Evolution of the organic world. Biological species, its population structure. Theories of evolution of the organic world the concept of evolution The theory of evolution of the historical development of the organic world of the earth
Evolution (from Latin evolutio - deployment), in a broad sense - a synonym for development; processes of change (primarily irreversible) occurring in animate and inanimate nature, as well as in social systems. Evolution can lead to complication, differentiation, an increase in the level of organization of the system (progress) or, conversely, to a decrease in this level (regression). In a narrow sense, the concept of evolution includes only gradual quantitative changes, opposing it to development as a qualitative shift, that is, revolution. In real development processes, revolution and evolution (in the narrow sense) are equally necessary components and form a contradictory unity.
Evolution in the broad sense of the word refers to the gradual change of complex systems over time. They talk about the evolution of stars and galaxies, landscapes and biocenoses, languages and social systems.
Biological evolution is a hereditary change in the properties and characteristics of living organisms over a number of generations. In the course of biological evolution, an agreement is achieved and constantly maintained between the properties of living organisms and the conditions of the environment in which they live. Since conditions are constantly changing, including as a result of the vital activity of the organisms themselves, and only those individuals that are best adapted to life in changed environmental conditions survive and reproduce, the properties and signs of living beings are constantly changing. The conditions of life on Earth are infinitely diverse, so the adaptation of organisms to life in these different conditions has given rise in the course of evolution to a fantastic variety of life forms.
Driving forces of evolution, their relationship.
1. The teachings of Ch. Darwin about the driving forces of evolution. Driving forces of evolution: hereditary variability, struggle for existence, natural selection.
2. Hereditary variability. The reason for hereditary changes is a change in genes and chromosomes, a recombination (combination) of parental traits in offspring. Beneficial, harmful and neutral hereditary changes. Random, undirected nature of hereditary changes. The role of hereditary variation in evolution: the supply of material for the action of natural selection.
4. Forms of struggle for existence:
Fight against unfavorable conditions of inanimate nature (abiotic factors). Influence on any organism of unfavorable conditions: excess or lack of moisture, light, high or low air temperature. Example: death or oppression of individuals of a light-loving plant in low light conditions;
Intraspecific struggle for existence - the relationship between individuals of the same species. The greatest intensity of intraspecific struggle due to the similarity of needs in individuals of the same species (the need for similar food, lighting, soil, etc.).
5. Natural selection - the process of survival of individuals with hereditary changes that are useful in given environmental conditions and their subsequent reproduction. Selection is a consequence of the struggle for existence, the main factor of evolution, preserving individuals mainly with hereditary changes that are useful in certain environmental conditions. The selecting factor is environmental conditions: high or low air temperature; excess or lack of moisture, light, food.
6. The mechanism of action of natural selection:
The appearance of hereditary changes in individuals (beneficial, harmful, neutral);
Preservation as a result of the struggle for existence, natural selection, predominantly individuals with hereditary changes that are useful in given environmental conditions;
Reproduction of individuals with useful changes, increase in their number;
Preferential survival of individuals with changes corresponding to the environment among the offspring, their reproduction and transmission of useful changes to a part of the offspring;
Distribution of hereditary changes useful in given environmental conditions.
7. The relationship of the driving forces of evolution. Heterogeneity of individuals of a species due to hereditary variability, supplying material for the action of the struggle for existence and for natural selection. Exacerbation of relationships between individuals as a result of the struggle for existence. Preservation of individuals predominantly with beneficial hereditary changes by natural selection as a consequence of the struggle for existence.
It is important to note that Charles Darwin laid the foundations of the scientific theory of evolution. As the dominant evolutionary doctrine, Darwinism existed from 1859 to 1900, i.e. before the rediscovery of G. Mendel's laws. Until the end of the 20s of the current century, genetic data were opposed to evolutionary theory, hereditary variability (mutational, combinative) was considered as the main factor in evolution, natural selection was assigned a secondary role. Thus, already in the initial period of its formation, genetics was used to create new concepts of evolution. In itself, this fact is significant: it testified to the close connection of genetics with evolutionary theory, but the time for their unification was yet to come. Various kinds of criticism of Darwinism were widespread until the emergence of STE.
An exceptional role in the development evolutionary doctrine played by population genetics, which studies microevolutionary processes in natural populations. It was founded by outstanding domestic scientists S.S. Chetverikov and N.V. Timofeev-Resovsky.
The unification of Darwinism and genetics, which began in the 1920s, contributed to the expansion and deepening of the synthesis of Darwinism with other sciences. The 1930s and 1940s are considered to be the period of formation of the synthetic theory of evolution.
AT Western countries renewed Darwinism, or the synthetic theory of evolution, gained wide acceptance among scientists as early as the 1940s, although there have always been and still are some major researchers who take anti-Darwinian positions.
Modern science has very many facts proving the existence of the evolutionary process. These are data from biochemistry, genetics, embryology, anatomy, taxonomy, biogeography, paleontology and many other disciplines. The main evidence to date is:
taxonomy data reflecting the course of evolutionary transformations;
embryological evidence obtained in the study of the development of chordate embryos, confirming the validity of the law of germinal similarity of K. Baer. In addition, it was shown that in the course of its individual development, an organism passes through stages that reflect the phylogeny of a given species. Based on these data, the biogenetic law was formulated (F. Muller, E. Haeckel);
cellular structure;
comparative anatomy data;
data obtained during selection work;
evidence of the existence of natural selection in nature (melanization of insects);
universality of the genetic code;
the unity of the organization of genetic material and the implementation of genetic information;
the universality of the energy accumulator in a living cell - ATP;
genetic evidence. Phylogenetically close species have similarities in the structure of genes;
similarity in the structure of proteins of organisms belonging to close taxonomic groups;
experimental evidence. Modeling of evolutionary processes on living organisms (models).
Modern ideas about the factors of evolution are the result of the development of Darwinism, genetics and ecology. Charles Darwin in his classic work "The Origin of Species" solved the problem of the main driving forces (factors) of the evolutionary process. He singled out the following factors: heredity, variability and natural selection. In addition, Charles Darwin pointed out the important role of limiting the free interbreeding of individuals due to their isolation from each other, which arose in the process of evolutionary divergence of species.
In the modern view, the factors of the evolutionary process are hereditary variability, natural selection, genetic drift, isolation, migration of individuals, etc. All organisms form natural groups with similar anatomical features of the individuals included in them. Large groups are successively divided into smaller ones, the representatives of which have an increasing number of common features. It has long been known that organisms of a similar anatomical structure are similar in their embryonic development. However, sometimes even significantly different species, such as turtles and birds, are almost indistinguishable in the early stages of individual development. The embryology and anatomy of organisms are so closely correlated with each other that taxonomists (specialists in the field of classification) use the data of both these sciences equally in developing schemes for the distribution of species into orders and families. Such a correlation is not surprising, since the anatomical structure is the end result of embryonic development.
The direction of evolution of each systematic group is determined by the relationship between the features of the environment in which the evolution of a given taxon takes place and its genetic organization, which has developed in the course of its previous evolution.
Divergence. Most often in the course of evolution, we observe divergence or divergence of characters in species descended from a common ancestor. Divergence begins at the population level. It is due to differences in the environmental conditions in which the daughter species live and to which the daughter species adapt differently under the influence of natural selection. Genetic drift also plays a certain role in divergence. Divergence causes an increase in the number of species and continues at the level of supraspecific taxa. It is divergent evolution that accounts for the amazing diversity of living beings.
A striking example of divergence is the change in the limbs of mammals in the course of their adaptation to different environmental conditions.
Convergence (convergence of characters) is observed when unrelated taxa adapt to the same conditions. Convergence is spoken of in those cases when an external similarity is found in the structure and functioning of an organ that has completely different origins in the compared groups of living organisms. For example, the wing of a dragonfly and a bat have common features in structure and function, but are formed during embryonic development from completely different cellular elements and are controlled by different groups of genes. Such bodies are called similar. They are outwardly similar, but different in origin, they do not have a phylogenetic commonality. The similarity in eye structure between mammals and cephalopods is another example of convergence. They arose independently in the course of evolution and are formed in ontogeny from different rudiments.
General and private fixtures. Questions about the possible paths of the evolutionary process were developed by A. N. Severtsov. One of the main such ways, according to Severtsov, is aromorphosis (arogenesis), or the emergence in the course of evolution of adaptations that significantly increase the level of organization of living organisms and open up completely new evolutionary possibilities for them. Such adaptations were, for example, the emergence of photosynthesis, sexual reproduction, multicellularity, pulmonary respiration in the ancestors of amphibians, amniotic membranes in the ancestors of reptiles, warm-bloodedness in the ancestors of birds and mammals, etc. Aromorphoses are a natural result of evolutionary processes. They open up opportunities for species to explore new, previously inaccessible habitats.
Aromorphoses do not occur instantly; when they appear, they are practically indistinguishable from ordinary adaptations. Only with their evolutionary "polishing" by natural selection, coordination with numerous signs of the organism and wide distribution in many species, do they become aromorphoses. For example, the appearance of pulmonary respiration in the ancient inhabitants of fresh water did not radically change their lifestyle, level of organization, etc. However, as a result of this adaptation, it became possible to develop land - a vast habitat. This opportunity was actively used in subsequent evolution, many thousands of species of amphibians, reptiles, birds and mammals appeared, filling various habitat niches. Therefore, the acquisition of lungs by vertebrates is a major aromorphosis, which led to an increase in the level of organization of many species.
There are also smaller aromorphoses. There were several of them in the evolution of mammals: the appearance of a coat, live birth, feeding of young with milk, the acquisition of a constant body temperature, the progressive development of the brain, etc. The high level of organization of mammals, achieved due to the listed aromorphoses, allowed them to master new habitats.
In addition to such a major transformation as aromorphosis, in the course of the evolution of individual groups, a large number of small adaptations to certain environmental conditions arise. A. N. Severtsov called such adaptations idioadaptation.
Idioadaptation is the adaptation of organisms to the environment without a fundamental restructuring of the biological organization. An example of idioadaptation is the diversity of forms in insectivorous mammals, different species of which, having a common initial level of organization, were able to acquire properties that allowed them to occupy different habitats in nature.
The paths of evolution of the organic world either combine with each other or replace each other, and aromorphoses occur much less often than idioadaptation. But it is aromorphoses that determine new stages in the development of the organic world. Having arisen by aromorphosis, new, higher in organization groups of organisms occupy a different habitat. Further, evolution follows the path of idioadaptation, and sometimes degeneration, which provide organisms with the development of a new habitat for them.
2. CHANGES IN BASIC INDUSTRIES
With the beginning of the transition to a post-industrial society, the share of industry in world GDP and employment of the economically active population decreases. industry still remains the most important branch of material production. Large investments are directed to industrial production, large expenses for research and development work are associated with it. Manufactured goods retain unconditional primacy in world trade. Industry continues to have a great impact not only on the economy, but also on other aspects of public life. And the territorial structure of industry to the greatest extent determines the territorial structure of the entire world economy, forming, as it were, its framework. Therefore, it is sometimes not without reason continue to be called the engine of economic development.
Big shifts are taking place in the sectoral structure of world industry. At the mesostructure level, they are expressed primarily in a change in the proportion between the extractive and manufacturing industries. Throughout the second half of the twentieth century. there was a steady downward trend in the share of extractive industries in total industrial production; now it is about 1/10. But the changes also affected the internal proportions in the mining and manufacturing industries.
The extractive industry is a whole complex of industries and sub-sectors, which includes not only mining, but also the logging industry. It also includes marine fishing, water supply, hunting and fishing facilities. Approximately 3/4 of the total output of this industry falls on its main sub-sector - the mining industry. In turn, in the structure of the mining industry, 3/5 of the products (by value) are provided by the oil and gas industry, and the rest, in approximately equal shares, by coal and ore mining.
The manufacturing industry is structurally a much more complex complex, including more than 300 different industries and sub-sectors, which are usually divided into four blocks: 1) production of structural materials and chemical products; 2) mechanical engineering and metalworking; 3) light industry; 4) food industry. In the structure of manufacturing industries, heavy and light industries are also distinguished: if in the 60s the ratio between them was 60:40, then in the mid-90s it was already 70:30. The first place in the structure of the world manufacturing industry is occupied by mechanical engineering (40% of all products), the second place is occupied by the chemical industry (more than 15%). This is followed by food (14%), light industry (9%), metallurgy (7%) and other industries. The ratio between them changes somewhat with time, but in general remains relatively stable. On the other hand, the shifts taking place in the structure of each of these industries are usually more noticeable. First of all, this applies to mechanical engineering, as the most diversified branch of industrial production.
The fastest growing branch of world mechanical engineering has been and remains the electronic and electrical industry, whose share in all manufacturing products has already grown to 1/10. The general engineering industry as a whole is characterized by moderate growth, and changes are also taking place in its structure: the production of agricultural, textile machinery and equipment is decreasing, and the production of road transport machines is increasing, and especially robots, office equipment, etc. The share of transport engineering in The structure of the manufacturing industry as a whole remains relatively stable, but this also hides internal differences: the share of shipbuilding and rolling stock is declining, but the share of the automotive industry is generally maintained.
Along with shifts in the sectoral structure of world industry, there are changes in its territorial proportions. Usually these changes are considered at different hierarchical levels, ranging from the comparison of North and South to individual countries.
Exercise
The relic radiation discovered in the 1970s, that is, the microwave background radiation, began to be considered an experimental confirmation of the model: ...?
Initial stages of biological evolution
The appearance of the primitive cell meant the end of the prebiological evolution of the living and the beginning of the biological evolution of life.
The first unicellular organisms that arose on our planet were primitive bacteria that did not have a nucleus, that is, prokaryotes. As already mentioned, these were unicellular non-nuclear organisms. They were anaerobes, because they lived in an anoxic environment, and heterotrophs, because they ate ready-made organic compounds"organic soup", that is, substances synthesized in the course of chemical evolution. Energy metabolism in most prokaryotes occurred according to the type of fermentation. But gradually the "organic broth" as a result of active consumption subsided. As it was exhausted, some organisms began to develop ways to form macromolecules biochemically, inside the cells themselves with the help of enzymes. Under such conditions, the cells that were able to obtain most of the required energy directly from solar radiation turned out to be competitive. The process of chlorophyll formation and photosynthesis proceeded along this path.
The transition of living things to photosynthesis and autotrophic type of nutrition was a turning point in the evolution of living things. The Earth's atmosphere began to "fill up" with oxygen, which was poison for anaerobes. Therefore, many unicellular anaerobes died, others took refuge in anoxic environments - swamps and, eating, emitted not oxygen, but methane. Still others have adapted to oxygen. Their central exchange mechanism was oxygen respiration, which made it possible to increase the yield of useful energy by 10–15 times compared with the anaerobic type of metabolism - fermentation. The transition to photosynthesis was a long process and ended about 1.8 billion years ago. With the advent of photosynthesis, more and more energy was accumulated in the organic matter of the Earth. sunlight, which accelerated biological cycle substances and the evolution of living things in general.
Eukaryotes, that is, single-celled organisms with a nucleus, formed in an oxygen environment. These were already more perfect organisms with photosynthetic ability. Their DNA was already concentrated into chromosomes, whereas in prokaryotic cells, the hereditary substance was distributed throughout the cell. The eukaryotic chromosomes were concentrated in the cell nucleus, and the cell itself was already reproducing without significant changes. Thus, the eukaryotic daughter cell was almost an exact copy of the mother cell and had the same chance of survival as the mother cell.
Education of plants and animals
The subsequent evolution of eukaryotes was associated with the division into plant and animal cells. Such a division occurred in the Proterozoic, when the Earth was inhabited by unicellular organisms (Table 8.2).
Table 8.2
The emergence and distribution of organisms in the history of the Earth (according to Z. Brehm and I. Meinke, 1999)
Since the beginning of evolution, eukaryotes have developed dually, that is, they had parallel groups with autotrophic and heterotrophic nutrition, which ensured the integrity and significant autonomy of the living world.
Plant cells have evolved in the direction of reducing the ability to move due to the development of a rigid cellulose shell, but in the direction of using photosynthesis.
Animal cells have evolved to increase the ability to move, as well as to improve the way they absorb and excrete processed food.
The next stage in the development of living things was sexual reproduction. It originated about 900 million years ago.
The next step in the evolution of living things took place about 700-800 million years ago, when multicellular organisms appeared with a differentiated body, tissues and organs that perform certain functions. These were sponges, coelenterates, arthropods, etc., belonging to multicellular animals.
Throughout the Proterozoic and at the beginning of the Paleozoic, plants inhabited mainly the seas and oceans. These are green and brown, golden and red algae.
Subsequently, many types of animals already existed in the seas of the Cambrian. In the future, they specialized and improved. Among the marine animals of that time were crustaceans, sponges, corals, mollusks, trilobites, etc.
At the end of the Ordovician period, large carnivores, as well as vertebrates, began to appear.
Further evolution of vertebrates went in the direction of jawed fish. In the Devonian, lung-breathing fish began to appear - amphibians, and then insects. The nervous system gradually developed as a result of the improvement of the forms of reflection.
A particularly important stage in the evolution of living forms was the emergence of plant and animal organisms from water to land and a further increase in the number of species of land plants and animals. In the future, it is from them that highly organized forms of life originate. The emergence of plants on land began at the end of the Silurian, and the active conquest of land by vertebrates began in the Carboniferous.
The transition to life in the air required many changes from living organisms and involved the development of appropriate adaptations. He dramatically increased the rate of evolution of life on Earth. Man has become the pinnacle of the evolution of the living.
Life in the air has “increased” the body weight of organisms, the air does not contain nutrients, air transmits light, sound, heat differently than water, the amount of oxygen in it is higher. All this had to be adjusted. The first vertebrates to adapt to the conditions of life on land were reptiles. Their eggs were supplied with food and oxygen for the embryo, covered with a hard shell, and were not afraid of drying out.
Approximately 67 million years ago birds and mammals gained the advantage in natural selection. Thanks to the warm-bloodedness of mammals, they quickly gained a dominant position on Earth, which is associated with the conditions of cooling on our planet. At this time, it was warm-bloodedness that became the decisive factor in survival. It provided a constant high body temperature and the stability of the functioning of the internal organs of mammals. The live birth of mammals and the feeding of young with milk was a powerful factor in their evolution, allowing them to reproduce in a variety of environmental conditions. A developed nervous system contributed to a variety of forms of adaptation and protection of organisms.
There was a division of carnivores and ungulates into ungulates and predators, and the first insectivorous mammals marked the beginning of the evolution of placental and marsupial organisms.
The decisive stage in the evolution of life on our planet was the appearance of a detachment of primates. In the Cenozoic, approximately 67-27 million years ago, primates were divided into lower and anthropoid apes, which are the most ancient ancestors. modern man. The prerequisites for the emergence of modern man in the process of evolution were formed gradually. At first there was a herd way of life. He allowed to form the foundation of future social communication. Moreover, if in insects (bees, ants, termites) biosociality led to the loss of individuality, then in the ancient ancestors of man, on the contrary, it developed the individual traits of the individual. This was a powerful driving force behind the development of the team.
The evolution of life took its next step in the form of the emergence of Homo sapiens (Homo sapiens). It is a reasonable person who has the ability to purposefully change the world around him, create artificial conditions for his habitat and transform the appearance of our planet.
The evolutionary theory of Ch. Darwin
Under evolution (from lat. evolution- development, deployment) should be understood as a process of long-term, gradual, slow changes leading to fundamental qualitatively new changes (the formation of other structures, forms, organisms and their types).
The idea of a long and gradual change in all kinds of animals and plants was expressed by scientists long before Charles Darwin. It was in this spirit that different time Aristotle, Swedish naturalist C. Linnaeus, French biologist J. Lamarck, contemporary of Charles Darwin, English naturalist A. Wallace and other scientists.
The undoubted merit of Charles Darwin is not the idea of evolution itself, but the fact that it was he who first discovered the principle of natural selection in nature and generalized individual evolutionary ideas into one coherent theory of evolution. In the formation of his theory, Charles Darwin relied on a large amount of factual material, on experiments and the practice of selection work on the development of new varieties of plants and various breeds of animals.
At the same time, Charles Darwin came to the conclusion that from the many diverse phenomena of living nature, three fundamental factors in the evolution of living things are clearly distinguished, united by a short formula: variability, heredity, natural selection.
These fundamental principles are based on the following conclusions and observations on the living world - these are:
1. Variability. It is characteristic of any group of animals and plants, organisms differ from each other in many different ways. In nature, it is impossible to find two identical organisms. Variability is an inherent property of living organisms, it manifests itself constantly and everywhere.
According to Charles Darwin, there are two types of variability in nature - definite and indefinite.
1) Certain variability(adaptive modification) is the ability of all individuals of the same species in some specific environmental conditions to respond in the same way to these conditions (food, climate, etc.). According to modern concepts, adaptive modifications are not inherited, and therefore, for the most part, they cannot supply material for organic evolution.
2) Uncertain variability(mutation) causes significant changes in the body in a variety of ways. This variability, in contrast to a certain one, is hereditary in nature, while minor deviations in the first generation increase in subsequent ones. Uncertain variability is also associated with changes in the environment, but not directly, as in adaptive modifications, but indirectly. Therefore, according to Ch. Darwin, it is uncertain changes that play a decisive role in evolution.
2. The constant population of the species. The number of organisms of each species that are born is greater than the number that can find food and survive; nevertheless, the abundance of each species under natural conditions remains relatively constant.
3. Competitive relations of individuals. Since more individuals are born than can survive, in nature there is a constant struggle for existence, competition for food and habitat.
4. Adaptability, adaptability of organisms. Changes that make it easier for an organism to survive in a particular environment give their owners an advantage over other organisms that are less adapted to external conditions and, as a result, die. The idea of "survival of the fittest" is central to the theory of natural selection. 5. Reproduction of "successful" acquired characteristics in offspring. Surviving individuals produce offspring, and thus "successful", positive changes that made it possible to survive are transmitted to subsequent generations.
The essence of the evolutionary process is the continuous adaptation of living organisms to various environmental conditions and the emergence of more and more complex organisms. Therefore, biological evolution is directed from simple biological forms to more complex forms.
Thus, natural selection, which is the result of the struggle for existence, is the main factor in evolution that directs and determines evolutionary changes. These changes become noticeable, passing through the change of many generations. It is in natural selection that one of the fundamental features of the living is reflected - the dialectic of the interaction between the organic system and the environment.
The undoubted advantages of Charles Darwin's evolutionary theory also had some disadvantages. So, she could not explain the reasons for the appearance in some organisms of certain structures that seem useless; many species lacked transitional forms between modern animals and fossils; weak point were also ideas about heredity. Subsequently, shortcomings were discovered concerning the main causes and factors of organic evolution. Already in the XX century. it became clear that the theory of Ch. Darwin needed further refinement and improvement, taking into account the latest achievements of biological science. This became a prerequisite for the creation of a synthetic theory of evolution (STE).
Synthetic theory of evolution
Achievements in genetics in uncovering the genetic code, advances in molecular biology, embryology, evolutionary morphology, popular genetics, ecology and some other sciences point to the need for a connection modern genetics with the theory of evolution of Charles Darwin. Such an association gave rise in the second half of the 20th century. new biological paradigm - the synthetic theory of evolution. Since it is based on the theory of Charles Darwin, it is called neo-Darwinist. This theory is considered as non-classical biology. The synthetic theory of evolution made it possible to overcome the contradictions between evolutionary theory and genetics. STE does not yet have a physical model of evolution, but is a multifaceted complex doctrine that underlies modern evolutionary biology. This synthesis of genetics and evolutionary doctrine was a qualitative leap both in the development of genetics itself and in modern evolutionary theory. This leap marked the creation of a new center of the system of biological knowledge and the transition of biology to the modern non-classical level of its development. STE is often called the general theory of evolution, which is a combination of evolutionary ideas of Charles Darwin, mainly natural selection, with modern research results in the field of heredity and variability.
The main ideas of STE were laid down by the Russian geneticist S. Chetverikov as early as 1926 in his works on popular genetics. These ideas were supported and developed by the American geneticists R. Fisher, S. Wright, the English biologist and geneticist D. Haldane, and the contemporary Russian geneticist N. Dubinin (1906–1998).
The main prerequisite for the synthesis of genetics with the theory of evolution were biometric and physical and mathematical approaches to the analysis of evolution, the chromosome theory of heredity, empirical studies of the variability of natural populations, etc.
The reference point of STE is the idea that the elementary component of evolution is not a species (according to Darwin) and not an individual (according to Lamarck), but a population. It is she who is an integral system of interconnection of organisms, which has all the data for self-development. The selection is subjected not to some individual traits or individuals, but to the entire population, its genotype. However, this selection is carried out by changing the phenotypic traits of individual individuals, which leads to the emergence of new traits when changing biological generations.
The basic unit of heredity is the gene. It is a section of a DNA molecule (or chromosome) that determines the development of certain signs of an organism. Soviet geneticist N. V. Timofeev-Resovsky (1900–1981) formulated a position on the phenomena and factors of evolution. It is as follows:
The main determining factor in the synthetic theory of evolution is natural selection, which directs the evolutionary process. Purely biological significance an individual as an organism that has given offspring is estimated by its contribution to the gene pool of the population. The objects of selection in a population are the phenotypes of individual individuals. The phenotype of an individual organism is determined and formed on the basis of the realized information of the genotype in changing environmental conditions. As a result, from generation to generation, selection for phenotypes leads to the selection of genotypes.
Evolution is a single process. In STE, two levels of evolution are distinguished: microevolution passing at the population-species level in a relatively short time in limited areas, and macroevolution, passing at the subspecies level, where general patterns and trends in the historical development of the living are manifested.
microevolution is a set of evolutionary processes occurring in populations of a species, leading to changes in the gene pools of these populations and to the formation of new species. It occurs on the basis of mutational variability under the strict control of natural selection. Mutations are the only source of qualitatively new traits. Selection is a creative selective factor that directs elementary evolutionary changes along the path of adaptation of organisms to changing environmental conditions. The nature of the processes of microevolution is influenced by changes in the number of populations (waves of life), the exchange of genetic information between them, as well as isolation. Microevolution leads either to a change in the entire gene pool of the species as a whole (phylogenetic evolution), or to their isolation from the parent original species as already new forms (speciation).
macroevolution- these are evolutionary transformations that lead to a change in a higher level of taxa than the species (families, orders, classes). It does not have its characteristic mechanisms and is carried out through the processes of microevolution. Gradually accumulating, microevolutionary processes receive their external expression in the phenomena of macroevolution. Macroevolution is a generalized picture of evolutionary change observed in a broad historical perspective. Therefore, only at the level of macroevolution, general tendencies, patterns and directions of the evolution of living nature are manifested, which cannot be observed at the microevolutionary level.
Modern concepts of STE indicate that evolutionary changes are random and undirected, since random mutations are the source material for them. Evolution proceeds gradually and divergently through the selection of small random mutations. At the same time, new life forms are formed through major hereditary changes, the right to life of which is determined by natural selection. A slow and gradually ongoing evolutionary process can also have a spasmodic character associated with changes in environmental conditions as a result of the bifurcation processes of the development of our planet.
The synthetic theory of evolution is not some kind of canon, a frozen system of theoretical positions. In its possible range, new areas of research are being formed, fundamental discoveries are appearing and will continue to appear, contributing to further knowledge of the evolutionary processes of living things.
According to modern concepts, an important practical task of STE is to develop optimal ways to control the evolutionary process in the face of constantly increasing anthropogenic pressure on the natural environment. This theory is used in solving problems of the relationship between man and nature, nature and human society.
However, the synthetic theory of evolution has some controversial points and difficulties that give rise to non-Darwinian concepts of evolution. These include, for example, the theory of nomogenesis, the concept of punctualism, and some others.
The theory of nomogenesis was proposed in 1922 by the Russian biologist L. Berg. It is based on the notion that evolution is already a programmed process of realizing internal patterns inherent in living things. A certain internal force of nature is inherent in a living organism, which always acts, regardless of external conditions, purposefully towards the complication of living structures. In support of this, L. Berg pointed to some data on the convergent and parallel evolution of certain groups of plants and animals.
One recent non-Darwinian concept is punctualism. Proponents of this direction believe that the process of evolution proceeds in leaps and bounds - through rare and fast jumps, which account for only 1% of evolutionary time. The remaining 99% of the time of its existence, the species is in a state of stability. In extreme cases, the leap to a new species may occur in small populations of only ten individuals within one or more generations. This concept is based on the genetic base laid down by molecular genetics and modern biochemistry. Punctualism rejects the genetic-population model of speciation, Charles Darwin's idea of varieties and subspecies as emerging species. Punctualism has focused its attention on the molecular genetics of the individual as the bearer of the properties of the species. The idea of disunity between macro- and microevolution and the independence of the factors controlled by them gives this concept a certain value.
It is likely that in the future a unified theory of life may emerge that combines the synthetic theory of evolution with non-Darwinian concepts of the development of living nature.
Evolutionary picture of the world. Global evolutionism
The idea of world development is the most important idea of world civilization. In its far from perfect forms, it began to penetrate into natural science as early as the 18th century. But already in the nineteenth century can be safely called the age of ideas of evolution. At this time, the concepts of development began to penetrate into geology, biology, sociology and the humanities. In the first half of the XX century. science recognized the evolution of nature, society, man, but the philosophical general principle of development was still absent.
And only by the end of the 20th century, natural science acquired a theoretical and methodological basis for creating a unified model of universal evolution, identifying universal laws of direction and driving forces of the evolution of nature. Such a basis is the theory of self-organization of matter, which represents synergetics. (As mentioned above, synergetics is the science of the organization of matter.) The concept of universal evolutionism, which has reached the global level, linked the origin of the Universe (cosmogenesis), the emergence of the solar system and the planet Earth (geogenesis), the emergence of life (biogenesis) into a single whole , man and human society (anthroposociogenesis). Such a model of the development of nature is also called global evolutionism, since it covers all the existing and mentally represented manifestations of matter in a single process of self-organization of nature.
Global evolutionism should be understood as the concept of the development of the Universe as a natural whole developing in time. At the same time, the entire history of the Universe, starting from the Big Bang and ending with the emergence of mankind, is considered as a single process, where the cosmic, chemical, biological and social types of evolution are successively and genetically closely interconnected. Space, geological and biological chemistry in a single process of evolution of molecular systems reflects their fundamental transitions and the inevitability of transformation into living matter. Consequently, the most important regularity of global evolutionism is the direction of development of the world whole (universe) to increase its structural organization.
In the concept of universal evolutionism, the idea of natural selection plays an important role. Here, the new always arises as a result of the selection of the most effective shaping. Ineffective neoplasms are rejected by the historical process. A qualitatively new level of the organization of matter is "asserted" by history only when it turns out to be capable of absorbing the previous experience of the historical development of matter. This pattern is especially pronounced for the biological form of motion, but it is characteristic of the entire evolution of matter in general.
The principle of global evolutionism is based on understanding the internal logic of the development of the cosmic order of things, the logic of the development of the Universe as a whole. For this understanding, an important role is played by anthropic principle. Its essence is that consideration and knowledge of the laws of the universe and its structure is carried out by a reasonable person. Nature is what it is only because there is a person in it. In other words, the laws of construction of the Universe must be such that it will certainly give rise to an observer someday; if they were different, there would simply be no one to know the Universe. The anthropic principle indicates the internal unity of the patterns of the historical evolution of the Universe and the prerequisites for the emergence and evolution of living matter up to anthroposociogenesis.
The paradigm of universal evolutionism is a further development and continuation of various ideological pictures of the world. As a result, the very idea of global evolutionism has an ideological character. Its leading goal is to establish the direction of the processes of self-organization and development of processes on the scale of the Universe. In our time, the idea of global evolutionism plays a dual role. On the one hand, it represents the world as an integrity, allows you to comprehend the general laws of being in their unity; on the other hand, orientate modern natural science to identify certain regularities in the evolution of matter at all structural levels its organization and at all stages of its self-development.
The concept of evolutionism 1. The concept of "evolution". 2. Basic postulates of the concept of evolution of the organic world. 3. Principles of global evolutionism.
The concept of "evolution" 1. Evolutionary theory is no longer considered as a unified description of an unambiguous path of development, which is known to the end by science, rather, evolutionism in modern science is a spectrum of substantiated concepts to varying degrees. 2. Evolution implies a general gradual development, ordered and consistent.
The concept of "evolution" By the second half of the XVIII century, there were objective prerequisites for the emergence of scientifically based evolutionary views: descriptions of many new species as a result of geographical discoveries; the unity of the structural plan of many previously known groups of organisms was established; the emergence of a special biological discipline - paleontology; the emergence of scientifically based theories of the origin of the Earth and the solar system
The concept of "evolution". At the turn of the 18th and 19th centuries, revealing the patterns of the historical development of the plant and animal world became a top priority.
The main postulates of the concept of evolution of the organic world. French biologist Jean-Baptiste Lamarck (1744 - 1829) put forward a hypothesis about the mechanism of evolution. He published his views, which are now considered the essence of Lamarckism, in his Philosophy of Zoology in 1809. The implementation of the principle of gradation, according to Lamarck, becomes possible due to the presence in organisms of an internal desire for improvement.
The main postulates of the concept of evolution of the organic world. The main generalization of Lamarck's views are two provisions that entered the history of science under the name "Lamarck's laws". 1. In all animals that have not reached the limit of their development, organs and organ systems that have been subjected to prolonged intense exercise gradually increase in size and become more complex, while those that are not exercised become simpler and disappear. 2. Characteristics and properties acquired as a result of long-term and stable exposure to the external environment are inherited and preserved in offspring, provided that both parental organisms have them.
The main postulates of the concept of evolution of the organic world. Lamarck's concept was the first complete system of evolutionary views and at the same time the first attempt to substantiate these views. Lamarck, on the whole, correctly characterized evolution as a progressive process going in the direction of complicating the structure of organisms. Lamarck's views on the adaptive nature of the evolutionary process were advanced for their time. Lamarck's concept contained a number of erroneous provisions: 1. an explanation of the evolutionary process as the result of an internal desire for improvement. 2. the assumption of the possibility of the appearance of inherited adaptive traits in response to the influence of the environment. 3. denial of the reality of the species.
The main postulates of the concept of evolution of the organic world. Charles Darwin's theory of evolution is considered one of the main scientific revolutions, since, in addition to purely scientific significance, it led to a revision of a wide range of philosophical, ethical, and social problems.
The main postulates of the concept of evolution of the organic world. Charles Darwin's theory of evolution has several scientific components. 1. The idea of evolution as a reality, which means defining life as a dynamic structure of the natural world, and not a static system. 2. As a result of excess fertility between organisms in nature, competition for habitat and food arises - a "struggle for existence". It is customary to distinguish three of its forms: the fight against factors of non-biological (abiotic) origin, interspecific and intraspecific struggle.
The main postulates of the concept of evolution of the organic world. Due to the presence of variability, different individuals in the process of struggle for existence find themselves in an unequal position. Individual changes that facilitate survival provide their carriers with an advantage, as a result of which individuals more adapted to the conditions survive and produce offspring more often, and the weaker individuals are more likely to die or be eliminated from interbreeding. Darwin called this phenomenon natural selection.
The main postulates of the concept of evolution of the organic world. The adaptive nature of evolution is achieved by selecting from a variety of random changes those that facilitate survival in given, specific environmental conditions. The fitness of organisms is, as a rule, relative.
The main postulates of the concept of evolution of the organic world. The position that species originated by natural selection, Darwin derived, based on five basic postulates: 1. All species have the biological potential to increase the number of individuals to large populations. 2. Populations in nature demonstrate the relative constancy of the number of individuals over time. 3. The resources necessary for the existence of species are limited, so the number of individuals in populations is approximately constant over time. Conclusion 1. Between representatives of the same species there is a struggle for the resources necessary for survival and reproduction. Only a small fraction of individuals survive and reproduce.
The main postulates of the concept of evolution of the organic world. 4. There are no two individuals of the same species that would have the same properties. Representatives of the same species show great variability. 5. Basically, variability is genetically determined, therefore it is inherited. Conclusion 2. Competition between representatives of the same species depends on the unique hereditary properties of individuals that provide advantages in the struggle for resources for survival and reproduction. This unequal ability to survive is natural selection. Conclusion 3. The accumulation of more favorable properties as a result of natural selection leads to a constant change in species. This is how evolution happens.
Evidence for the Evolutionary Concept The evidence supporting the current understanding of evolution comes from a variety of sources. Some of the events cited as evidence for evolutionary theory can be reproduced in the laboratory, however, this does not mean that they really took place in the past, they simply indicate the possibility of such events.
Evidence for the evolutionary concept. Systematics Natural classification can be phylogenetic or phenotypic. Phylogenetic classification is more often used, since it reflects evolutionary relationships based on the origin of organisms and the inheritance of certain characteristics by them. Similarities and differences between organisms can be explained as the result of progressive adaptation of organisms within each taxonomic group to certain environmental conditions over a period of time.
Evidence for the evolutionary concept. The following basic hierarchical units are used in taxonomy: Kingdom; Type (department in plants); Class; Detachment (order in plants); Family; Genus; View. Each taxon may contain several taxonomic units of lower rank. But at the same time, a taxon can belong to only one taxon located immediately above it. Each hierarchical level may contain several taxa, but they all differ from each other.
Evidence for the evolutionary concept. Comparative anatomy As evidence of the origin of animals from a common ancestor, the presence of homologous and rudimentary organs is considered. The nictitating membrane is a "rudiment" of a person.
The concept of catastrophism Catastrophist hypotheses can be divided into two main groups. 1. Terrestrial catastrophism: catastrophes are associated with geological processes (revival of volcanism, leading to global cooling and the release of large volumes of toxic substances into the atmosphere, mountain building processes associated with climate change).
the concept of catastrophism 2. Cosmic catastrophism: catastrophes are of cosmic origin: a catastrophic increase in radiation caused by a supernova explosion; fluctuations in solar activity; bombardment of the Earth by comets and giant asteroids, associated with fluctuations in the position of the solar system relative to the plane of the galaxy; passing a major celestial body through the comet cloud surrounding the solar system.
The concept of catastrophism In 1980, an American physicist, laureate Nobel Prize L. Alvarez and his son, geologist U. Alvarez, suggested that the iridium anomaly is the result of a large asteroid hitting the Earth, the substance of which was scattered over the entire earth's surface. This led to a complete short-term suspension of photosynthesis and the mass death of green plants, and after green plants, the death of herbivorous animals, followed by predators.
The concept of catastrophism None of the catastrophic models explains the meaning of the processes that took place on Earth in critical epochs, but rather raises new questions. Psychological factors (the novelty of the idea of asteroids) play an important role in the spread of alternative, anti-Darwinian concepts of evolution.
The ratio of micro- and macroevolution. Microevolution is a set of evolutionary processes that occur in populations of a species and lead to a change in the gene pool of these populations and the formation of new species. Macroevolution - evolutionary transformations leading to the formation of taxa of a higher rank than the species.
The concept of evolution Evolution is a process of long-term and gradual changes that lead to fundamental qualitative changes in living organisms, accompanied by the emergence of new biological systems, forms and species. Based on historical method evolutionary theory, whose task is to study the factors, driving forces and patterns of organic evolution, occupies a central place in the system of sciences about living nature.
History of development of evolutionary ideas Two points of view explaining the diversity of species in wildlife: The first of them arose on the basis of ancient dialectics, which affirmed the idea of development and change in the surrounding world; The second point of view appeared along with the Christian worldview based on the ideas of creationism.
The most important achievements of antiquity and modern times Aristotle "On parts of animals" - the idea of "ladder of living beings"; Carl Linnaeus and his classification of species; The formation of the doctrine of "transformism" - the idea of variability of species of organisms under the influence of environmental changes in the absence of a holistic and consistent concept of evolution.
The concept of development of J. B. Lamarck Three questions: 1) What is the basic unit of evolution? 2) What are the factors and driving forces (1744-1829) of evolution? 3) How is the transmission of newly acquired traits to the next generations?
The unit of evolution according to Lamarck The unit of evolution is the organism. Lamarck's evolutionary theory was based on the concept of development, gradual and slow, from simple to complex, taking into account the role of the external environment in the transformation of organisms. Lamarck believed that the first spontaneously generated organisms gave rise to the whole variety of organic forms that currently exist. Development from the simplest to the most perfect organisms is the main content of the history of the organic world.
Factors and driving forces of evolution Inherent in living nature, the original (laid by the Creator) desire for the complication and self-improvement of its organization; the influence of the external environment and living conditions: nutrition, climate, soil characteristics, moisture, temperature, etc.
The mechanism of transmission of acquired characteristics to the next generations The mechanism of heredity: individual changes, if they are repeated in a number of generations, are transmitted by inheritance to descendants during reproduction and become signs of the species; at the same time, if some organs of animals develop, then others, not involved in the process of changes, atrophy.
The theory of catastrophes by J. Cuvier Identification of the principle of correlations - each part of the body reflects the principles of the structure of the whole organism. The development of the theory of catastrophes - Cuvier came to the conclusion that gigantic cataclysms periodically occurred on Earth, destroying entire continents, and with them their inhabitants. Later, new organisms appeared in their place.
Ch. Darwin's Theory of Evolution Darwin formulated the main provisions of his theory of evolution and presented them in the book "The Origin of Species by Means of Natural Selection" (1859). (1809 - 1882)
The main driving factors of evolution in Darwin's theory Factors: Variability; Heredity; Struggle for existence; Natural selection.
Variability A certain (group) variability is a similar change in all individuals of the offspring in one direction due to the influence of certain conditions. \u003d modification Indefinite (individual) variability - the appearance of various minor differences in individuals of the same species, by which one individual differs from others. = mutation
Heredity is the property of organisms to ensure the continuity of signs and properties between generations, as well as to determine the nature of the development of an organism in specific environmental conditions. In the process of reproduction, not traits are transmitted from generation to generation, but a code of hereditary information (the norm of the reaction of a developing individual to the action of the external environment), which determines only the possibility of developing future traits in a certain range.
The struggle for existence is a set of relationships between organisms of a given species with each other, with other types of living organisms and inanimate environmental factors. Darwin singled out three main forms of struggle for existence: 1) interspecific, 2) intraspecific, 3) struggle with adverse environmental conditions.
Natural selection is a set of changes occurring in nature that ensure the survival of the fittest individuals and their predominant offspring, as well as the selective destruction of organisms that are unadapted to existing or changed environmental conditions.
Disadvantages of Darwin's theory According to the theory of evolution, mutations should occur very often, and for the most part they should be beneficial (in reality, almost all mutations are harmful) or, in extreme cases, useless; Also, according to the theory of evolution, in one place and at one time there should be two individuals of the same species and with the same mutations, and they should be of different sexes. They must survive, interbreed, and their descendants must have the same mutant features (descendants must also survive, find the same mutant of the opposite sex, etc.). So far, this has never happened in the natural environment.
Disadvantages of Darwin's theory The following questions also fell out of the field of view of Darwinists: About the reasons for the preservation of the systemic unity of organisms in the historical development; On the mechanisms of inclusion in the evolutionary process of ontogenetic rearrangements; On the uneven pace of evolution; On the causes and mechanisms of biotic crises, etc. In addition, there is no evidence that man descended from a monkey, since not a single evidence (fossil) has been found confirming the existence of an intermediate stage between man and ape.
Neo-Lamarckism mechanolamarckism - this concept explained the evolutionary transformations of organisms by their original ability to respond appropriately to changes in the external environment, while changing their structures and functions; psycho-Lamarckism - evolution was presented as a gradual strengthening of the role of consciousness in the movement from primitive beings to intelligent life forms; ortholamarckism - the direction of evolution is due to the internal initial properties of organisms.
The concept of teleogenesis This concept is ideologically close to ortholamarckism, as it comes from Lamarck's idea of the inner striving of all living organisms for progress. Within the concept of teleogenesis, the doctrine of saltationism stands out, according to which all major evolutionary events - from the emergence of new species to the change of biota in the geological history of the Earth - occur as a result of spasmodic changes, saltations, or macromutations.
Genetic anti-Darwinism At the beginning of the 20th century. genetics arose - the doctrine of heredity and variability; The spread of anti-evolutionism (W. Betson), according to which mutational variability was identified with evolutionary transformations, which eliminated the need for selection as the main cause of evolution.
The theory of nomogenesis L. S. Berg's theory of nomogenesis, created in 1922, was based on the idea that evolution is a programmed process of realizing internal patterns inherent in all living things (1876-1950). Berg believed that organisms have an internal force of an unknown nature, acting purposefully, regardless of the external environment, in the direction of complicating the organization.
Synthetic theory of evolution = general theory evolution = neo-Darwinism is the theory of organic evolution by natural selection of traits determined genetically. The elementary evolutionary structure is the population; An elementary evolutionary phenomenon is a change in the genotypic composition of a population; The elementary hereditary material is the gene pool of the population; The elementary evolutionary factors are mutational processes, population waves numbers, isolation and natural selection.
Concepts of micro- and macroevolution Microevolution is understood as a set of evolutionary processes occurring in populations, leading to changes in the gene pool of these populations and the formation of new species. Macroevolution is understood as evolutionary transformations leading to the formation of taxa of a higher rank than the species (genera, orders, classes).
The main provisions of STE 1. The main factor of evolution is natural selection, integrating and regulating the action of all other factors (mutagenesis, hybridization, migration, isolation, etc.); 2. Evolution proceeds divergently, gradually, through the selection of random mutations, and new forms are formed through hereditary changes; 3. Evolutionary changes are random and undirected; the source material for them are mutations; the original organization of the population and changes in external conditions limit and direct hereditary changes; 4. Macroevolution leading to the formation of supraspecific groups is carried out only through microevolutionary processes, and there are no specific mechanisms for the emergence of new life forms.
The evolution of the organic world of the Earth is inextricably linked with the evolution of the lithosphere. The history of the development of the Earth's lithosphere is divided into geological eras: Catharhean, Archean, Proterozoic, Paleozoic, Mesozoic, Cenozoic. Each era is divided into periods and epochs. Geological eras, periods and epochs correspond to certain stages in the development of life on Earth.
Catarchean, Archean and Proterozoic unite to form cryptozoic- "the era of hidden life." The fossil remains of the Cryptozoic are represented by separate fragments that are not always identifiable. Paleozoic, Mesozoic, and Cenozoic combine to form phanerozoic- "the era of manifest life." The beginning of the Phanerozoic is characterized by the appearance of skeleton-forming animals that are well preserved in the fossil state: foraminifera, shell mollusks, and ancient arthropods.
Early stages of development of the organic world
Under conditions of an excess of ready-made organic substances, the heterotrophic (saprotrophic) mode of nutrition is primary. B about Most of the archebionts specialized specifically in heterotrophic saprotrophic nutrition. They form complex enzyme systems. This led to an increase in the amount of genetic information, the appearance of a nuclear membrane, a variety of intracellular membranes and organelles of movement. Some heterotrophs undergo a transition from saprotrophic supply to holozoic. Subsequently, histone proteins appear, which made possible the appearance of true chromosomes and perfect methods of cell division: mitosis and meiosis. Thus, there is a transition from prokaryotic type of cell organization to eukaryotic.
Another part of the archebionts specialized in autotrophic nutrition. The oldest method of autotrophic nutrition is chemosynthesis. On the basis of enzyme-transport systems of chemosynthesis arises photosynthesis- a set of metabolic processes based on the absorption of light energy using a variety of photosynthetic pigments (bacteriochlorophyll, chlorophylls a, b, c, d and others). An excess of carbohydrates formed during CO 2 fixation made it possible to synthesize various polysaccharides.
All of the above traits in heterotrophs and autotrophs are large aromorphoses.
Probably, in the early stages of the evolution of the organic world of the Earth, the exchange of genes between completely different organisms (gene transfer by transduction, interspecific hybridization and intracellular symbiosis) was widespread. In the course of synthesisgenesis, the properties of heterotrophic and photoautotrophic organisms were combined in one cell. This led to the formation of various divisions of algae - the first true plants.
The main stages of plant evolution
Algae are a numerous heterogeneous group of primary aquatic photoautotrophic organisms. In the fossil state, algae are known from the Precambrian (over 570 million years ago), and in the Proterozoic and early Mesozoic, all now known divisions already existed. None of the modern divisions of algae can be considered the ancestor of another division, indicating reticulated character algae evolution.
At the end of the Silurian (≈ 400 million years ago), higher(ground) plants.
In the Silurian, the shallowing of the ocean and desalination of water took place. This created the prerequisites for the settlement of the littoral and supralittoral zones ( littoral- part of the coast, flooded during high tides; the littoral occupies an intermediate position between aquatic and terrestrial-air habitats; supralittoral- part of the coast above the level of the tides, moistened by spray; in essence, the supralittoral is part of the terrestrial-air habitat).
The oxygen content in the atmosphere before the appearance of terrestrial plants was significantly lower than the modern one: Proterozoic - 0.001 of the current level, Cambrian - 0.01, Silurian - 0.1. When oxygen is deficient, the limiting factor in the atmosphere is ultraviolet. The emergence of plants on land was accompanied by the development of the metabolism of phenolic compounds (tannins, flavonoids, anthocyanins), which are involved in the implementation of protective reactions, including against mutagenic factors (ultraviolet, ionizing radiation, some chemicals).
The advancement of plants on land is associated with the appearance of a number of aromorphoses:
1) The appearance of differentiated tissues: integumentary, conductive, mechanical, photosynthetic. The appearance of differentiated tissues is inextricably linked with the appearance of meristems and the main parenchyma.
2) The appearance of differentiated organs: a shoot (an organ of carbon nutrition) and a root (an organ of mineral nutrition).
3) Multicellular gametangia appear: antheridia and archegonia.
4) There are significant changes in metabolism.
The ancestors of higher plants are organisms similar to modern Chara algae. The oldest known land plant is the cooksonia. Cooksonia was discovered in 1937 (W. Lang) in the Silurian sandstones of Scotland (about 415 million years old). This plant was an algae-like cluster of twigs bearing sporangia. Attached to the substrate with rhizoids.
The further evolution of higher plants was divided into two lines: gametophyte and sporophyte.
Representatives of the gametophyte line are modern Bryophytes. This is avascular plants, which lack specialized conductive and mechanical tissues.
Another line of evolution led to the emergence vascular plants, in which the sporophyte dominates in the life cycle, and there are all tissues of higher plants (educational, integumentary, conductive, the main parenchyma and its derivatives). Due to the appearance of all types of tissues, the body of plants is differentiated into a root and a shoot. The oldest of the vascular plants are now extinct Rhynia(psilophytes). During the Devonian, modern groups are formed spore plants(mosses, horsetails, ferns). However, in spore plants missing seed, and the sporophyte develops from an undifferentiated embryo.
At the beginning of the Mesozoic (≈ 220 million years ago), the first Gymnosperms that dominated the Mesozoic era. The largest aromorphoses of gymnosperms:
1) Appearance ovules; The female gametophyte (endosperm) develops in the ovule.
2) Appearance pollen grains; in most species, the pollen grain forms a pollen tube upon germination, forming the male gametophyte.
3) Appearance seed, which includes a differentiated embryo.
However, gymnosperms retain a number of primitive traits: the ovules are located openly on the seed scales (megasporangiophores), pollination occurs only with the help of the wind (anemophilia), the endosperm is haploid (female gametophyte), and the conducting tissues are primitive (tracheids are part of the xylem).
First Angiosperms(Flowering)plants probably appeared in the Jurassic period, and in the Cretaceous period their adaptive radiation. Angiosperms are currently in a state of biological progress, facilitated by a number of aromorphoses:
1) Appearance pestle- a closed carpel with ovules.
2) Appearance perianth, which made possible the transition to entomophily (pollination by insects).
3) Appearance embryo sac and double fertilization.
Currently, angiosperms are represented by many life forms: trees, shrubs, lianas, annual and perennial herbs, aquatic plants. The structure of the flower reaches a special diversity, which contributes to the accuracy of pollination and ensures intensive speciation - about 250 thousand plant species belong to Angiosperms.
The main stages of animal evolution
Eukaryotic organisms specialized in heterotrophic nutrition gave rise to Animals and mushrooms.
All known types appear in the Proterozoic era. Multicellular invertebrates. There are two main theories of the origin of multicellular animals. According to the theory gastrea(E. Haeckel), the initial method for the formation of a two-layer embryo is invagination (invagination of the blastula wall). According to the theory phagocytella(I. I. Mechnikov), the initial way of forming a two-layer embryo is immigration (movement of individual blastomeres into the cavity of the blastula). Perhaps these two theories complement each other.
Coelenterates- representatives of the most primitive (two-layer) multicellular: their body consists of only two layers of cells: ectoderm and endoderm. The level of tissue differentiation is very low.
In lower worms ( flat and roundworms) a third germ layer appears - the mesoderm. This is a major aromorphosis, due to which differentiated tissues and organ systems appear.
Then the evolutionary tree of animals branches into Protostomes and Deuterostomes. Among Protostomes, annelids a secondary body cavity is formed ( in general). This is a large aromorphosis, thanks to which it becomes possible to divide the body into sections.
Annelids have primitive limbs (parapodia) and homonomous (equivalent) body segmentation. But at the beginning of the Cambrian appear arthropods, in which the parapodia are transformed into jointed limbs. In Arthropods, a heteronomous (unequal) segmentation of the body appears. They have a chitinous exoskeleton, which contributes to the appearance of differentiated muscle bundles. The listed features of Arthropods are aromorphoses.
The most primitive arthropods trilobites dominated the Paleozoic seas. Modern Gill-breathing primary aquatic arthropods are represented crustaceans. However, at the beginning of the Devonian (after the landmass of plants and the formation of terrestrial ecosystems), landfall occurs. arachnids and insects.
Arachnids came to land thanks to numerous allomorphoses (idioadaptations):
1) Impermeability of covers for water.
2) Loss of larval stages of development (with the exception of ticks, but the tick nymph does not fundamentally differ from adult animals).
3) Formation of a compact weakly dissected body.
4) Formation of respiratory and excretory organs corresponding to new living conditions.
Insects are most adapted to life on land, due to the appearance of large aromorphoses:
1) The presence of embryonic membranes - serous and amniotic.
2) The presence of wings.
3) Plasticity of the oral apparatus.
With the advent of flowering plants in the Cretaceous period, the joint evolution of insects and flowering plants begins ( coevolution), and they form joint adaptations ( co-adaptation). In the Cenozoic era, insects, like flowering plants, are in a state of biological progress.
Among the deuterostomes, the highest flourishing reach chordate animals, in which a number of large aromorphoses appear: a chord, a neural tube, an abdominal aorta (and then a heart).
The origin of the chord has not yet been precisely established. It is known that strands of vacuolated cells are found in lower invertebrates. For example, in the eyelash worm Coelogynopora the intestinal branch, located above the nerve ganglia at the anterior end of the body, consists of vacuolated cells, so that an elastic rod appears inside the body, which helps to drill into the sandy soil. In the North American eyelash worm Nematoplana nigrocapitula in addition to the described foregut, the entire dorsal side of the intestine is transformed into a tourniquet consisting of vacuolated cells. This organ was called the intestinal chord (chordaintestinalis). It is possible that the dorsal chord (chordadorsalis) of entomesodermal origin arose directly from the vacuolated cells of the dorsal side of the intestine.
From primitive chordate animals in the Silurian the first Vertebrates(Jawless). In vertebrates, an axial and visceral skeleton is formed, in particular, the braincase and jaw region of the skull, which is also an aromorphosis. Inferior jawed vertebrates are diverse Pisces. Modern classes of fish (cartilaginous and bony) are formed at the end of the Paleozoic - the beginning of the Mesozoic).
Part of the Bony Fishes (Meaty-lobed), thanks to two aromorphoses - pulmonary respiration and the appearance of real limbs - gave rise to the first Quadruped–Amphibians(Amphibians). The first amphibians came to land in the Devonian period, but their heyday falls on the Carboniferous period (numerous stegocephalians). Modern Amphibians appear at the end of the Jurassic period.
In parallel, among the Tetrapods, organisms with embryonic membranes appear - amniotes. The presence of embryonic membranes is a large aromorphosis that first appears in reptile. Thanks to the embryonic membranes, as well as a number of other signs (keratinized epithelium, pelvic kidneys, the appearance of the cerebral cortex), Reptiles completely lost their dependence on water. The appearance of the first primitive reptiles cotylosaurs- refers to the end of the Carboniferous period. Various groups of reptiles appear in Perm: animal-toothed, primal lizards and others. At the beginning of the Mesozoic, branches of turtles, plesiosaurs, and ichthyosaurs are formed. The reptiles are on the rise.
Two branches are separated from groups close to the primary lizards evolutionary development. One branch at the beginning of the Mesozoic gave rise to a large group pseudosuch. Pseudosuchia gave rise to several groups: crocodiles, pterosaurs, ancestors of birds and dinosaurs, represented by two branches: lizards (Brontosaurus, Diplodocus) and ornithischians (only herbivorous species - Stegosaurus, Triceratops). The second branch at the beginning of the Cretaceous period led to the appearance of a subclass scaly(lizards, chameleons and snakes).
However, the Reptiles could not lose their dependence on low temperatures: warm-bloodedness is impossible for them due to incomplete separation of the circulatory circles. At the end of the Mesozoic, with climate change, there is a mass extinction of reptiles.
Only in a part of pseudosuchia in the Jurassic period does a complete septum appear between the ventricles, the left aortic arch is reduced, complete separation of the circulation occurs, and warm-bloodedness becomes possible. Subsequently, these animals acquired a number of adaptations for flight and gave rise to the class Birds.
In the Jurassic deposits of the Mesozoic era (≈ 150 million years ago), imprints of the First Birds were found: Archeopteryx and Archeornis (three skeletons and one feather). They were probably tree-climbing animals that could glide but were not capable of active flight. Even earlier (at the end of the Triassic, ≈ 225 million years ago), protoavis existed (two skeletons were discovered in 1986 in Texas). The skeleton of protoavis differed significantly from the skeleton of reptiles, large hemispheres brain and cerebellum were enlarged in size. In the Cretaceous period, there were two groups of fossil birds: Ichthyornis and Hesperornis. Modern groups of birds appear only at the beginning of the Cenozoic era.
The emergence of a four-chambered heart in combination with a reduction in the left aortic arch can be considered a significant aromorphosis in the evolution of birds. There was a complete separation of arterial and venous blood, which made possible the further development of the brain and a sharp increase in the level of metabolism. The heyday of birds in the Cenozoic era is associated with a number of major idioadaptations (appearance of feather cover, specialization of the musculoskeletal system, development of the nervous system, care for offspring and the ability to fly), as well as a number of signs of partial degeneration (for example, loss of teeth).
At the beginning of the Mesozoic era, the first mammals which arose due to a number of aromorphoses: enlarged forebrain hemispheres with a developed cortex, four-chambered heart, reduction of the right aortic arch, transformation of the suspension, quadrate and articular bones into auditory ossicles, the appearance of a coat, mammary glands, differentiated teeth in the alveoli, preoral cavity. The ancestors of Mammals were primitive Permian Reptiles, which retained a number of features of Amphibians (for example, skin glands were well developed).
In the Jurassic period of the Mesozoic era, Mammals were represented by at least five classes (Multituberous, Trituberculate, Tricodonts, Symmetrodonts, Panthotheres). One of these classes probably gave rise to the modern First Beasts, and the other to the Marsupials and Placentals. Placental mammals, thanks to the appearance of the placenta and true live birth, in the Cenozoic era, pass into a state of biological progress.
The original Order of the Placentals are the Insectivores. From the Insectivores, the Toothless, Rodents, Primates and the now extinct group of Creodonts, primitive predators, separated early. Two branches separated from the Creodonts. One of these branches gave rise to the modern Carnivores, from which the Pinnipeds and Cetaceans separated. Another branch gave rise to the primitive ungulates (Condylartras), and then to the Odd-hoofed, Artiodactyl and related orders.
The final differentiation of modern groups of Mammals was completed in the era of the great glaciations - in the Pleistocene. The modern species composition of mammals is significantly influenced by the anthropogenic factor. In historical time, the aurochs, Steller's cow, tarpan and other species were exterminated.
At the end of the Cenozoic era, part primates a special type of aromorphosis arises - the overdevelopment of the cerebral cortex. As a result, a completely new type of organisms arises - Homo sapiens.
