The founders of the modern (synthetic) theory of evolution THE FOUNDERS OF MODERN
(SYNTHETIC) THEORY OF EVOLUTION
Fundamentals of the doctrine of
natural selection were
laid down by Charles Darwin in his
works on the theory of evolution
(Darwinism). Concept of
natural selection
has expanded significantly and
deepened thanks to
development of genetics, works
I.I. Shmalhausen and S.S.
Chetverikova.

Modern ideas about natural selection

The concept of “natural selection”

Stabilizing selection

Driving selection

Destabilizing selection

Destabilizing selection

Disruptive form of selection

Disruptive selection

Other forms of natural selection SEXUAL SELECTION

intraspecific and interspecific selection

Other forms of natural selection

THE CREATIVE ROLE OF NATURAL SELECTION IS MANIFESTED IN THE fact that, ACTING FOR MILLIONS AND BILLIONS OF YEARS, IT TOGETHER WITH OTHER FACTORS

Comparison of natural and artificial selection fill out the table

Task: match

Answers

Homework

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“Presentation for the lesson “Forms of natural selection””

Natural selection- This is the selective survival and reproduction of the most adapted organisms. (C. Darwin)

Natural selection - this is a process as a result of which the most adapted individuals of each species predominantly survive and leave offspring and the less adapted ones die

Forms

natural selection

Disruptive

Stabilizing

Moving

Selection form

Terms of action

Stabilizing

Result

Moving

Disruptive

The theory of stabilizing selection was developed by the outstanding evolutionary biologist Academician Ivan Ivanovich Shmalgauzen (1884-1963).

Ivan Ivanovich Shmalhausen

• In slightly variable (constant) environmental conditions, the number of individuals with an average reaction rate increases. From generation to generation, extreme forms are cut off, and organisms with a certain reaction norm are fixed (preservation of the average phenotypic norm)

GINKGO

It was described by Charles Darwin. The very name “driving” suggests that such selection determines the direction of evolution.

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.”

(C. Darwin)

Polymorphism

Sexual dimorphism

Secondary sexual characteristics

Identify examples of which form of natural selection are given below:

1. Stability (constancy) of flower sizes and shapes in insect-pollinated plants.

2. Changes in pests under the influence of pesticides.

3. Coelacanth fish.

4. Most hares in the population have medium-sized ears.

6. Insects that ended up on an oceanic island became wingless.

8. Elephants arrived on the Mediterranean island at the end of the Tertiary period. In conditions of limited resources of island forests, individuals with small sizes had an advantage; elephants of normal size died. This is how dwarf elephants arose.

9. Existence of tree ferns in Africa in the Semiliki River valley

Homework

Comparative characteristics of natural and artificial selection.

Criteria

Natural selection

Source material for selection

Artificial selection

Selective factor

Favorable changes

Fitness

Driving selection The driving form contributes to a shift in the average value of a trait or property and leads to a new average norm instead of the old one, which no longer corresponds to new conditions. The driving form contributes to a shift in the average value of a characteristic or property and leads to a new average norm instead of the old one, which no longer corresponds to new conditions. Operates when environmental conditions change. Operates when environmental conditions change.

Thus, the leading role in the spread of new characteristics within a species when environmental conditions change belongs to the driving form of natural selection. Changes in symptoms can occur both in the direction of its intensification, greater severity, and in the direction of weakening until complete disappearance.

The role of selection in nature is not limited to the elimination of individual traits that reduce viability or competitiveness. The role of selection in nature is not limited to the elimination of individual traits that reduce viability or competitiveness. In reality, in nature, selection preserves not individual traits, but entire phenotypes, i.e. the whole complex of characteristics, and therefore certain combinations of genes inherent in a given organism. In reality, in nature, selection preserves not individual traits, but entire phenotypes, i.e. the whole complex of characteristics, and therefore certain combinations of genes inherent in a given organism.

Stabilizing selection Operates under constant environmental conditions. Operates in constant environmental conditions. Aimed at maintaining a previously established average trait or property: the size of the body or its individual parts in animals, the size and shape of a flower in plants, etc. Aimed at maintaining a previously established average trait or property: the size of the body or its individual parts in animals, the size and shape of a flower in plants, etc.

A stabilizing type of selection preserves the fitness of the species by eliminating sharp deviations in the expression of a trait from the average norm. A stabilizing type of selection preserves the fitness of the species by eliminating sharp deviations in the expression of a trait from the average norm. Genes that cause deviations from the norm are eliminated from the gene pool of the species. Genes that cause deviations from the norm are eliminated from the gene pool of the species. The stabilizing form of natural selection protects the existing genotype from the destructive effects of the mutation process. The stabilizing form of natural selection protects the existing genotype from the destructive effects of the mutation process.

Sexual selection is the competition between males for the opportunity to reproduce. Sexual selection is the competition between males for the opportunity to reproduce. This form of selection should be considered a special case of intraspecific natural selection. This form of selection should be considered a special case of intraspecific natural selection.

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Presentation - Natural selection is the main driving force of evolution

Text of this presentation

Natural selection is the main driving force of evolution.

GOALS
Develop concepts about various forms of natural selection. To formulate in students the ability to compare different forms of natural selection with each other and correctly identify them by their essential characteristics. To consolidate knowledge about natural selection - as the main and guiding driving force of the evolutionary process.

LESSON PLAN
The concept of "natural selection". Forms of natural selection. The creative role of natural selection. Sexual selection as a stabilizing form of natural selection. Comparison of natural and artificial selection.

EXPLAIN THE TERMS
Struggle for existence. Intraspecific struggle for existence. Interspecies struggle for existence. Combating unfavorable environmental conditions.

Intraspecific
Interspecific
Competition for water and food sources
Competition for nesting sites in birds
Displacement of one species by another from its habitat
Relationship between predator and prey
Struggle for existence

- These are complex and diverse relationships between individuals within species, between species and environmental conditions.
Struggle for existence
Intraspecific struggle occurs between individuals of the same species. This is the toughest and sharpest of all types. Competition between predators for prey, competition for territory, for a female, for living space, for breeding sites. Interspecific struggle leads to the evolution of both interacting species and to the development of mutual adaptations in them. Strengthens and aggravates intraspecific struggle. This is the unilateral use of one species by another. In the fight against unfavorable environmental conditions, the winners are the most viable individuals (with effective metabolism and physiological processes). These are plants and animals of the deserts and the far north.

Find relationships between concepts and pictures
Intraspecific struggle, interspecific struggle, struggle with unfavorable environmental conditions.
A)
B)
IN)
G)
D)
E)
AND)

GIVE ANSWERS TO QUESTIONS
1. What is the meaning of the struggle for existence?
- in the formation of fitness in organisms.
2. What is the result of the struggle for existence?
- natural selection.
3. What do you think natural selection is?
Natural selection -
survival of the fittest organisms.

GIVE ANSWERS TO QUESTIONS
4. How do adapted individuals arise?
- as a result of the action of the struggle for existence and natural selection.
5. Which variability is more important?
- hereditary variability.
The basis for the success of evolution is the diversity of organisms.

This is the selective survival and reproduction of the most adapted organisms (C. Darwin)
NATURAL SELECTION
Charles Robert Darwin (1809-1882) - English naturalist and traveler.
a process as a result of which the most fit individuals of each species preferentially survive and leave offspring and the least fit ones die

3. Selection factor
Natural environment with its own conditions

1.Necessary prerequisite
Hereditary variability
2.Character
Directional (always directed towards greater adaptability to the environment)

6. Consequence
Increasing the diversity of forms of organisms; consistent complication of organization in the course of progressive evolution; extinction of less adapted species
4.Genetic essence
Non-random preservation of certain genotypes in a population and their selective participation in the transmission of genes to the next generation
5.Result
Transformation of the population gene pool, formation of adaptations
CHARACTERISTICS OF NATURAL SELECTION

Natural selection is capable of purposefully selecting from generation to generation individuals that are more adapted to environmental conditions. By selecting useful traits, natural selection creates new species.
THE CREATIVE ROLE OF NATURAL SELECTION

NATURAL SELECTION
Reason: struggle for existence. Material: hereditary variability Efficiency: the more different mutations in a population (the higher the heterozygosity of the population), the greater the efficiency of natural selection, the faster evolution proceeds.

MECHANISM OF EVOLUTION (according to the theory of Charles Darwin)
Evolution is the process of historical development of living nature based on variability, heredity and natural selection.

Hereditary variability (mutations, combinative variability)
Heterogeneity of the population (the appearance of individuals with a variety of characteristics)
The struggle for existence (in its various manifestations)
“Defeat” of the least adapted individuals with unfavorable characteristics
“Victory” of the fittest individuals with important favorable characteristics
Selective elimination
They have no chance of procreation
Elimination from reproduction
Unfavorable traits are not passed on to offspring
Survival and preferential participation in reproduction
Favorable traits are passed on to descendants
NATURAL SELECTION

FORMS OF NATURAL SELECTION

DRIVING SELECTION
A
B
IN
G
A-D – successive changes in the reaction rate under the pressure of the driving force of natural selection
Selection pressure

DRIVING SELECTION
Leads to the destruction of individuals with the old norm of reaction and the formation of a population of individuals with new characteristics. It takes place in slowly changing environmental conditions. The resulting hereditary changes are beneficial.

Industrial melanism is variability caused by intensive industrial development and environmental deterioration.
Industrial melanism in the birch moth butterfly
The butterflies living on the trunks of birch trees were light in color. Among them, dark-colored forms appeared from time to time and were destroyed by birds. Due to the development of industry and air pollution, the trunks of birch trees have acquired a grayish tint. As a result, light-colored butterflies were destroyed by birds, while dark-colored ones were preserved. After some time, all butterflies in the population became dark-colored.

DRIVING SELECTION
Increasing horse body size
Phylogenetic series of the horse
Development of resistance to pesticides
Transforms species under changing environmental conditions. Ensures the widespread distribution of life, its penetration into all possible ecological niches. Under stable conditions of existence, natural selection does not cease, but continues to act in the form of stabilizing selection.

STABILIZING SELECTION
There is a narrowing of the reaction norm.
Initial variability of traits.
Selection pressure
Selection pressure

In slightly variable (constant) environmental conditions, the number of individuals with an average reaction rate increases. From generation to generation, extreme forms are cut off, and organisms with a certain reaction norm are fixed (preservation of the average phenotypic norm)
STABILIZING SELECTION

Hatteria
STABILIZING SELECTION
Preserves individuals with the norm of reaction established under given conditions and eliminates all deviations from it. Operates in environmental conditions that do not change for a long time.
Relic species

GINKGO (Ginkgo biloba), the only surviving species of the vast order Ginkgoidae, which flourished during the Mesozoic era. The only modern representative is G. biloba (G. biloba) - a tree 30-40 m high, up to 1 m thick, with a spreading crown; dioecious. Found in few areas of East Asia. The plant's name means "silver apricot" in Japanese.
STABILIZING SELECTION
Relic species

The flowers of snapdragon plants are pollinated by bumblebees. The size of the flowers corresponds to the body size of bumblebees. All plants that have flowers that are too large or too small are not pollinated and do not form seeds, that is, they are eliminated by stabilizing selection.
STABILIZING SELECTION
Snapdragon.

COMPARISON OF SELECTION FORMS
STABILIZING MOVING
1. Constancy of the external environment 1. Changes in environmental conditions
2. Neutralization of mutations by selecting combinations in which their harmful effects are neutralized 2. Opening up the stock of variability
3.Improving the genotype with a constant phenotype. 3. Selection of neutralizing mutations and their combinations
4. Formation of a mobilization reserve of hereditary variability 4. Formation of new genotypes and phenotypes

STABILIZING MOVING
By sweeping away deviations from the norm, it actively forms genetic mechanisms that ensure the stable development of organisms and the formation of optimal phenotypes based on various genotypes. It ensures the stable functioning of organisms in a wide range of fluctuations in external conditions familiar to the species. Plays a decisive role in the adaptation of living organisms to changing external conditions over time. Ensures the wide distribution of life, its penetration into all possible ecological niches. Under stable conditions of existence, natural selection continues to act in the form of stabilizing selection.
COMPARISON OF SELECTION FORMS

There is a gap in the reaction norm (individuals with an average value are displaced)
Selection pressure

The timing of flowering and seed ripening in the meadow rattle extends throughout almost the entire summer, with most of the plants blooming and bearing fruit in mid-summer. In hay meadows, those plants that have time to flower and produce seeds before mowing, and those that produce seeds at the end of summer, after mowing, benefit. As a result, two races of rattle are formed - early and late flowering.
DISRUPTIVE SELECTION (disruptive)
A type of natural selection in a population of animals or plants that leads to the emergence of two or more new forms from one original one.

For example, in the absence of food necessary for the growing juvenile perch, i.e., fry of other fish, only “dwarfs” (individuals with sharply slow growth, which can feed on planktonic crustaceans for a long time) and “giants” (individuals capable of already by the end of the first year of life they eat perch fry of their own generation). In such a situation in a reservoir for a number of years, as a result of D. o. Hereditary races of “giants” and “dwarfs” will be formed.
Sometimes environmental conditions change sharply, in such a way that extreme forms gain advantage. The number of extreme forms is rapidly increasing, which, with the participation of isolation, can lead to a transformation of the species. This selection is directed against intermediate forms.
DISRUPTIVE SELECTION (disruptive)

DISRUPTIVE SELECTION (disruptive)
The case of the predominant survival of “red” forms of the two-spotted ladybug in the winter season and “black” forms of the two-spotted ladybug in the summer season has been well studied.
This form of selection occurs when two or more genetically different forms have an advantage under different conditions, such as different seasons of the year.

NATURAL SELECTION
OPERATES FROM OUTSIDE STRENGTHENS ADAPTABILITY
ACTS FROM INSIDE IN TWO OR MORE DIRECTIONS
ONLY ACTS IN ONE DIRECTION
STABILIZING
MOVING
TEARING
TWO OR MORE NEW SIGNIFICANCE STANDARDS ARE FORMED
THE NORM OF THE CHARACTER DOES NOT CHANGE, BUT THE NUMBER OF INDIVIDUALS INCREASES
THE NORM OF A CHARACTER CHANGES

a form of natural selection in some animal species based on competition of one sex for mating with individuals of the other sex.
Polymorphism
Secondary sexual characteristics are a set of features or characteristics that distinguish one sex from another (with the exception of the gonads, which are primary sexual characteristics).
SEXUAL SELECTION
Sexual dimorphism
“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.” (C. Darwin)

POLYMORPHISM
Polymorphism is the existence within one species of several clearly morphologically different forms.
Polymorphism in dioecious animals is the presence of individuals of different appearance within the same sex.

POLYMORPHISM

POLYMORPHISM
Seasonal polymorphism is a type of ecological polymorphism. The appearance of the insect depends on the season.
In the population of moth butterflies, the generations that appear in the spring are distinguished by the reddish-red color of their wings with a characteristic arrangement of dark spots. At the same time, the summer generation consists of individuals with brown wings. This phenomenon is due to the fact that in spring, at lower temperatures, the butterfly’s body produces less dark pigment, which is responsible for the color of the wings.

POLYMORPHISM
In social insects, sexual polymorphism is observed, associated with the division of functions of different individuals in a family or colony (for example, the queen and workers in bees).

1. The starting material for natural selection is A) the struggle for existence B) mutational variability C) changes in the habitat of organisms D) the adaptability of organisms to the environment 2. Charles Darwin’s evolutionary theory is based on the doctrine of A) divergence B) natural selection C ) degeneration D) artificial selection 3. Selection, as a result of which individuals with an average manifestation of a trait are preserved, and individuals with deviations from the norm are discarded, is called A) driving B) methodical C) spontaneous D) stabilizing 4. The creative nature of natural selection is manifested in evolution in A) increased competition between species B) weakened competition between populations C) increased competition between individuals of the same species D) the emergence of new species 5. The effectiveness of natural selection decreases with A) increased intraspecific struggle B) changes in the reaction norm C) weakening of the mutation process D) strengthening the mutation process
Generalization test

6. What does the strengthening of the mutation process in a natural population lead to? A) increasing the efficiency of natural selection B) increasing the intensity of the cycle of substances C) increasing the number of individuals D) improving self-regulation 7. The action of natural selection leads to A) mutational variability B) preservation of traits useful for humans C) random crossing D) the emergence of new species 8. The result of evolution is A) hereditary variability B) struggle for existence C) diversity of species D) aromorphosis 9. Thanks to what form of selection have lobe-finned fish been preserved in nature? A) methodical B) driving C) stabilizing D) breaking 10. The main result of evolution is A) the adaptation of organisms to the environment B) fluctuations in population numbers C) a decrease in the number of populations of a species D) the struggle for existence between individuals of the same species
Generalization test

Answers to the generalization test
1 2 3 4 5 6 7 8 9 10
B B G G V A G V V A

Source material for selection
Selective factor
The path of favorable changes
The Path of Unfavorable Change
Nature of action
Selection result
Selection forms

Indicators Artificial selection Natural selection
Source material for selection Individual characteristics of an organism Individual characteristics of an organism
Selecting factor Human Environmental conditions
Path of favorable changes Selected, become productive Remain, accumulate, passed on by inheritance
The path of unfavorable changes Selected, rejected, destroyed Destroyed in the struggle for existence
Nature of action Creative - directed accumulation of traits for the benefit of man Creative - selection of adapted traits for the benefit of an individual, population, species, leading to the emergence of new forms
Result of selection New varieties of plants, breeds of animals, strains of microorganisms New species
Forms of selection Mass, individual, unconscious, methodical Driving, stabilizing, disruptive, sexual

HOMEWORK
§3.4, pp. 136 – 139 textbook for students. education institutions prof. education “General Biology” V.M. Konstantinov. § 47, pp. 166 – 169 textbook “General Biology” D.K. Belyaeva. Fill out the table “Comparative characteristics of artificial and natural selection”

Thank you for your attention!

General biology: a textbook for students. education institutions of secondary prof. education / V.M. Konstantinov, A.G. Rezanov, E.O. Fadeeva; edited by V.M. Konstantinova.- M.: Publishing center "Academy", 2010. General biology: Textbook. For 10-11 grades. general education institutions/ D.K. Belyaev, P.M. Borodin, N.N. Vorontsov and others; Ed. D.K. Belyaeva, G.M. Dymshitsa. – M.: Education, 2005. – 304 p. Lerner G.I. Biology lessons. General biology. 10th, 11th grades. Tests, questions, tasks: Study guide. – M.: Eksmo, 2005. – 352 p. I.F. Ishkina Biology. Lesson plans. 11th grade / Ed. D.K. Belyaeva, A.O. Ruvinsky. – Volgograd, 2002. – 120 p. Petunin O.V. Biology lessons in 11th grade. Detailed planning - Yaroslavl: Development Academy, Academy Holding, 2003. - 304 p.
INFORMATION SOURCES

INFORMATION SOURCES
1.H. Darwin http://images.francetop.net/uploads/charles%20darwin_22044.jpg 2. Hatteria http://www.infoniac.ru/upload/medialibrary/4d1/4d1bcf404cd0d2b318284ea3631c96c1.jpg 3. Snapdragon http://img0. liveinternet.ru/images/attach/c/5/87/832/87832648_9.jpg 4. Birch moth http://zagony.ru/uploads/posts/2011-08/thumbs/1313568467_015.jpg http://www. warrenphotographic.co.uk/photography/cats/11321.jpg 5. Ginkgo http://permian.files.wordpress.com/2007/02/ginkgo-tuileries.jpg 6. Polymorphism in bees http://i-pchela. ru/images/stories/family/sem.jpg 7. Ant http://www.pchelandiya.net/uploads/posts/2011-11/1322639656_x_eabc9ab21.jpg 8. Polymorphism of the dove-gray iris http://hnu.docdat.com/ pars_docs/refs/174/173704/img4.jpg 9. Seasonal polymorphism of the variable wing http://www.pesticidy.ru/ps-content/dictionary/pictures/165_content_page.jpg 10. Forms of natural selection http://ucheba-legko .ru/lections/viewlection/biologiya/11_klass/evolyutsiya/mehanizmyi_evolyutsionnogo_protsessa/lec_formyi_estestvennogo_otbora 11.Okun http://mediasubs.ru/group/uploads/se/sekretyi-ryibnoj-lovli/image2/jEyLThjZj.jpg

INFORMATION SOURCES
12. “Black form” of a two-spot ladybug http://www.wallpage.ru/imgbig/wallpapers_68505.jpg 13. “Red form” of a two-spot ladybug http://img10.proshkolu.ru/content/media/pic/std /4000000/3054000/3053496-c3f1628c64b89ffa.jpg

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