Facts indicating the unity of all living things. What facts indicate the unity of origin of all living organisms?

1. List the elements that form the basis of living organisms.
1. Unity chemical composition.
2. Openness of living systems.
3. Self-regulation.
4. Variability of living systems.
5. Capacity for growth and development.
6. Ontogenesis.
7. Phylogeny.
8. Irritability.
9. Integrity and discreteness.

2. What substances are classified as inorganic; organic? Using the drawing on p. 33 textbook, make up pie charts content in the cell (in%) of inorganic and organic substances?

Organic substances (proteins, fats, carbohydrates, nucleic acids) And inorganic substances(water, mineral salts).

3. What is the function of water in a living organism?

Water is a solvent, and since everything chemical reactions In living organisms, substances necessary to maintain life occur in solutions, then water is the medium necessary for all these reactions to occur.

4. Describe the importance of mineral salts in the body.

Mineral salts contain everything natural products(fruits, vegetables, meat, bread, eggs, cereals). Vegetables and fruits, fish oil, liver, and meat are rich in vitamins. A person's daily intake of mineral salts should be about 10 grams.
Mineral salts ensure the strength of bones and teeth. They are part of the blood and gastric juice.

5. What is the role of proteins in the body?

Participate in the process of absorption of fats, carbohydrates, minerals and vitamins.
They serve as material for the construction of cells, tissues and organs, the formation of enzymes and most hormones, hemoglobin and other compounds.

6. Name the carbohydrates you know. Which of them are found in plant and which in animal organisms? Describe the significance of these organic substances.

1) Lactose is an essential component of mammals.
2) Sucrose in plants serves as a soluble reserve carbohydrate, as well as a transport form of photosynthesis products, which is easily transported throughout the plant.
3) Glucose is the main source of energy for cells; it is found in the cells of all living organisms.
4) Fructose is present in free form in the vacuoles of plant cells.
5) Starch is synthesized in plant cells and deposited in the form of so-called starch grains.
6) Glycogen (mushrooms, animals and humans) is deposited in muscles and liver cells in the form of tiny granules.
7) Chitin is part of the cuticle of arthropods, the cell walls of many fungi and some protists.

7. Describe the role of fats in the body.

Fats are included in organic compounds - lipids.
Fats in the body are the main storage substance and source of energy.
And also:
Fats form layers between the organs, heart and liver.
The membrane shell contains 30% fat.
Fats bring vitamins A, E and others into the body.
Fats are necessary for the production of many hormones.

8. What organic substances of the cell ensure the storage and transmission of hereditary information? Where are they located in the cage?

Nucleic acids, in particular DNA, are responsible for the storage and transmission of hereditary information
located in chromosomes, in the nucleus.

9. Look at the diagrams on p. 36-37 textbook. How does the chemical composition of living and nonliving bodies differ? Are there elements that are found only in living organisms?

One of the main differences between living bodies and non-living ones is the ability to metabolize
elements that are characteristic of living organisms - biophilic (H, O, C, N)
But both in living and non-living nature, the substances are similar, except that the composition is different; in living organisms, biophilic elements + macro and micro elements predominate.

10. What facts indicate the unity of origin of all living organisms?

The cells of living organisms are uniform in their chemical composition and vital activity; 4 main elements are inherent in all living cells of living organisms: oxygen, nitrogen, hydrogen, carbon.

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Formal statistical tests confirm the origin of all living organisms from a single ancestor

The idea of the unity of origin of all living things is generally accepted among biologists, but the arguments in its favor are mainly qualitative, not quantitative. Formal statistical tests, based on model selection theory and without the a priori assumption that the similarity of protein molecules indicates their relationship, showed that the hypothesis of a single origin for all living things is much more plausible than alternative models, suggesting the independent origin of different groups of organisms from different ancestors.

Darwin thought that all living organisms descended either from one original form or from several (see common descent). Darwin left the question of the number of ancestors open because in the 19th century science did not yet have the means to solve this problem. Today, most biologists are confident that all living things descended from the “last universal common ancestor” (LUCA). This ancestor, however, was unlikely to be a single organism or “species” in the modern sense of the word, but rather represented a polymorphic microbial community in which active horizontal gene exchange took place.

Of course, LUCA was not the first living creature in the world: its appearance was preceded by a long evolution (during which, in particular, the modern genetic code and protein synthesis apparatus were formed, see: Vetsigian, Woese, Goldenfeld. 2006. Collective evolution and the genetic code ). Other creatures most likely lived at the same time as LUCA, but their descendants became extinct. Most experts believe that LUCA already had DNA and RNA, replication and transcription enzymes, ribosomes and other components of the protein synthesis machinery. The strongest argument in favor of the reality of LUCA is the unity of the genetic code and the fundamental similarity of the molecular systems of DNA, RNA and protein synthesis in all living organisms (see: Molecular genetic evidence for evolution). But this argument, for all its persuasiveness, is not quantitative, but qualitative. It is very difficult to estimate its strength numerically.

If life originated once on Earth or in space, then theoretically it could originate several times. In principle, it can be assumed that modern life descended from more than one ancestor. For example, bacteria could have descended from one ancestor, and archaea from another (this point of view is occasionally expressed, although it has few supporters).

Rigorous statistical procedures have so far been largely unused to resolve this dilemma. Standard methods for comparing DNA nucleotide sequences and protein amino acid sequences involve calculating a number of quantitative indicators that reflect the likelihood that the observed similarity is the result of chance (see: The Statistics of Sequence Similarity Scores). Low values of these indicators indicate the statistical significance (non-randomness) of the similarity, but in principle they are not strict evidence of the relationship (single origin) of the molecules being compared. The high similarity of the two sequences can theoretically be explained not only by their common origin, but also by convergent evolution under the influence of similar selection factors.

Even more serious claims can be made against most computer programs designed to build evolutionary trees. These programs, as a rule, are aimed at constructing the “best” evolutionary tree, that is, having maximum statistical support, based on any set of compared sequences. These programs simply do not consider the possibility of multiple unrelated trees growing from multiple independent roots. These methods can quantify and compare the “likelihood” of different trees, but cannot tell whether a model with one tree is more or less plausible than models with two or three independent trees. In other words, the idea of a single common ancestor is “built-in” into these programs from the very beginning (which reflects the deep conviction of biologists in the existence of such an ancestor in any pair of living organisms).

Douglas L. Theobald of Brandeis University (USA) attempted to overcome these limitations and develop independent statistical tests to test the LUCA hypothesis that did not incorporate the idea that sequence similarity is a measure of their relatedness, much less the idea of unity of origin would have been inherent from the very beginning. Theobald did not try to find out how statistically significant the unity of the genetic code of all organisms is. His goal was more specific: he wanted to quantify how reliable (or unreliable) the evidence for LUCA was in the amino acid sequences of key proteins that all living things have.

Theobald's approach is based on tests developed within model selection theories(model selection theory). To compare competing evolutionary models, three tests were used: 1) log likelihood ratio, LLR (see Likelihood-ratiotest; 2) Akaike information criterion (AIC); 3) log Bayes factor. These tests quantify the “likelihood” of the compared models (in this case, evolutionary reconstructions consisting of one or many trees) based on two main criteria: 1) the accuracy of the model’s correspondence to real facts, 2) the parsimonicity (parsimony) of the model. In other words, this technique allows you to select from a variety of models the one that most accurately describes (explains) the observed facts, using a minimum number of assumptions (“free parameters”).

Theobald analyzed the amino acid sequences of 23 proteins that are found in all living organisms (mainly proteins involved in the protein synthesis of aminoacyl-tRNA synthetases, ribosomal proteins, elongation factors, etc.). Protein sequences were taken from 12 organisms: four bacteria, four archaea and four eukaryotes (yeast, Drosophila, worm C. elegans, Human).

The compared evolutionary models were built on the basis of a number of generally accepted assumptions. It was assumed that amino acid sequences could gradually change during evolution by replacing some amino acids with others. Previously developed 20 × 20 matrices were used, reflecting the empirical probability or frequency of substitution of each amino acid for any other. It was also assumed that amino acid substitutions occurring in different evolutionary lines and in different protein regions are not correlated with each other.

The single common ancestor (LUCA) hypothesis has been compared with multiple common ancestor hypotheses, leaving the question of a single or multiple origin of life out of the question. The fact is that the LUCA hypothesis is quite compatible with the multiple origin of life. In this case, either all other ancient life forms, except LUCA, did not leave descendants who have survived to this day, or representatives of several independently arose populations during the course of evolution acquired the ability to exchange genes with each other and actually merged into one species. The models considered by Theobald are compatible with both of these scenarios.

Alternative evolutionary models, the comparison of which is discussed in the article discussed in Nature. a- all living things come from two or more different ancestors, b- from a single ancestor. Dotted lines events of horizontal genetic exchange are indicated. Rice. from the popular synopsis for the Steel & Penny article under discussion

The author considered two classes of models: in the first of them, horizontal genetic exchange was not taken into account, and organisms were supposed to evolve in accordance with tree-like patterns. Models of the second class allowed horizontal exchange (including the symbiogenetic fusion of two organisms into one), so the diagrams were not tree-like, but mesh, with jumpers between the branches. Within each class, the most plausible models built on the basis of various assumptions about the number of original ancestors were compared with each other. The single origin model (ABE, where A is archaea, B is bacteria, E is eukaryote) was compared with a variety of multiple origin models: AE + B (archaea and eukaryotes shared a common ancestor, but bacteria evolved from a different ancestor), AB + E , BE + A, A + B + E, etc. Even the possibility of an independent origin of multicellular animals or humans was considered.

All three tests used strongly supported the LUCA hypothesis in all cases, as opposed to alternative multiple origin hypotheses. For example, for class 1 models, the “plausibility” of the ABE hypothesis turned out to be 10.2860 times higher than that of its closest competitor (model AE + B). This number cannot even be called “astronomical”; in astronomy it is so large numbers No. Hypotheses of class 2 (with horizontal transfer) received approximately the same reliable support when comparing them with hypotheses of class 1. The most plausible model, by a huge margin from all others, was the LUCA model of class 2: with a single common ancestor and a network structure due to horizontal genetic exchange between evolving lines. This model, in particular, adequately reflects the symbiogenetic origin of eukaryotes: some of the 23 examined proteins of eukaryotes were clearly inherited from bacteria, while others were inherited from archaea.

Thus, the amino acid sequences of key proteins found in every living cell provide strong statistical support for the LUCA hypothesis. At the same time, the main evidence in favor of the unity of origin is not the magnitude of the similarity as such (the actual similarity of homologous proteins in humans, yeast and bacteria is actually not that great), but character(or structure) of this similarity, that is, the distribution of identical or similar amino acids in properties throughout the protein molecule in different organisms. The structure of the observed similarity is such that it allows some proteins to be “derivable” from others, and so the single origin hypothesis explains the whole picture much better than other models. In the supplementary materials (PDF, 352 KB) to the article discussed, Douglas Theobald gives fictional examples of protein molecules that have very high similarity, but for which a single origin turns out to be less likely than multiple. For example, this happens if protein A is similar to protein B in some amino acid positions, and with protein C in others. For real proteins, the LUCA hypothesis explains the observed similarities in the most parsimonious way.

If we include proteins that not all but only some organisms have (for example, only eukaryotes), the results remain the same, because new types of proteins must have arisen in different evolutionary lines one way or another - regardless of whether these lines had the same or different origins.

This work, of course, is not a final solution to the problem; rather, it should be considered as a first step. It is quite difficult to completely exclude all possible alternative interpretations of the results obtained. This will require more detailed knowledge of the patterns of protein evolution and even more complex statistical methods.

Sources:
1) Douglas L. Theobald. A formal test of the theory of universal common ancestry // Nature. 2010. V. 465. P. 219-222.
2) Mike Steel, David Penny. Common ancestry put to the test // Nature. 2010. V. 465. P. 168-169.

Today, science has many facts confirming the reality of evolutionary processes. What is the most important evidence for evolution? Embryological, biochemical, anatomical, biogeographical and other evidence are discussed in this article.

Unity of origin of the living world

This is difficult to verify, but all living organisms (bacteria, fungi, plants, animals) have almost the same chemical composition. Nucleic acids and proteins play an important role in the body of every representative of the living world. In this case, there is similarity not only in the structure, but also in the functioning of cells and tissues. Evidence of evolution (embryological, biogeographical, anatomical examples can be found in this article) is important topic, which everyone should navigate.

It is worth considering that almost all living beings on Earth consist of cells, which are considered small “bricks” great life. Moreover, their functions and structure are very similar, regardless of the type of organism.

Embryological Evidence for Evolution: Briefly

There is some embryological evidence to support the theory of evolution. Many of them were discovered back in the nineteenth century. Modern scientists not only did not reject them, but also supported them with many other factors.

Embryology is the science that deals with the study of organisms. It is known that every multicellular animal develops from an egg. And it is the similarity in the initial stages of embryo development that is evidence of their common origin.

Karl Baer's proof

This famous scientist, who conducted many experiments, was able to notice that all chordates are completely similar at the initial stage of development. For example, first the notochord develops in embryos, then the neural tube and gills. It is the complete similarity of the embryos at the initial stage that speaks of the unity of origin of all chordates.

Already during the later stages, distinctive features become noticeable. Scientist Karl Baer was able to notice that in the first stages of the embryonic fetus, only signs of the type to which the organism belongs can be determined. Only later do features characteristic of the class, order and, finally, species appear.

Haeckel-Muller proof

Embryological evidence of evolution includes the Haeckel-Müller law, which shows the connection between individual and historical development. Scientists considered the fact that every multicellular animal, when developing, passes through the stage of a single cell, that is, a zygote. For example, in every multicellular organism, at the initial stages of development, a notochord appears, which is subsequently replaced by a spine. However, the ancestors of modern animals did not have this part of the musculoskeletal system.

Embryological evidence of evolution also includes the development of gill slits in mammals and birds. This fact confirms the origin of the latter from ancestors from the Pisces class.

The Haeckel-Müller law states: every multicellular animal, during its individual embryonic development, goes through all stages of phylogenesis (historical, evolutionary development).

Anatomical evidence of evolution

There are three main anatomical evidence for evolution. This may include:

The presence of characteristics that were present in the ancestors of animals. For example, some whales can develop hind limbs, and some horses can develop small hooves. Such signs can also appear in humans. For example, there are cases of a child being born with a ponytail, or thick hair on the body. Such atavisms can be considered evidence of connections with more ancient organisms.
The presence of transitional forms of organisms in the plant and animal world. It is worth considering green euglena. She simultaneously has the characteristics of both an animal and a plant. The presence of so-called transitional forms confirms the evolutionary theory.
Rudiments are underdeveloped organs or parts of the body that today are not important for living organisms. Such structures begin to form in the embryonic period, but over time their genesis ceases and they remain underdeveloped. Anatomical examples of evidence for evolution can be seen by studying, for example, whales or birds. The first individual has a pelvic girdle, and the second has unnecessary fibula bones. The presence of rudimentary eyes in blind animals is also considered a very striking example.

Biogeographical arguments

Before considering this evidence, we need to understand what biogeography studies. This science studies the patterns of distribution of living organisms on planet Earth. The first biographical information began to appear in the eighteenth century AD.

Biogeographic evidence for evolution can be studied by viewing a zoogeographic map. Scientists have identified six main areas with a significant diversity of representatives living on them.

Despite the differences in flora and fauna, representatives of zoogeographical regions still have many similar characteristics. Or vice versa, the further continents are from each other, the more their inhabitants differ from each other. For example, on the territory of Eurasia and North America one can notice a significant similarity of fauna, because these continents separated from each other not so long ago. But Australia, which separated from other continents many millions of years earlier, is characterized by a very peculiar animal world.

Features of flora and fauna on the islands

Biogeographic evidence for evolution is also worth studying by looking at individual islands. For example, living organisms on islands that have only recently separated from continents are not very different from the animal world on the continents themselves. But the ancient islands, located at a great distance from the continents, have many differences in the animal and plant world.

Evidence from paleontology

Paleontology is a science that studies the remains of already extinct organisms. Scientists with knowledge in this area can confidently say that organisms of the past and present have both many similarities and differences. This is also proof of evolution. We have already considered embryological, biogeographical, anatomical and paleontological arguments.

Phylogenetic information

Such information is an excellent example and confirmation of the evolutionary process, as it allows us to understand the peculiarities of the development of organisms of individual groups.

For example, the famous scientist V.O. Kovalevsky was able to demonstrate the course of evolution using horses as an example. He proved that these one-toed animals descended from five-toed ancestors who inhabited our planet about seventy million years ago. These animals were omnivores and lived in the forest. However, climate changes have led to a sharp decrease in forest area and an expansion of the steppe zone. In order to adapt to new conditions, these animals had to learn to survive in them. The need to find good pastures and protection from predators became the reason for evolution. Over many generations, this led to changes in the limbs. The number of phalanges of the fingers decreased from five to one. The structure of the whole organism also became different.

Evidence of evolution (embryological, biogeographical and other examples we analyzed in this article) can be considered using the example of already extinct species. Naturally, the theory of evolution is still being developed. Scientists from all over the world are trying to find more information about the development and changes of living organisms.

Modern science has many facts that prove the existence of the evolutionary process. This is data from biochemistry, genetics, embryology, anatomy, systematics, biogeography, paleontology and many other disciplines.

Evidence of the unity of origin of the organic world. All organisms, be they viruses, bacteria, plants, animals or fungi, have remarkably similar elementary chemical compositions. In all of them, proteins and nucleic acids, which are built according to a single principle and from similar components, play a particularly important role in life phenomena. It is especially important to emphasize that a high degree of similarity is found not only in the structure of biological molecules, but also in the way they function. The principles of genetic coding, biosynthesis of proteins and nucleic acids (see § 14-16) are the same for all living things. The vast majority of organisms use ATP as energy storage molecules; the mechanisms for breaking down sugars and the basic energy cycle of the cell are also the same.

Most organisms have a cellular structure. The cell is the basic “building block” of life. Its structure and functioning are very similar in different organisms. Cell division - mitosis, and in germ cells - meiosis - is carried out in fundamentally the same way in all eukaryotes.

It is extremely unlikely that such amazing similarities in the structure and functioning of living organisms were the result of a random coincidence. It is the result of their common origin.

Embryological evidence for evolution. Embryological data speak in favor of the evolutionary origin of the organic world.

Russian scientist Karl Baer (1792-1876) discovered striking similarities between the embryos of various vertebrates. He wrote: “The embryos of mammals, birds, lizards and snakes are extremely similar to each other in the earliest stages, both in general and in the method of development of individual parts. I have two small embryos preserved in alcohol, which I forgot to label, and now I am completely unable to say to which class they belong. Maybe these are lizards, maybe they are small birds, and maybe they are very small mammals, so great is the similarity in the structure of the head and body of these animals. However, these embryos do not yet have limbs. But even if they were in the earliest stages of their development, even then we would not know anything, because the legs of lizards and mammals, the wings and legs of birds, and the arms and legs of man develop from the same basic form." .

Rice. 52. Similarity of the initial stages of embryonic development of vertebrates

At later stages of development, differences between embryos increase, and signs of a class, order, and family appear (Fig. 52). Charles Darwin considered the similarity of the early stages of ontogenesis in different representatives of large taxa as an indication of their origin through evolution from common ancestors. Modern discoveries in the field of developmental genetics have confirmed Darwin's hypothesis. It has been shown, for example, that the most important processes of early ontogenesis in all vertebrates are controlled by the same genes. Moreover, many of these regulatory genes are also found in invertebrates (worms, mollusks and arthropods). Figure 53 shows the regions of activity of Hox family genes during the formation of the nervous system in Drosophila and mice. The last common ancestor of these two animal species existed more than 500 million years ago. Despite this, in the mouse and in Drosophila, not only the regulatory genes themselves have remained largely unchanged, but also the order of their arrangement in chromosomes, the sequence of their inclusion in ontogenesis, and the relative position of the regions of the developing nervous system in which these genes are active.

Rice. 53. Comparison of regions of activity of genes that control the development of the nervous system in Drosophila and mice

Morphological evidence of evolution. Of particular value for proving the unity of the origin of the organic world are forms that combine the characteristics of several large systematic units. The existence of such intermediate forms indicates that in previous geological eras there lived organisms that were the ancestors of several systematic groups. A clear example This can be done by the single-celled organism Euglena verida. It simultaneously has characteristics typical of plants (chloroplasts, the ability to use carbon dioxide) and of protozoa (flagella, a light-sensitive eye, and even a semblance of a mouth opening).

Lamarck also introduced the division of animals into vertebrates and invertebrates. For a long time no connecting links were discovered between them until the research of the domestic scientist A. O. Kovalevsky established a connection between these groups of animals. A. O. Kovalevsky proved that a typical invertebrate at first glance - the sessile ascidian - develops from a free-swimming larva. It has a notochord and is very similar to the lancelet, a representative of what was then believed to be a vertebrate. Based on such studies, the entire group of animals, to which ascidians belonged, was added to the vertebrates and this type was given the name chordates.

Communication between different classes animals also well illustrates the commonality of their origin. Oviparous animals (for example, the echidna and the platypus) are intermediate between reptiles and mammals in a number of features of their organization.

The structure of the forelimbs of some vertebrates (Fig. 54), for example, the flippers of a whale, a dolphin, a mole’s paw, a wing bat, the paws of a crocodile, the wings of a bird, the hands of a person, despite the performance of completely different functions by these organs, they are fundamentally similar. Some bones in the skeleton of the limbs may be absent, others may be fused, the relative sizes of the bones may change, but their homology, i.e., similarity based on common origin, is completely obvious. Homologous are those organs that develop from the same embryonic rudiments in a similar way.

Rice. 54. Homology of the forelimbs of vertebrates

Some organs or their parts do not function in adult animals and are superfluous for them - these are the so-called vestigial organs, or rudiments. The presence of rudiments, as well as homologous organs, is also evidence of a common origin. Vestigial eyes are found in completely blind animals that lead an underground lifestyle. The skeleton of the whale's hind limbs, hidden inside the body, is a rudiment indicating the land-based origin of its ancestors. Humans also have vestigial organs. These are the muscles that move the auricle, the rudiment of the third eyelid, or the so-called nictitating membrane, etc.

Paleontological evidence of evolution. The development of chordates, for example, was carried out in stages. First, the lower chordates arose, then fish, amphibians, and reptiles appeared successively over time. Reptiles, in turn, give rise to mammals and birds. At the dawn of their evolutionary development, mammals were represented by a small number of species, while reptiles flourished. Later, the number of species of mammals and birds sharply increases and most species of reptiles disappear. Thus, paleontological data indicate a change in the forms of animals and plants over time.

In some cases, paleontology indicates the causes of evolutionary transformations. The evolution of horses is interesting in this regard. Modern horses descended from small omnivorous ancestors who lived 60-70 million years ago in forests and had a five-toed limb. Climate change on Earth, which resulted in a reduction in forest areas and an increase in the size of steppes, led to the fact that the ancestors of modern horses began to develop a new habitat - the steppes. The need for protection from predators and movement over long distances in search of good pastures led to the transformation of the limbs - a reduction in the number of phalanges down to one (Fig. 55). In parallel with the change in the limbs, a transformation of the entire organism took place: an increase in body size, a change in the shape of the skull and a complication of the structure of the teeth, the emergence of features characteristic of herbivorous mammals. digestive tract and much more.

Rice. 55. Historical series of changes in the structure of the forelimb of the horse

As a result of the change external conditions under the influence of natural selection, there was a gradual transformation of small five-toed omnivores into large herbivores. The richest paleontological material is one of the most convincing evidence of the evolutionary process that has been going on on our planet for more than 3 billion years.

Biogeographic evidence for evolution. A clear indication of the evolutionary changes that have occurred and are ongoing is the distribution of animals and plants across the surface of our planet. Back in the era of the Great geographical discoveries travelers and naturalists were amazed by the diversity of animals in distant countries and the peculiarities of their distribution. However, only A. Wallace managed to bring all the information into a system and identify six biogeographic regions (Fig. 56): 1) Paleoarctic, 2) Neoarctic (Palaeoarctic and Neoarctic zones are often combined into the Holarctic region), 3) Indo-Malayan, 4) Ethiopian , 5) Neotropical and 6) Australian.

Rice. 56. Map of biogeographic zones

Comparison of the animal and plant world of different zones provides rich scientific material to prove the evolutionary process. The fauna and flora of the Paleoarctic (Eurasian) and Neoarctic (North American) regions, for example, have much in common. This is explained by the fact that in the past there was a land bridge between these areas - the Bering Isthmus. The Neoarctic and Neotropical regions, on the contrary, have little common features, although currently connected by the Isthmus of Panama. This is explained by the isolation of South America for several tens of millions of years. After the Panama Bridge, only a few South American species managed to penetrate north (porcupine, armadillo, opossum). North American species have been somewhat more successful in colonizing the South American region. Llamas, deer, foxes, otters, and bears entered South America, but did not have a significant impact on its unique species composition.

Interesting and original fauna Australian region. It is known that Australia separated from South Asia even before the emergence of higher mammals.

Thus, the distribution of animal and plant species on the surface of the planet and their grouping into biogeographic zones reflect the process of the historical development of the Earth and the evolution of living things.

Island fauna and flora. To understand the evolutionary process, the fauna and flora of the islands are of interest. The composition of their fauna and flora depends entirely on the history of the origin of the islands. Islands can be of continental origin, that is, they can be the result of the separation of a part of the mainland, or of oceanic origin (volcanic and coral).

Mainland islands are characterized by fauna and flora similar in composition to the mainland. However, the older the island and the more significant the water barrier, the more differences are found. The British Isles separated from Europe only recently and have a fauna identical to that of Europe. On long-separated islands, the process of divergence of species goes much further. In Madagascar, for example, there are no large ungulates typical of Africa: bulls, antelopes, rhinoceroses, zebras. No and large predators(lions, leopards, hyenas), great apes(baboons, monkeys). However, many lower primates- lemurs that are not found anywhere else.

A completely different picture is revealed when examining the faunas of oceanic islands. Their species composition is very poor. Most of these islands lack terrestrial mammals and amphibians, unable to overcome significant distances. water obstacles. The entire fauna of oceanic islands is the result of the accidental introduction of certain species, usually birds, reptiles, and insects. Representatives of such species that find their way to oceanic islands receive ample opportunities for reproduction. For example, on the Galapagos Islands, out of 108 bird species, 82 are endemic (that is, not found anywhere else) and all 8 reptile species are characteristic only of these islands. On Hawaiian Islands A wide variety of snails has been discovered, of which 300 endemic species belong to a single genus.

A huge number of diverse biogeographical facts indicate that the characteristics of the distribution of living beings on the planet are closely related to the transformation earth's crust and with evolutionary changes species.

Molecular evidence of evolution. At present, the complete deciphering of the human genome (the totality of all genes) and the genomes of a number of animals, plants and microorganisms has been almost completed. The complete sequence of nucleotides in DNA is known huge number types of living organisms. Comparing these sequences provides new clues to the lineage of life on Earth.

Many mutations are substitutions of one nucleotide for another. Mutations usually occur during DNA replication (see § 14). It follows that the more generations that have passed since the divergence of two species from a common ancestor, the more random nucleotide substitutions should have accumulated in the genomes of these daughter species. The common ancestor of humans and chimpanzees existed about five million years ago, and the common ancestor of humans and mice existed more than 80 million years ago. When we compare the nucleotide sequences of genes, such as the beta-globin gene, we see that there is much less difference between the genes of humans and chimpanzees than between the genes of humans (or chimpanzees) and mice.

Quantifying these differences allows us to construct family tree, showing the relationship of various taxa (species, orders, families, classes), and determine the relative time of their divergence. Basically, this tree coincides with those that were built on the basis of morphological, embryological and paleontological data. However, in some cases, surprising things are discovered. It turned out that whales and artiodactyls are much closer relatives than artiodactyls and equids. The African golden mole is phylogenetically closer to the elephant than to our moles. Modern methods molecular genetics make it possible to analyze the genes of not only living organisms, but also long-extinct species, using traces of DNA in fossil remains. This helps to trace the evolutionary paths of life on Earth.

0 as evidenced by the following facts: similar organization molecular processes in all organisms living on Earth; the presence of intermediate forms and rudimentary organs? Justify your answer.
The flora and fauna of North America and Eurasia are similar, but the flora and fauna of North and South America are very different. How do you explain these facts?
Typically, endemic species (not found anywhere else on the globe) are quite common on the islands. How can this be explained?
The fossil animal, Archeopteryx, had the characteristics of a bird and a reptile. Assess this fact from a scientific point of view.

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Attention! Slide previews are for informational purposes only and may not represent all the features of the presentation. If you are interested this work, please download the full version.

Lesson format: frontal, individual.

Teaching methods: heuristic method, explanatory and illustrative, practical, visual.

Equipment: Presentation “Basic Evidence of Evolution”, computer, multimedia projector, collections “Shapes of fossil species of plants and animals”.

The purpose of the lesson: to form and reveal the essence of the main evidence of evolution.

Lesson objectives:

identify the main evidence for the development of the organic world;
evaluate the biogenetic law of F. Muller and E. Haeckel as embryological evidence;
find out the significance for science of fossil transitional forms as paleontological evidence, study comparative anatomical (morphological), biogeographical evidence of evolution.
continue skills development independent work with text, with handouts, with presentation.

Lesson progress

I. Testing knowledge.

Frontal conversation on key issues on the topic “Evolution”.

Define the concept of evolution.
Name the periods of development of evolution.
Define creationism. What is the essence of a metaphysical worldview?
Tell us about the main views and mistakes of C. Linnaeus, determine the role of his works in the development of biology.
Tell us about the main views and mistakes of J.B. Lamarck, determine the role of his works in the development of biology.
What prerequisites for the emergence of Darwinism do you know?
Tell us about the main stages of life of the great English naturalist Charles Darwin.
What are the main provisions of Charles Darwin's theory of evolution?
Explain from the point of view of K. Linnaeus, J-B. Lamarck, C. Darwin education long neck in the giraffe and the absence of visual organs in the mole rat.

II. Learning new material (lesson topic on slide 1).

Presentation – “Basic Evidence for Evolution.”

The fact of evolution, that is, the historical development of living organisms from simple forms to more highly organized ones, which is based on the processes of the unique functioning of genetic information, was accepted and confirmed by the data of biochemistry, paleontology, genetics, embryology, anatomy, systematics and many other sciences that had facts , proving the existence of an evolutionary process.

The main evidence for evolution includes (slide 2):

1. Similar chemical composition of the cells of all living organisms.

2. General plan of the structure of cells of all living organisms.

3. The universality of the genetic code.

4. Unified principles of storage, implementation and transfer of genetic information.

5. Embryonic evidence of evolution.

6. Morphological evidence of evolution.

7. Paleontological evidence of evolution.

8. Biogeographical evidence of evolution.

(Front conversation with identification of the main provisions of the evidence)

What is the chemical composition of organisms? (Similar elemental chemical composition of the cells of all organisms) (slide 3);

What is the elementary unit of structure of all living organisms? (A cell is an elementary unit of living things; its structure and functioning are very similar in all organisms) (Slide 4);

What does the universality of the genetic code mean? (Proteins and nucleic acids are always built according to a single principle and from similar components; they play a particularly important role in the life processes of all organisms) (slide 5);

The principles of genetic coding, biosynthesis of proteins and nucleic acids are common to all living things. (slide 6) .

Embryological evidence

The fact of the unity of origin of living organisms was established on the basis of embryological studies, which are based on data from the science of embryology.

Embryology (from the Greek embryo - embryo and logos - teaching) is a science that studies the embryonic development of organisms. All multicellular animals develop from a single fertilized egg. In the process of individual development, they go through the stages of fragmentation, the formation of two- and three-layer embryos, and the formation of organs from germ layers. The similarity of the embryonic development of animals indicates the unity of their origin.

Embryology, depending on the objectives, is divided into: general, comparative, experimental, population and ecological.

Embryological data that provides evidence of evolution include :

1. Karl Baer's law of germline similarity (slides 7, 8) , which reads: "Embryos show, even from the earliest stages, a certain general resemblance within the type" . In all chordates, in the early stages of development, the notochord is formed, the neural tube appears, gills are formed in the anterior part of the pharynx, etc. The similarity of the embryos indicates the common origin of these organisms. As the embryos develop, their differences become more and more obvious. K. Baer was the first to discover that during embryonic development, general signs type, then successively class, order and, finally, species.

The divergence of characteristics of embryos during development is called embryonic divergence, and it is explained by the history of a given species.

2.Biogenetic Haeckel-Müller law (slides 7, 9) , indicating the connection between individual (ontogenesis) and historical (phylogeny) development. This law was formulated in 1864-1866. German scientists F. Muller and E. Haeckel. In their development, multicellular organisms pass through a unicellular stage (zygote stage), which can be considered as a repetition of the phylogenetic stage of the primitive amoeba. In all vertebrates, a notochord is formed, which is then replaced by a spine, but in their ancestors the notochord remained throughout their lives. During the embryonic development of birds and mammals, gill slits appear in the pharynx. This fact can be explained by the origin of these land animals from fish-like ancestors. These and other facts led Haeckel and Muller to the formulation of the biogenetic law. It reads: “Ontogenesis is a short and rapid repetition of phylogeny; each organism in its individual development repeats the stages of development of its ancestors.” Figuratively speaking, every animal during its development climbs its own family tree. However, ontogeny does not exactly repeat phylogeny. Therefore, the repetition of the stages of the historical development of a species in embryonic development occurs in a compressed form, with the loss of a number of stages. In addition, embryos resemble not the adult forms of their ancestors, but their embryos.

Morphological evidence

Evidence for the evolution of this group includes:

1) Comparative anatomical studies have shown the presence in modern flora and fauna transitional forms of organisms (slide 10) , combining the characteristics of several large systematic units. For example, green euglena combines the characteristics of a plant (chloroplasts, photosynthesis) and animals (flagella, light-sensitive eye, similarity oral apparatus); The echidna and platypus stand between reptiles and mammals (they lay eggs and feed their young with milk). The existence of such intermediate forms indicates that in previous geological eras there lived organisms that were the ancestors of several systematic groups.

2) Availability within a class, type homologous organs (slide 11) , formations similar to each other in their general structural plan, position in the body and appearance in the process of ontogenesis. Homology is associated with the presence in different species of identically acting hereditary factors (so-called homologous genes) inherited from a common ancestor. For example, the flippers of a whale, the paws of a mole, a crocodile, the wings of a bird, a bat, and human hands, despite performing completely different functions, are fundamentally similar in structure. Homologous organs are the result of divergence - the divergence of characteristics within a population of a species that occurs under the influence of natural selection. A general pattern of evolution leading to the formation of new species, genera, classes, etc.

3) Availability rudiments(from Latin rudimentum - rudiment, fundamental principle) (slide 12, 13) - relatively simplified, underdeveloped, in comparison with the homologous structures of ancestors, organs that have lost their main significance in the body during evolutionary development (Slide 11-13). Rudiments are laid down during the embryonic development of the organism, but do not fully develop. They are found in all individuals of a given species. For example, the fibula in birds, the pelvic girdle in a whale, the eyes in burrowing animals, etc.; The presence of rudiments, as well as homologous organs, indicates a common origin of living forms. The whale's hind limbs, hidden inside the body, are a vestige that proves the terrestrial origin of its ancestors. In humans, rudimentary organs are also known: the muscles that move the auricle, the rudiment of the third eyelid, etc. In some organisms, vestigial organs can develop into normal-sized organs. Such a return to the organ structure of ancestral forms is called atavism.

4) Availability atavisms(from Latin atavus - ancestor) (slide 14) , characteristics appearing in individual individuals of a given species that existed in distant ancestors, but were lost in the process of evolution. For example, hind limbs occasionally appear in whales; among thousands of one-toed horses, individuals are occasionally found that have developed small hooves of the second and fourth fingers. There are known cases of the appearance of atavistic signs in humans: the birth of children with primary hair, with a long ponytail, etc. The occurrence of atavisms indicates the possible structure of a particular organ in ancestral forms. Atavisms are a manifestation of evolutionary memory of ancestors. The reasons for their appearance are that the genes responsible for this trait are preserved in the evolution of a given species, but their action during normal development is blocked by repressor genes. After many generations in the ontogenesis of individual individuals, for certain reasons, the blocking is removed and the trait appears again.

Paleontological evidence

Paleontological evidence is based on the science of paleontology.

Paleontology (from the Greek paleo - ancient; ontos - being; logos - teaching) is a science that studies the remains of extinct organisms, identifying their similarities and differences with modern organisms. Founders of paleontology: J. Cuvier, J.-B. Lamarck, A. Brongniart. The term "paleontology" was proposed in 1822 by A. Blainville. The foundations of modern evolutionary paleontology were laid by V.O. Kovalevsky.

Paleontology solves the following problems:

study of the flora and fauna of the past, because fossil remains provide a lot of material about the successive connections between various systematic groups;
identification of the early stages of the evolution of life and events at the boundaries of the main divisions of the history of the Earth;
identifying the isolation of the trunks of the organic world;
identification of the main stages of development of the organic world; By comparing the fossil remains of the earth's layers from different geological eras, they conclude that the organic world has changed over time.

Paleontology provides the following evidence in favor of evolution:

1) Information about phylogenetic (evolutionary) series (slide 15), which not only are an excellent illustration of evolution, but also allow us to find out the reason for the evolution of certain groups of organisms. Works by V.O. Kovalevsky were the first paleontological studies that were able to show that some species descend from others. Studying the history of the development of horses, V.O. Kovalevsky showed that modern one-toed animals descend from small five-toed omnivorous ancestors who lived 60-70 million years ago in forests. Climate change on Earth, which resulted in a reduction in forest areas and an increase in the size of steppes, led to the fact that the ancestors of modern horses began to develop a new habitat - the steppes. The need for protection from predators and movement over long distances in search of good pastures led to the transformation of the limbs - a reduction in the number of phalanges down to one. In parallel with the change in the limbs, a transformation of the entire organism took place: an increase in body size, a change in the shape of the skull and a more complex structure of the teeth, the emergence of a digestive tract characteristic of herbivorous mammals, and much more.

2) Information about fossil transitional forms (the definition of transitional forms was given above), which have not survived to the present day and are present only in the form of fossil remains. The existence of transitional forms between various types and classes shows that the gradual nature of historical development is characteristic not only of lower systematic categories (species, genera, families), but also of higher categories and that they are also a natural result of evolutionary development. Examples of fossil transitional forms are: ancient lobe-finned fish, connecting fish with four-legged amphibians that came to land; seed ferns - a transitional group between ferns and gymnosperms, psilophytes, wild-toothed lizard, Archeopteryx, etc. (Slides 16, 17).

Biogeographical evidence

Biogeography (from the Greek bio - life, geo - earth, graph - writing) - the science of patterns of distribution across to the globe communities of living organisms and their components - species, genera and other taxa. Biogeography includes zoogeography and botanical geography. The main sections of biogeography began to take shape at the end of the 18th and in the 1st half of the 19th centuries, thanks to numerous expeditions. At the origins of biogeography were A. Humboldt, A.R. Wallace, F. Sclater, P.S. Pallas, I.G. Borschov et al.

Biogeographic data that is evidence of evolution includes the following:

1. Features of the distribution of animals and plants across different continents (slides 18, 19) , as clear evidence of the evolutionary process. A.R. Wallace, one of the outstanding predecessors of Charles Darwin, brought all the information about the distribution of animals and plants into the system and identified six zoogeographical regions (students’ work with a map of zoogeographical regions of the world):

1) Paleoarctic (Europe, North Africa, North and Central Asia, Japan);

2) Neoarctic ( North America);

3) Ethiopian (Sub-Saharan Africa);

4) Indomalayan ( South Asia, Malay Archipelago);

5) Neotropical (South and Central America);

6) Australian (Australia, New Guinea, New Zealand, New Caledonia).

The degree of similarity and difference of floras and faunas between different biogeographical regions varies. Thus, the paleoarctic and neoarctic regions, despite the lack of land connections between them, show significant similarities in floras and faunas. The fauna and flora of the neo-arctic and neotropical regions, although there is a land-based Isthmus of Panama between them, are very different from each other. How can this be explained? This can be explained by the fact that Eurasia and North America were once part of the single continent of Laurasia and their organic world developed together. Land connection between Northern and South America, on the contrary, arose relatively recently, and their flora and fauna developed separately for a long time. The organic world of Australia stands apart, as it separated from South Asia more than 100 million years ago, and only during the Ice Age did a few placentals - mice and dogs - move here through the Sunda Archipelago. Thus, the closer the connection of the continents, the more related forms live there; the more ancient the isolation of parts of the world from each other, the greater the differences between their populations.

2. Features of the fauna and flora of the islands also testify in favor of evolution. The organic world of the mainland islands is close to the mainland if the separation of the island occurred recently (Sakhalin, Britain). The older the island and the more significant the water barrier, the greater the differences in organic world this island and the nearby mainland (Madagascar). The organic world of the volcanic and coral islands is poor and is the result of the accidental introduction of some species capable of moving through the air.

Mainland Islands

The living world is close to the mainland. British, Sakhalin The islands separated from the land several thousand years ago, so the living world is very similar to the mainland. The older the island and the more significant the water barrier, the more differences are found.

Madagascar (slide 20). There are no large ungulates typical of Africa: bulls, antelopes, zebras. There are no large predators: lions, leopards, hyenas, great apes. But this island is the last refuge of lemurs. Once upon a time, before the advent of monkeys, lemurs were the dominant primates. But they could not compete with their more advanced relatives and disappeared everywhere except Madagascar, which separated from the mainland before apes evolved. Madagascar has 46 genera of birds found nowhere else in the world. Chameleons– larger and more diverse than in Africa. Unlike Africa, there are no poisonous snakes. But there are many pythons and non-venomous snakes. According to the history of the living world, snakes appeared quite late compared to other reptiles, and poisonous snakes are the youngest of them. Madagascar separated from the continent before snakes appeared there. There are about 150 species of frogs in Madagascar.

Oceanic islands

The species composition of the fauna of oceanic islands is poor and is the result of the accidental introduction of some species, usually birds, reptiles, and insects. Land mammals, amphibians and other animals are not able to overcome significant water barriers; they are absent on most of these islands. Galapogos Islands (slide 21) – 700 km away from the coast of South America. Only well-flying forms can overcome this distance. 15% of bird species are represented by South American species, and 85% are different from mainland species and are not found anywhere else.

III. Consolidation of knowledge.

1. List all the evidence for evolution.

2. Do a test job.

Test “Evidence of Evolution”

1. What evidence of evolution is based on paleontological data?