proportion of dark-colored butterflies in some well-studied moth populations in England reached 95% in some areas, while the first dark-colored butterfly (morfa carbonaria) was captured in 1848.

Driving selection occurs when the environment changes or adapts to new conditions when the range expands. It preserves hereditary changes in a certain direction, moving the reaction rate accordingly. For example, during the development of soil as a habitat, various unrelated groups of animals developed limbs that turned into burrowing limbs.

Stabilizing selection- a form of natural selection in which its action is directed against individuals with extreme deviations from the average norm, in favor of individuals with an average expression of the trait. The concept of stabilizing selection was introduced into science and analyzed by I.I. Schmalhausen.

Many examples of the action of stabilizing selection in nature have been described. For example, at first glance it seems that the greatest contribution to the gene pool of the next generation should be made by individuals with maximum fertility. However, observations of natural populations of birds and mammals show that this is not the case. The more chicks or cubs in the nest, the more difficult it is to feed them, the smaller and weaker each of them is. As a result, individuals with average fertility are the most fit.

Selection toward the mean has been found for a variety of traits. In mammals, very low-weight and very high-weight newborns are more likely to die at birth or in the first weeks of life than average-weight newborns. Taking into account the size of the wings of sparrows that died after a storm in the 50s near Leningrad showed that most of them had wings that were too small or too large. And in this case, the average individuals turned out to be the most adapted.

Disruptive selection- a form of natural selection in which conditions favor two or more extreme variants (directions) of variability, but do not favor the intermediate, average state of a trait. As a result, several new forms may appear from one original one. Darwin described the action of disruptive selection, believing that it underlies divergence, although he could not provide evidence of its existence in nature. Disruptive selection contributes to the emergence and maintenance of population polymorphism, and in some cases can cause speciation.

One of the possible situations in nature in which disruptive selection comes into play is when a polymorphic population occupies a heterogeneous habitat. At the same time, different forms adapt to different ecological niches or subniches.

An example of disruptive selection is the formation of two races in the greater rattle in hay meadows. Under normal conditions, the flowering and seed ripening periods of this plant cover the entire summer. But in hay meadows, seeds are produced mainly by those plants that manage to bloom and ripen either before the mowing period, or bloom at the end of summer, after mowing. As a result, two races of rattle are formed - early and late flowering.

Disruptive selection was carried out artificially in experiments with Drosophila. The selection was carried out according to the number of bristles; only individuals with a small and large number of bristles were retained. As a result, from about the 30th generation, the two lines diverged very much, despite the fact that the flies continued to interbreed with each other, exchanging genes. In a number of other experiments (with plants), intensive crossing prevented the effective action of disruptive selection.

Sexual selection- This is natural selection for reproductive success. The survival of organisms is an important, but not the only component of natural selection. Another important component is attractiveness to individuals of the opposite sex. Darwin called this phenomenon sexual selection. “This form of selection is determined not by the struggle for existence in the relations of organic beings among themselves or with external conditions, but by the competition between individuals of one sex, usually males, for the possession of individuals of the other sex.” Traits that reduce the viability of their hosts can emerge and spread if the advantages they provide for reproductive success are significantly greater than their disadvantages for survival. Two main hypotheses about the mechanisms of sexual selection have been proposed. According to the “good genes” hypothesis, the female “reasons” as follows: “If this male, despite his bright plumage and long tail, somehow managed not to die in the clutches of a predator and survive to puberty, then, therefore, he has good genes.” genes that allowed him to do this. This means that he should be chosen as a father for his children: he will pass on his good genes to them.” By choosing colorful males, females are choosing good genes for their offspring. According to the “attractive sons” hypothesis, the logic of female choice is somewhat different. If brightly colored males, for whatever reason, are attractive to females, then it is worth choosing a brightly colored father for his future sons, because his sons will inherit the brightly colored genes and will be attractive to females in the next generation. Thus, there is a positive Feedback, which leads to the fact that from generation to generation the brightness of the plumage of males increases more and more. The process continues to grow until it reaches the limit of viability. In the choice of males, females are no more and no less logical than in all their other behavior. When an animal feels thirsty, it does not reason that it should drink water in order to restore the water-salt balance in the body - it goes to a watering hole because it feels thirsty. In the same way, females, when choosing bright males, follow their instincts - they like bright tails. All those to whom instinct suggested a different behavior, all of them did not leave offspring. Thus, we were discussing not the logic of females, but the logic of the struggle for existence and natural selection - a blind and automatic process that, acting constantly from generation to generation, has formed all the amazing diversity of shapes, colors and instincts that we observe in the world of living nature .

One of the main mechanisms of evolution, along with mutations, migration processes and gene transformations, is natural selection. Types of natural selection involve changes in the genotype that increase the organism's chances of survival and procreation. Evolution is often seen as a consequence of this process, which may arise from differences in species survival, fertility, development rates, mating success, or any other aspect of life.

Natural balance

Gene frequencies remain constant from generation to generation, provided that there are no disturbing factors that upset the natural balance. These include mutations, migration (or gene flow), random genetic drift, and natural selection. A mutation is a spontaneous change in the frequency of genes in a population characterized by a low rate of development. In this case, an individual moves from one population to another and then changes. Random is a change that is transmitted from one generation to the next in a completely random manner.

All of these factors change gene frequencies without regard to increasing or decreasing the organism's likelihood of surviving and reproducing in its natural environment. All of them are random processes. And natural selection, types of natural selection, are moderate disorganizing consequences of these processes, since they increase the frequency of beneficial mutations over many generations and eliminate harmful components.

What is natural selection?

Natural selection promotes the preservation of those groups of organisms that are better adapted to the physical and biological conditions of their habitat. He
can act on any heritable phenotypic trait and, through selective pressure, can influence any aspect of the environment, including sexual selection and competition with members of the same or other species.

However, this does not mean that this process is always directed and effective in adaptive evolution. Natural selection, types of natural selection in general, often results in the elimination of less fit options.

Variation exists within an entire population of organisms. This occurs in part because random mutations occur in the genome of one organism, and its offspring can inherit such mutations. Throughout life, genomes interact with the environment. Consequently, the population evolves.

The concept of natural selection

Natural selection is one of the cornerstones modern biology. It acts on a phenotype whose genetic basis provides a reproductive advantage for greater prevalence in the population. Over time, this process can lead to the emergence of new species. In other words, this is an important (though not the only) evolutionary process within a population.
The concept itself was formulated and published in 1858 by Charles Darwin and Alfredo Russell Wallace in a joint presentation of papers regarding

The term has been described as analogous i.e. it is the process by which animals and plants with certain traits are considered desirable for breeding and reproduction. The concept of "natural selection" was originally developed in the absence of a theory of heredity. At the time Darwin wrote his works, science had yet to develop the combination of traditional Darwinian evolution with subsequent discoveries in the field of classical and molecular genetics is called the modern evolutionary synthesis. 3 types of natural selection remain the main explanation for adaptive evolution.

How does natural selection work?

Natural selection is the mechanism by which an animal organism adapts and evolves. At their core, individual organisms that are best adapted to their environment survive and reproduce most successfully, producing fertile offspring. After numerous breeding cycles, such species are dominant. Thus, nature filters out poorly adapted individuals for the benefit of the entire population.

It is a relatively simple mechanism that causes members of a given population to change over time. In fact, it can be broken down into five main stages: variation, inheritance, selection, time and adaptation.

Darwin on natural selection

According to Darwin's teachings, natural selection consists of four components:

1. Variations. Organisms within a population exhibit individual differences in appearance and behavior. These changes may include body size, hair color, facial markings, vocal characteristics, or the number of offspring produced. On the other hand, some personality traits are not associated with differences between individuals, such as the number of eyes in vertebrates.
2. Inheritance. Some traits are passed on sequentially from parents to offspring. Such traits are heritable, while others are strongly influenced by environmental conditions and are weakly inherited.
3. High populations. The majority of animals annually produce offspring in much greater quantities than is necessary for an equal distribution of resources between them. This leads to interspecific competition and premature mortality.
4. Differential survival and reproduction. All types of natural selection in populations leave behind those animals that know how to fight for local resources.

Natural selection: types of natural selection

Darwin's theory of evolution radically changed the direction of future scientific thought. At its center is natural selection, a process that occurs over successive generations and is defined as the differential reproduction of genotypes. Any change in the environment (for example, a change in the color of a tree trunk) can lead to adaptation at the local level. There are the following types of natural selection (Table No. 1):

Stabilizing selection

Often, the frequency of DNA mutations is statistically higher in some species than in others. This type of natural selection tends to eliminate any extremes in the phenotypes of the most environmentally fit individuals in a population. Due to this, diversity within one species decreases. However, this does not mean that all individuals are exactly the same.

Stabilizing natural selection and its types can be briefly described as averaging or stabilization, in which the population becomes more homogeneous. Polygenic traits are primarily affected. This means that the phenotype is controlled by multiple genes and there is a wide range of possible outcomes. Over time, some of the genes are turned off or masked by others, depending on favorable adaptation.

Many human characteristics are the result of such selection. A person's birth weight is not only a polygenic trait, it is also controlled by environmental factors. Newborns with an average birth weight are more likely to survive than those who are too small or too large.

Directed natural selection

This phenomenon is usually observed in conditions that have changed over time, for example weather, climate or food supply can lead to directional selection. Human participation can also speed up this process. Hunters most often kill large specimens for meat or other large ornamental or useful parts. Consequently, the population will tend to skew towards smaller individuals.

The more predators kill and eat slow individuals in the population, the more there will be a bias towards luckier and faster members of the population. Types of natural selection (table with examples No. 1) can be more clearly demonstrated using examples from living nature.

Charles Darwin studied directional selection while he was in the Galapagos Islands. The beak length of native finches has varied over time due to available food sources. In the absence of insects, finches survived with large and long beaks, which helped them eat seeds. Over time, insects became more numerous, and with the help of directed selection, bird beaks gradually acquired smaller sizes.

Features of diversification (disruptive) selection

Disruptive selection is a type of natural selection that opposes the averaging of species characteristics within a population. This process is the rarest, if we describe the types of natural selection briefly. Diversification selection can lead to the speciation of two or more various forms in places of sudden environmental changes. Like directed selection, this process can also be slowed down due to the destructive influence of human factors and environmental pollution.

One of the best-studied examples of disruptive selection is the case of butterflies in London. In rural areas, almost all individuals were light in color. However, these same butterflies were very dark in color in industrial areas. There were also specimens with medium color intensity. This is due to the fact that dark butterflies have learned to survive and escape predators in industrial areas in urban environments. Light-colored moths in industrial areas were easily detected and eaten by predators. The opposite picture was observed in rural areas. Butterflies of medium color intensity were easily visible in both locations and therefore very few remained.

Thus, the meaning of disruptive selection is to move the phenotype towards an extreme that is necessary for the survival of the species.

Natural selection and evolution

The basic idea of ​​the theory of evolution is that all species diversity gradually evolved from simple life forms that appeared more than three billion years ago (for comparison, the age of the Earth is approximately 4.5 billion years). Types of natural selection, with examples from the first bacteria to the first modern humans, played a significant role in this evolutionary development.

Organisms that have been poorly adapted to their environment are less likely to survive and produce offspring. This means their genes are less likely to be passed on to the next generation. The path to genetic diversity must not be lost, nor must the ability at the cellular level to respond to changing environmental conditions.

Did life arise by chance or by design? What role do fear and sexual arousal play in life? How did order emerge from the primordial chaos?

The topics of the article go beyond psychology. The more clearly they reflect individual mental patterns.

Natural selection can be likened to a pattern that permeates all living things - both on a dense and on a mental level. I myself am familiar with the theory, like most, at the level of rumors and fragmentary knowledge from school curriculum. But nothing more is required. To independently observe the influence of ancient trends in the present time, it is enough to understand the basic principle of natural selection. I will describe it in my own words.

First, a couple of paragraphs about a common incorrect view of the phenomenon.

Natural selection is often presented as a principle based on which nature prudently destroys unadapted, weak organisms, inflicting various blows of fate on them, so that in the end the strongest - the owners of “favorable characteristics” - survive. Nature from this perspective appears intelligent, as if it whimsically evaluates all living things and deliberately selects the best for itself.

But there are no selfish intentions behind this selection. Natural selection occurs naturally. The term was promoted by Charles Darwin. He contrasted it with artificial selection - the deliberate selection of animals (and plants) to produce offspring with desirable qualities: high-yielding cows, hardy horses, well-fed pigs, fluffy cats.

Nature did not set any goals for itself. We can say that nature, as an independent phenomenon, does not exist at all - it is simply a collection of living and nonliving “matter” in the space of life. Matter moves spontaneously. The tendencies of this movement reveal the transient and the stable.

Survival

Natural selection can be reduced to a simple formulation: what survives lives. Whatever it is: a human form, a rock, the Holy Spirit. And if you carefully follow this tenacious creature, you will notice that a significant part of its properties, as if deliberately, serves precisely survival.

For example, as they say, plants reach for the sun to get the most solar energy for photosynthesis. The wording makes it sound as if plants have a will and personal intentions, because they are methodically “active” for the benefit of life.

In fact, the plants do not reach for the sun at all, and do not try to get anything. It just happens. Without any purpose - they have no nervous system, no conscious will. It’s just that the plants, which also randomly stretched in the other direction, did not survive. Therefore, only these remained, striving for warmth and light.

How did it happen that the plants began to stretch in one direction or another? The answer is spontaneous mutations, unpredictable changes in the genome that are passed on to descendants.

Each type of life has undergone many changes over time that we are not even aware of. Because only those organisms that, through mutations, acquired vitality have survived to this day. Randomly. This is natural selection.

And this happens with everything in nature. The tenacious lives not because it plans to do so, but because it naturally continues in time due to its accidental adaptability. The tenacious survived. The fragile was destroyed. This is all selection in its utmost naturalness.

Imagine that time is a straining sieve for chaos. Everything falls into it: plants, animals, planets, galaxies. And almost everything goes into oblivion. But individual rare forms, as if clinging to time, remain because they randomly acquired the qualities of stability. In living organisms we call these qualities instincts.

Ants have inhabited the planet for 130 million years, as if they were deliberately trying to do so. But such reasoning is of one’s own humanity. We believe in our will and project it onto all living things. We see how organisms adapt and survive as if they had intelligence and conscious intentions. We attribute human motives to the behavior of insects similar to ours. And the real reason, again, is random formations. This time in the nervous system.

Imagine the abstract ancestors of all living things. Due to mutations, they developed a variety of unexpected tendencies - to avoid the cold, reach for warmth, run away from the big and agile one, or move towards it. Do you get it? Creatures that randomly avoided dangers naturally survived and managed to pass on their genes to their descendants. All other less durable modifications died out, so we don’t see them.

As a result, the modern ant is the owner of refined automatisms of survival and reproduction - those same instincts.

Today's reality is stable forms of chaos, which, having withstood the face of time, have survived to this day. Mountains, deserts, air - nothing threatens them on earth, so they are preserved. It is not individual living individuals who are so durable in nature, but biological species. The existence of a lone ant is under threat every second. The ant species has thrived for millions of years.

From this perspective, the only main instinct can be traced - survival. Reproduction is one of the methods of survival of a species.

Reproduction is not required for the survival of an individual. Therefore, in our time, individualists are in no hurry to have children.

Still herd instincts, or if you like - social programs personality, it makes sense to recognize and take into account. Everything we feel is aimed at serving not so much our unique person, but the entire human species as a whole. Therefore, we have developed not only “” self-care, but also the need to support others.

Do you want to reach agreement with yourself? Respect your ancient instincts, find healthy compromises with them.

Reproduction

Next step. Look within yourself. Have you ever thought about the nature of orgasm, or do you take it for granted? They say, what is there to think about? It’s nice - and there’s nothing to philosophize about. Where did this “nice” come from? It's not hard to figure out.

Individuals who did not care about sex did not reproduce and did not pass on their genes. But the ancestors of our libido (sexual arousal) randomly received a mutation that made sex attractive.

At first, the sensation could be subtle, far from the brightness of a modern orgasm. But still, it encouraged us to continue to reproduce and pass on our newborn sexual instinct to future generations.

Individuals in whom this mutation was more pronounced reproduced even faster. Over time, a new instinct was added to the excitement - the pangs of abstinence. Those who suffered from abstinence began to reproduce with zealous persistence.

As a result, sexuality has become one of the key motives governing life. All modern culture, no matter how sublime and multifaceted, can be reduced to serving basic instincts - survival and reproduction.

The theory of natural selection allows us to notice that this is such a spontaneous creativity of nature. For example, fear is the stronghold of the most painfully acute experiences that drove our ancestors away from death; and orgasm is a filtered hodgepodge of all the random joy that accompanied reproduction.

It is known that male orgasm is a matter of minutes. If desired. In many animals, close to their ancient nature, copulation lasts seconds - no more is required to continue the species.

According to the logic of natural selection, a man and a woman should experience the greatest joy specifically from the process of fertilization. But nature failed to coordinate orgasms. Therefore, the process is simplified as much as possible for the active side, which is represented by men. The female orgasm does not proceed so unhindered, because it is less important for the continuation of the species.

And here we need to understand how much modern “superstructures” interfere with the basic “programs” of the psyche. There would be no demographic crises if people had learned to fool their ancient essence with interrupted coitus and masturbation.

Don't take this as criticism of society. Just thinking out loud.

Homosapiens programs

Now let's look into human psychology. It is infinitely diverse. So many different feelings: interest, surprise, sadness, anger, disgust, guilt, indescribable mixes of unique moods...

Now, let’s assume that natural selection goes through not only organisms, but also feelings. Those that contribute to the survival of the species remain.

Imagine that your body is a spacesuit for feelings. Fear is the oldest feeling, one of the most tenacious. Fear, again, led our ancestors away from danger, and through the lives it saved, continued its journey in descendants.

A kind of survival marathon, where participants one by one disappear from the stream of time. But the ancient relay baton has been preserved and even grown in size.

Modern man has been trained to fear more than his predecessors. Fear does not go away from generation to generation, but grows and crystallizes, because it contributes to the survival and development of the species of frightened creatures “Homo sapiens”.

Is the creation of the world accidental?

Does a creation require some kind of initial design if it spontaneously obeys an extremely logical scheme from the “first nail”? The fragile collapses, the strong remains. This is the natural trajectory of matter in time. In this vein, survival human species resembles the formation of stalactites at the bottom of a cave. It just happens. Naturally.

Order is a form of stable edges of chaos. Think about it.

If you look at life through the prism of natural selection, you will notice that all human culture arose as spontaneously as the pattern of coffee grounds at the bottom of a cup. And this is no less surprising than the world created according to the Creator’s plan. Especially when you remember the highest meanings of art and science.

Try, for example, to realize that the device from which you are now reading this text is one of the random turns of chaos. Just like everyone else. You yourself are a spontaneous deformation of matter, a spontaneous side effect of the big bang.

The present moment is sacred because right now you can feel the current form of the most ancient process of spontaneous “building” of the world. This ancient randomness was centered at the core of your being as you experience life as yourself.

The theory of natural selection is materialistic - it seems to confirm that creation was the result of chance and did not require divine intervention. And yet, natural selection does not deny the intentional creation of the world, but rather refines tendencies that do not require direct control of higher powers. If you have a flexible mind, theory can be squeezed even into an esoteric worldview.

Charles Darwin himself did not consider himself a materialist, but was an adherent of agnosticism - a worldview that asserts the impossibility of comprehending the absolute foundations of reality. Simply put, an agnostic is a person who does not know. Sincerely.

And personally, I share this approach.

The human psyche deserves a separate discussion. Our mind, if you look closely, also serves the basic survival instinct. In such a curly way that the whole procedure really looks like some kind of mockery of higher powers.

The mind recreates a miniature of reality within itself, accepts it as objective - and reacts instinctively to these hand-made holograms. .

Also, I personally don’t understand where the sense of “I”, self-awareness and personal will come from in this picture. Another random mutation?

Instincts flow as naturally as clouds form in the sky. It just happens. The ant functions in the same way due to inherent internal tendencies. This happens to us too. . Spontaneously. But why does the viewer need to worry about all this? Another involuntary survival program? Or is it just machinations? higher power? There is something irrationally incomprehensible about all this.

Was the world created by chance, or according to a deliberate plan?

Elon Musk, the founder of the Paypal payment system, confidently stated in an interview that our world is virtual, that is, an analogue of the matrix from the film of the same name. And he brought up an original argument. I will retell it in my own words.

Considering the rapid development virtual reality, where multiplayer games with “photorealistic” graphics are already widely available, one can reasonably assume that the artificial world will one day become indistinguishable from the objective one. Billions of users will be able to run it on their personal computers and consoles.

Think about it: billions of imitations, indistinguishable from real life... From this perspective, the probability that our reality is objective is one in billions.

In reality, of course, it is impossible to compile statistics. But the hypothesis sounds reasonable and may reflect reality.

For myself, I realized that the more sincere the doubts about the Divine, the more sincere is the faith, no matter how small it may become due to these doubts. Therefore, here too I urge you not to take anyone’s word for it, but to honestly doubt and research.