Significant evolutionary progressive acquisitions of birds are. Bird homework test. I. Organizational moment

The evolution of the organic world is a long and complex process that takes place at different levels of organization of living matter and flows in different directions. The development of living nature occurred from lower forms with a relatively simple structure to increasingly complex forms. At the same time, within certain groups of organisms, special devices (adaptations) developed, allowing them to exist in specific habitats. For example, many aquatic animals have membranes between their toes that make swimming easier (newts, frogs, ducks, geese, platypus, etc.).

Analyzing the historical development of the organic world and numerous specific adaptations, the largest Russian evolutionists A. N. Severtsov and I. I. Shmalgauzen identified three main directions of evolution: aromorphosis, ideological adaptation and degeneration.

Aromorphosis (or arogenesis) is called major evolutionary changes leading to a general complication of the structure and functions of organisms and allowing the latter to occupy fundamentally new habitats or significantly increasing the competitive ability of organisms in existing habitats. Aromorphoses make it possible to move into new habitats (that is, enter new adaptation zones). Therefore, aromorphoses are relatively rare phenomena in the living world and are of a fundamental nature, having a great influence on the further evolution of organisms.

An adaptation level or adaptive zone is a certain type of habitat with its characteristic environmental conditions or a complex of certain adaptations characteristic of a particular group of organisms ( general conditions life or similar methods of assimilation of some vital resources). For example, the adaptive zone of birds is the development of air space, which provides them with protection from many predators, new ways of hunting for flying insects (where they have no competitors), rapid movement in space, the ability to overcome large obstacles inaccessible to other animals (rivers, seas, mountains, etc.), the ability for long-distance migrations (flights), etc. Therefore, flight is a major evolutionary acquisition (aromorphosis).

The most striking examples of aromorphoses are multicellularity and the emergence of a sexual method of reproduction. Multicellularity contributed to the emergence and specialization of tissues and led to the complication of the morphology and anatomy of many groups of organisms, both plants and animals. Sexual reproduction has significantly expanded the adaptive abilities of organisms (combinative variability).

Aromorphoses provided animals with more effective ways nutrition and increased the efficiency of metabolism - for example, the appearance of jaws in animals made it possible to switch from passive to active nutrition; the liberation of the digestive canal from the skin-muscular sac and the appearance of an excretory opening in it fundamentally improved the efficiency of food absorption due to the specialization of its different sections (the appearance of the stomach, sections of the intestine, digestive glands, the rapid removal of unnecessary products). This significantly increased the survival capabilities of organisms even in places with low nutritional resources.

The largest aromorphosis in the evolution of animals was warm-bloodedness, which sharply activated the intensity and efficiency of metabolism in organisms and increased their survival in habitats with low or sharply changing temperatures.

As examples of aromorphoses in the animal world, one can also recall the formation of the internal cavity of organisms (primary and secondary), the appearance of the skeleton (internal or external), the development of the nervous system and especially the complication of the structure and functions of the brain (the appearance of complex reflexes, learning, thinking, second signal systems in humans, etc.) and many other examples.

In plants, major aromorphoses are: the appearance of a conducting system that connects different parts of the plant into a single whole; the formation of a shoot - a vital organ that provides plants with all aspects of life and reproduction; the formation of a seed - an organ of reproduction that arises sexually, the development and maturation of which is ensured by the resources of the entire maternal organism (tree, shrub or other life form of plants) and which has an embryo well protected by the tissues of the seed (gymnosperms and angiosperms); the appearance of a flower that increased the efficiency of pollination, reduced the dependence of pollination and fertilization on and provided protection for the egg.

In bacteria, aromorphosis can be considered the emergence of an autotrophic mode of nutrition (phototrophic and lithotrophic or chemosynthetic), which allowed them to occupy a new adaptation zone - habitats completely devoid of organic food sources or having a deficiency of them. In bacteria and fungi, aromorphoses include the ability to form certain biologically active compounds (antibiotics, toxins, growth substances, etc.), which significantly increase their competitive ability.

Arogenesis can also occur at the interspecific (or biocenotic) level during the interaction of organisms of different systematic positions. For example, the appearance of cross-pollination and the attraction of insects and birds for this can be considered as aromorphosis. Large biocenotic aromorphoses are: the formation of mycorrhizae (symbiosis of fungi and plant roots) and lichens (combination of fungi and algae). These types of associations allowed the symbionts to live in places where they would never have settled separately (on poor soils, on rocks, etc.). Particularly significant is the union of fungi and algae, which led to the emergence of a new symbiotic life form - lichens, which are morphologically very similar to a single organism resembling plants. The largest aromorphosis of this type is the eukaryotic cell, consisting of different organisms (prokaryotes) that have completely lost their individuality and turned into organelles. The eukaryotic cell has a more active and economical metabolism compared to the prokaryotic cell and ensured the emergence and evolution of the kingdoms of fungi, plants and animals.

Aromorphoses are major events in the evolution of the organic world, and they persist in populations and in further development lead to the emergence of new large groups of organisms and taxa of high rank - orders (orders), classes, types (divisions).

It is assumed that aromorphosis is most likely in initially primitive or less specialized forms of organisms, since they tolerate environmental changes more easily and it is easier for them to adapt to new habitats. Specialized forms adapted to certain, often quite narrowly limited, living conditions usually die when such conditions change abruptly. That is why in nature, along with highly organized and specialized forms of life, there coexist a large number of relatively primitive organisms (bacteria, fungi, invertebrates and others), which have perfectly adapted to new conditions and are very stable. This is the logic of the evolutionary process.

General degeneration, or catagenesis

These are specific adaptations to certain specific living conditions that form within the same adaptation zone. Idioadaptations appear both during arogenesis and degeneration. These are private adaptations that do not significantly change the level of organization of organisms achieved in the process of evolution, but significantly facilitate their survival in these particular habitats.

For example, if we can consider a flower as the largest aromorphosis in the evolution of the plant world, then the shape and size of the flower are determined by the real conditions in which certain plant species exist, or by their systematic position.

The same applies, for example, to birds. The wing is an aromorphosis. The shape of the wings, flight methods (soaring, flapping) are a series of idioadaptations that do not fundamentally change the morphological or anatomical organization of birds. Idioadaptations include protective coloration, which is widespread in the animal world. Therefore, idioadaptations are often considered as signs of lower taxonomic categories - subspecies, species, or less often genera or families.

The relationship between different directions in evolution

The evolutionary process occurs continuously, and its main directions may change over time.

Aromorphoses or general degeneration, as rare processes in evolution, lead to an increase or decrease in the morphological and physiological organization of organisms and their occupation of a higher or lower adaptive zone. Within these adaptive zones, private adaptations (idioadaptations) begin to actively develop, ensuring a more subtle adaptation of organisms to specific habitats. For example, the appearance of a large group of mycorrhiza-forming fungi allows them to occupy a new adaptation zone associated with a large group of new habitats for fungi and plants. This is a biocenotic aromorphosis, further accompanied by a series of partial adaptations (idioadaptations) - the dispersal of different types of fungi to different host plants (boletus, boletus, boletus, etc.).

In the process of evolution, biological progress can be replaced by regression, aromorphosis - by general degeneration, and all this is accompanied by new idioadaptations. Each aromorphosis and each degeneration causes the dispersal of organisms into new habitats, realized through idioadaptations. This is the relationship between these directions of the evolutionary process. Based on these evolutionary transformations, organisms occupy new ecological niches and populate new habitats, that is, their active adaptive radiation occurs. For example, the emergence of vertebrates onto land (aromorphosis) caused their adaptive radiation and led to the formation of many taxonomic and ecological groups (predators, herbivores, rodents, insectivores, etc.) and new taxa (amphibians, reptiles, birds, mammals).

General characteristics of the directions of evolution in terms of changes in the level of organization and the nature of the prosperity of the species.

Convergence and divergence

Analysis of the mechanism of speciation shows that the result of this process is the appearance of one or several (two, three or more) related species.

Considering evolution as a whole, one can see that its result is the entire diversity of organisms living on Earth. Therefore, based on the results of the evolutionary process, two types of evolution can be distinguished - microevolution and macroevolution.

Microevolution is a set of speciation processes in which new (one or more) species of organisms arise from one species.

Microevolution is a kind of “elementary act of evolution”, accompanied by the emergence of a small number of species from one original species.

An example of microevolutionary processes is the emergence of two races of the birch moth moth, different species of finches on the Galapagos Islands, coastal species of gulls on the coast of the Northern Arctic Ocean(from Norway to Alaska), etc.

The development of the “white Ukrainian pig” breed can serve as an example of microevolution implemented by humans.

Thus, the result of microevolution is the emergence of new species from the original species, which is achieved through divergence.

Divergence is a process of divergence of characteristics, as a result of which new species appear or species that arose in the process of evolution differ from each other in various characteristics due to the adaptation of these species to different conditions of existence.

Macroevolution is the totality of all evolutionary processes as a result of which all the diversity of the organic world arose; these processes occur not only at the level of species, but also at the level of genus, family, class, etc.

The result of macroevolution is the entire diversity of the modern organic world, which arose both through divergence and convergence (convergence of characteristics).

Species that arose from different groups of organisms (for example, classes) can be convergent, that is, along with certain differences, they have common characteristics associated with adaptability to the same environment. Examples of convergent species are the shark, whale, and ichthyosaur (fossil reptile). These species have a fish-like shape and fins, as they are adapted to the aquatic environment. Another example of convergent organisms are butterflies, birds and bats, as they have wings and are adapted to an air-terrestrial lifestyle.

Consequently, during macroevolution, both divergence and convergence are possible.

Over the course of long historical development, macroevolution led to a dramatic change in the organic world as a whole. Thus, the modern organic world differs significantly from that of the Proterozoic or Mesozoic eras.

Paths and directions of evolution

As noted above, evolution occurs in two ways - divergent and convergent, and as a result of these processes, various types both in terms of their level of organization and the nature of adaptation to their habitats. Therefore, three evolutionary paths are distinguished according to the nature of changes in the level of organization of emerging organisms: idioadaptation, aromorphosis and degeneration.

1. Aromorphosis (arogenesis) is a path of evolution in which the level of organization of organisms increases compared to the original forms.

Aromorphoses include: the emergence of photosynthetic organisms from heterotrophs; the emergence of multicellular organisms from unicellular ones; the emergence of psilophytes from algae; the appearance of angiosperms with the presence of double fertilization and new shells of gymnosperm seeds; the emergence of organisms capable of feeding their young with milk, etc.

2. Idioadaptation (allogenesis) is a path of evolution in which new species appear that are no different in level of organization from the original species.

The species that emerged during idioadaptations differ from the original ones in characteristics that allow them to exist normally in different living conditions. Idioadaptations include the appearance of different types of finches on the Galapagos Islands, various rodents living in different conditions (hares, gophers, mouse-like rodents), and other examples.

3. Degeneration (catagenesis) - the path of evolution in which general level of newly emerged organisms decreases.

In some sources, evolutionary paths are called directions. In this case, it is necessary to indicate: directions of evolution according to the nature of changes in the level of organization, since there are directions of evolution according to the nature of prosperity. Based on this feature, two directions are distinguished - biological progress and biological regression.

Biological progress is a direction of evolution in which the number of populations, subspecies increases and the range (habitat) expands, while this group of organisms is in a state of constant speciation.

Currently, mammals, arthropods (from animals), and angiosperms (from plants) are in a state of biological progress. Biological progress does not mean an increase in the level of organization of organisms, but does not exclude it either.

Biological regression is a direction of evolution in which the range and number of organisms decrease, the rate of speciation slows down (the number of populations, subspecies, and species decreases).

Currently, reptiles, amphibians (from animals), and ferns (from plants) are in a state of biological regression. At the same time, human activity has a great influence on the state of progress or regression of organisms. Thus, many animal species have become extinct due to human influence (for example, Steller's cow seal, aurochs, etc.).

Adaptation of organisms to environmental conditions, its types and relativity

The first scientifically based definition of the species was given by Charles Darwin. Currently, this concept has been clarified from the standpoint of all modern theories, including from a genetic standpoint. In the modern interpretation, the formulation of the concept of “species” is as follows:

A species is a collection of all individuals that have the same hereditary morphological and physiological characteristics, are capable of freely interbreeding and produce normal fertile offspring, have the same genome, the same origin, occupy a certain living area and are adapted to the conditions of existence in it.

The criteria for the species and its ecological characteristics will be discussed below. In this subsection we present the mechanism of speciation.

Within populations, different individuals of these populations develop different characteristics due to mutational (hereditary) variability, therefore all individuals of a given population have certain differences from each other.

Traits that appear in individual individuals can be either beneficial or harmful to that organism in a given habitat. In the process of life, as a rule, those individuals that are more adapted to a given habitat survive. In individuals of different populations, these signs will be different, especially when the conditions of their habitats are very different.

Over time, the characteristics that distinguish individuals of one population from another accumulate, and the differences between them become more and more significant. As a result of these processes, several subspecies arise from one original species (their number is the same as how many populations of the species there were, living in different environmental conditions - 2, 3, etc.).

If different populations, located in different conditions of existence, are sufficiently isolated from each other, then mixing of characteristics due to hybridization of individuals does not occur. The differences between individuals of different populations become so significant that it is possible to state the emergence of new species (their individuals no longer interbreed and do not produce full-fledged fertile offspring).

In the process of speciation, new species arise that turn out to be well adapted to the conditions of their existence, which has always surprised and delighted people, and made religious people admire the “wisdom of the creator.” Let us consider the essence of the phenomenon of fitness, as well as the relativity of fitness.

Adaptation refers to certain characteristics of an organism that allow it to survive in given specific environmental conditions.

A striking example of adaptability is the white coloration of the mountain hare in winter. This color makes it invisible against the background of white snow cover.

In the process of evolution, many organisms have developed characteristics that make them very well adapted to their environment. Evolutionary theory revealed the cause and mechanism of the organism's adaptation to the conditions of its habitat and showed the materialistic essence of this process.

The reason for the appearance of adaptations to environmental conditions is hereditary variability that occurs under the influence of environmental conditions.

Mutations that arise, if they are useful, are fixed in the offspring due to the better survival of individuals possessing these characteristics.

A classic example of the emergence of adaptation in organisms to their environment was shown in the works of Charles Darwin.

Lives in England moth Birch moth, which has a light yellow color. Against the background of a light birch trunk, these butterflies are invisible, so most of them are preserved because they are invisible to birds.

If birch trees grow in the area of an enterprise that emits soot, then their trunks darken. Against their background, light-colored butterflies become noticeable, so they are easily eaten by birds. During the long temporary existence of the species of these butterflies, forms with dark colors appeared due to mutations. Dark-colored forms survived better under new conditions than light-colored ones. Thus, in England, two subspecies of moth butterflies (light and dark-colored forms) arose.

Reconstruction of production and improvement of technology taking into account the requirements led to the fact that enterprises stopped emitting soot and changing the color of birch trunks. This led to the fact that the dark-colored forms were not adapted to the new conditions, and the trait they acquired became not only not useful, but even harmful. On this basis, we can conclude that the fitness of organisms is relative: a strong, even short-term, change in environmental conditions can turn an organism adapted to its environment into an unadapted one: for example, a white hare, if the snow cover melts too early, will be more noticeable against the background darker field than if it were painted in a “summer” (gray) color.

There are several types of adaptation of organisms. Let's look at some of them.

1. Protective coloration - a color that allows the organism to be invisible against the background of the environment.

Examples: green coloration of aphids against the background of green cabbage leaves; dark coloring of the back of the fish on a dark background when viewed from above and light coloring of the belly on a light background when viewed from below; fish living in thickets of aquatic vegetation have a striped color (pike), etc.

2. Mimicry and camouflage.

Mimicry is when an organism is shaped like another organism. An example of mimicry is the wasp fly; the shape of its body resembles a wasp and thereby warns of a danger that does not exist, since this fly does not have a sting.

Camouflage consists of the fact that the organism takes the form of some object in the environment and becomes invisible.

An example is stick insects - insects shaped like fragments of plant stems; there are insects that have a leaf-like shape, etc.

3. Warning coloring - bright coloring that warns of danger. Examples: coloring of poisonous ladybugs, bees, wasps, bumblebees, etc.

4. Special adaptations of plants for the implementation of pollination processes. Wind-pollinated plants have long, hanging stamens, elongated stigmas sticking out in different directions with devices for collecting pollen, and other forms. Insect-pollinated plants have inflorescences, bright colors and exotic flower shapes to attract a specific type of insect, with the help of which pollination is realized.

5. Special forms animal behavior - threatening poses of sometimes harmless and sometimes dangerous reptiles, an ostrich burying its head in the sand, etc.

To summarize, it can be noted that due to the accumulation of differences arising due to mutations, the formation of new species adapted to their environment is possible, but this fitness is relative, since a change in conditions leads to a loss of the organism’s adaptability to a given environment.

Progress and regression in evolution. The evolutionary process as a whole continuously moves towards the maximum adaptation of living organisms to environmental conditions. Changing conditions often lead to the replacement of some devices with others. However, the same applies to adaptations of a broad nature that give organisms advantages in various environmental conditions. This is, for example, the importance of the lungs as a universal organ of gas exchange in terrestrial vertebrates or the flower as a perfect reproductive organ in angiosperms. Thus, biological progress can occur as a result of both private and general fixtures organisms. Biological progress should be understood as an increase in the adaptability of organisms to the environment, leading to an increase in the number and wider distribution of the species.

Evolutionary changes occurring in some species and larger taxa (families, orders) cannot always be recognized as progressive. In such cases they talk about biological regression. Biological regression is a decrease in the level of adaptability to living conditions, a decrease in the number of a species and the area of the species' range.

What are the ways to achieve biological progress?

Aromorphosis. The question of possible ways to achieve biological progress was developed by A. N. Severtsov, a major evolutionary scientist. One of the main such paths, according to Severtsov, is morphophysiological progress, or aromorphosis, i.e., the emergence during evolution of characteristics that significantly increase the level of organization of living organisms. Aromorphoses provide great advantages in the struggle for existence and open up the possibility of developing a new, previously inaccessible habitat.

ALEXEY NIKOLAEVICH SEVERTSOV (1866-1936) - domestic evolutionist. Author of studies on comparative anatomy of vertebrates. Created the theory of morphophysiological and biological progress and regression.

In the evolution of mammals, several major aromorphoses can be distinguished: the appearance of fur, viviparity, feeding the young with milk, the acquisition of a constant body temperature, the progressive development of the lungs, circulatory system and brain. The high general level of organization of mammals, achieved thanks to the listed aromorphic changes, allowed them to master all possible habitats and ultimately led to the emergence of higher primates and humans.

The formation of aromorphosis is a long process that occurs on the basis of hereditary variability and natural selection. Morphophysiological progress is the main path of evolution of the organic world. In the development of each major taxonomic group, aromorphoses can be found, as you will learn about in the following material.

Idioadaptation. In addition to such a major transformation as aromorphosis, during the evolution of individual groups a large number of small adaptations to certain environmental conditions arise. A. N. Severtsov called such adaptive changes idioadaptations.

Idioadaptations are adaptations of the living world to the environment, opening up for organisms the possibility of progressive development without a fundamental restructuring of their biological organization. An example of idioadaptation is the diversity of finch bird species described by Charles Darwin (Fig. 65). Different types finches, having a similar level of organization, were, however, able to acquire properties that allowed them to occupy completely different places in nature. Some species of finches have mastered feeding on plant fruits, others - seeds, and others have become insectivores.

Rice. 65. Diversity of finches in the Galapagos Islands

Despite the fact that general degeneration leads to a significant simplification of organization, species following this path can increase their numbers and range, that is, move along the path of biological progress.

Correlation of directions of evolution. The paths of evolution of the organic world either combine with each other or replace each other. Moreover, aromorphoses occur much less frequently than idioadaptations, but it is aromorphoses that determine new stages in the development of the organic world. Having emerged through aromorphosis, new, higher-organized groups of organisms occupy a different habitat. Further, evolution follows the path of idioadaptation, and sometimes degeneration, which provide organisms with the ability to settle into a new habitat for them (Fig. 67).

Rice. 67. Scheme of relationships between aromorphosis, ideological adaptation and degeneration

So, let us list the general features of the evolutionary process. First of all, this is the emergence of the adaptability of organisms, that is, their compliance with living conditions and the ability to change as these conditions change. Natural selection of hereditary changes in natural populations is the most important cause of fitness.

Another important characteristic of the evolutionary process is speciation, i.e., the constant emergence of new species. Over the course of evolution, there have been tens and perhaps hundreds of millions of species of living organisms on Earth.

And finally, the third integral property of the evolutionary process is the constant complication of life from primitive precellular forms up to humans.

Explain the terms: biological progress, biological regression, aromorphosis, idioadaptation.
Can the concepts “biological regression” and “degeneration” be considered identical? Justify your answer.
What is the evolutionary significance of aromorphosis and idioadaptation?

Bird class

The world's fauna is home to about 8,600 species of birds. This is a branch of higher vertebrates adapted for flight, whose body is covered with feathers. and the forelimbs turned into wings. Birds have many features similar to reptiles: an almost complete absence of skin glands; the presence of horny scales; similar structure of a number of parts of the skeleton and genitourinary system; identical development of the embryo; arterial blood in the right aortic arch, etc.

The features that distinguish birds from reptiles include: the progressive development of the organs of vision, hearing and coordination of movements together with the corresponding centers of the brain; intensification of breathing, blood circulation and digestion, together with the development of a heat-insulating cover and thermoregulation mechanisms, ensuring a constant high body temperature; four-chambered heart and complete separation of the circulatory system due to atrophy of the left aortic arch; more advanced forms of reproduction; a complex set of adaptations for flight in the air, facilitating wide possibilities for settlement and obtaining food. Adaptations for flight in birds include:

Streamlined body shape with modified limbs;

Transformation of the forelimbs into wings (this is associated with the formation of a keel on the sternum, bipedal walking and the appearance of a complex sacrum);

Development of complexly differentiated feather cover;

The presence of lightweight bones;

Development of the air sac system and double breathing;

Reduction of teeth, replaced by a horny beak, separation of the muscular stomach.

The body of birds is streamlined and consists of a head, neck, body and limbs. The necks of birds are of different lengths and are characterized by great mobility. The small head ends in a beak, consisting of a mandible and a mandible. The forelimbs are transformed into wings. The hind limbs serve as support for the entire body when moving on the ground. In the lower part they are covered with horny scales and in most birds end with four fingers.

Veils represented by thin, dry skin, devoid of glands. Just above the tail in most birds there is a special coccygeal gland. Its secretion serves to lubricate the feathers and protect them from water. The outside of the bird's body is covered with contour feathers, consisting of a hollow rod to which fans are attached. The lower part of the rod, immersed in the skin, is called the edge. The fan consists of numerous long beards of the first order, on which there are beards of the second order equipped with small hooks. The latter connect these beards to each other. The contour feathers that form the main part of the load-bearing plane of the wing are called flight feathers, and those that form the plane of the tail are called tail feathers. Under the contour feathers of many birds there are down feathers, the thin shafts of which are devoid of second-order barbs and do not form a closed fan. The role of feather cover in the life of birds is diverse: feathers form the load-bearing surface of the wings and tail, give a streamlined shape to the body, provide heat retention and mechanical protection.

Skeleton Birds are lightweight and durable. Bones have cavities filled with air. Many bones grow together - the bones of the skull, pelvis. The spine is divided into five sections: cervical, thoracic, lumbar, sacral and caudal. The cervical region has significant mobility, while the remaining parts of the spine are inactive and firmly connected to each other. The thoracic vertebrae have a pair of ribs articulated with the sternum. The ribs have hook-shaped processes that overlap the adjacent ribs with their ends; this gives the rib cage strength. In flying birds and penguins, a keel is located on the sternum; strong pectoral muscles. The posterior thoracic, lumbar, sacral and part of the caudal vertebrae fuse with the pelvic bones, forming a complex sacrum that creates a strong support for the legs. The last tail vertebrae fuse into the coccygeal bone, which serves as a support for the tail feathers.

The skull of birds is characterized by lightness, has large eye sockets and ends with a beak. The bones of the skull grow together until the sutures between them completely disappear.

The shoulder girdle consists of three pairs of bones: crow bones, scapulae, and clavicles. The clavicles are fused at their lower ends and form a fork, characteristic of birds. The wing skeleton consists of a large humerus, two forearm bones (ulna and radius), fused bones of the carpus, metacarpus and reduced phalanges of three fingers. The pelvic girdle consists of three pairs of bones: iliac, ischial and pubic, fused with each other. The lower ends of the pubic and ischial bones are not connected, so the pelvic girdle remains open from below. This has implications for egg laying. The skeleton of the hind limb consists of the femur, two fused tibia and fibula and the foot. The skeleton of the foot includes the tarsus (fused bones of the metatarsus and tarsus) and the phalanges of the toes.

Musculature birds are more differentiated than reptiles. The most developed are the pectoral muscles, which move the wings, as well as the muscles of the hind limbs, which bear a large load when walking.

Digestive system begins with a beak, partially replacing teeth; The tongue is located in the oral cavity. The oral cavity passes into a short pharynx, and that into a long esophagus, which in many birds has a voluminous extension - a goiter. In the crop, food accumulates and softens. The lower part of the esophagus continues into the glandular stomach, which has the shape of a tube. There, the softened food is exposed to digestive enzymes secreted by the stomach lining. From the glandular stomach, food enters the muscular stomach, which has thick muscular walls and is lined on the inside with a horny cuticle. Here the grinding of food occurs with the help of both muscle contraction and small pebbles swallowed by birds. From the stomach, food enters the duodenum, where the ducts of the liver and pancreas open. The small intestine becomes a short rectum, which opens into the cloaca.

Respiratory organs consist of lungs, air sacs and airways that begin with the nostrils located at the base of the beak. From the nasal cavity, air enters the larynx and then into the trachea. At the point where the trachea divides into two bronchi, the lower, or singing larynx, characteristic of birds, is located. It plays the role of the vocal apparatus. Bird lungs are dense, spongy bodies. The bronchi entering the lungs branch. Some bronchi pass through the lungs and end in thin-walled air sacs. They are located between internal organs, between muscles, under the skin and in the cavities of tubular bones. Air sacs play an important role in breathing and lighten the weight of the bird during flight. When the wings rise (inhale), air enters the lungs, partially releases oxygen and passes into the air sacs. Blood oxidation does not occur in the air sacs. When the wings lower (exhale), air from the bags again enters the lungs. Blood oxidizes in the lungs both during inhalation and exhalation. This type of breathing is called double breathing.

Circulatory system provides a high level of oxidative processes in the body of birds. Unlike reptiles, the blood circulation of birds is characterized by complete separation of arterial and venous blood. The four-chambered heart of birds has a right and left atrium and a right and left ventricle. In addition, one of the aortic arches disappears, which eliminates the possibility of mixing blood. The systemic circulation begins with the right aortic arch, which goes around the heart and passes into the dorsal aorta, which runs along the spine. Arteries extend from it to all parts of the body. Venous blood from the anterior part of the body collects into the paired vena cava, and from the posterior part of the body into the unpaired posterior vena cava. These veins drain into the right atrium, from where blood flows into the right ventricle.

The pulmonary circulation begins with the pulmonary artery emerging from the right ventricle. It carries venous blood to the lungs, where it is oxidized. From the lungs, arterial blood returns to the left atrium through the pulmonary veins. The high metabolism of birds is ensured by the energetic work of the heart and rapid blood circulation through the vessels. Thus, in small birds, during flight, the heart contracts more than 1000 times/min.

Excretory organs birds are represented by paired secondary (pelvic) kidneys. They are large in size and lie in the recess of the pelvic bones. The ureters extend from the kidneys and open into the cloaca. There is no bladder, so urine is not retained in the body.

Nervous system in birds it is more difficult than in reptiles. The brain is distinguished by its large hemispheres, significant development of the visual thalamus and large cerebellum. Enlargement of the midbrain is associated with increased vision in birds. The large cerebellum is responsible for flight, which requires precisely coordinated movements. There are 12 pairs of cranial nerves originating from the brain.

From sense organs Vision is especially well developed: the eyes are large, equipped with upper and lower eyelids and a nictitating membrane (third eyelid). Color vision. Greater visual acuity is provided by double accommodation: a change in the shape of the lens and the distance between the lens and the retina. The hearing organs consist of the inner and middle ear, the eardrum is somewhat recessed. The olfactory organs are poorly developed.

Reproduction occurs by laying eggs. Birds are dioecious; sexual dimorphism is pronounced; fertilization is internal. Reproductive system The male consists of two testes and vas deferens, opening into the cloaca. The left ovary and oviduct develop, which opens into the cloaca. After fertilization, the egg slowly moves through the oviduct and becomes covered with a protein coat. In the lower, expanded part of the oviduct (uterus), it is covered with thin subhull membranes and shells and enters the cloaca through the narrow vagina. The development of the embryo occurs under the protection of the embryonic membranes.

The development of the avian embryo begins from a small germinal disc located on the surface of the yolk. Bird eggs are large in size, as they contain many nutrients in the form of yolk and white. The yolk is held on ropes (consisting of thick white) in the center of the egg. Due to its low specific gravity, the germinal disk is located on top in any position of the egg. It has great value during incubation, as the embryo receives more warmth. The white is covered with two subshell membranes, diverging at the blunt end of the egg and forming an air chamber. The outside of the egg is covered with a calcareous shell, which has a large number of pores. Through the pores, gas exchange occurs between the embryo and the external environment. The shell is covered with a thin supershell membrane that protects the egg from the penetration of bacteria. The development of the embryo occurs under the protection of the embryonic membranes.

Incubation in birds lasts for different periods of time: in a pigeon it lasts 16-18 days, in a chicken – 21 days, in an African ostrich – up to 40 days. After incubation, the eggs hatch into chicks. In some birds, the chicks are covered with thick down and are capable of an independent lifestyle (brood birds). In others, the chicks are not covered with feathers and for a long time fed by parents (chickling birds). Brood animals include Galliformes, Anseriformes, cranes, and ostriches. Chicks include passerines, woodpeckers, and pigeons. There is an intermediate group - these are seagulls, diurnal predators; According to their development, they can be classified as brood animals, and according to the nature of their feeding, they can be classified as nestlings.

Sedentary birds live in certain territories, nomadic birds fly to the south, migratory birds fly to warm countries and spend the winter there.

The class Birds includes the superorders Penguins, Ratites, or Ostriches, Keel-breasted. The geographical distribution of birds is wide. And they adapted to a variety of living conditions.

The bulk of birds in cultural landscapes (parks, gardens, meadows, fields) are representatives of the passerine order. These are insectivorous birds of small to medium size. These include sparrows, tits, swallows, nightingales, magpies, jackdaws, larks, etc.

Birds that live in forests have adapted to climb trees; their claws are very sharp and strongly curved. They can feed on insect larvae and wild berries. Forest birds include woodpeckers, wood grouse, black grouse, etc.

Some birds have adapted to living in ponds and swamps: they have membranes on their feet; in addition, there is the coccygeal gland, the secretions of which are needed to protect against water. Waterfowl include mallard ducks, penguins, etc.

The open spaces of steppes and deserts are inhabited by birds that move mainly by running or walking: the wings are short and wide, the legs are strong with short toes. These include cranes, ostriches, and bustards. They feed on plant foods, insects, and sometimes small rodents.

Among the predators, there are diurnal ones that hunt during the day (vultures, hawks, falcons, eagles, etc.), and nocturnal ones (owls, eagle owls). They feed on animals, sometimes fish and insects. They have sharp claws, a powerful beak and good eyesight.

Birds regulate the number of insects and small rodents. Participate in seed distribution and pollination. Many decorate natural landscapes and enliven them with their singing. The benefits and harms of birds are relative. They support natural foci of human diseases as guardians and feeders of carriers of these diseases; birds take part in the circulation of viral diseases (ornithosis, influenza, encephalitis).

Test

Type : test on the topic “Reptiles and Birds”
Item : biology
Class : 7
Compiled by tasks : Gareishina Inna Georgievna

Among large species of crocodiles, some individuals can live up to 120 years; cats rarely live longer than 12 years. How many times longer can a crocodile live? Write down the answer as a number.
Penguins are inhabitants of the southern hemisphere of the Earth. The largest penguin is the emperor, about 1 m tall, and comes to nest on the coldest continent - Antarctica. The smallest - the little penguin, only about 40 cm tall, nests almost on the equator, on the Galapagos Islands. How many centimeters is the emperor penguin taller than the little one? Write down the answer in centimeters, as a number.
The largest bird on Earth is the African ostrich. His height (more than 2.5 m) exceeds the height of a person. He can't fly. Possessing powerful legs, this bird is capable of running at a speed of 60 km per hour. How many kilometers can an ostrich run in 10 minutes? Write down the answer as a number.
Weight chicken egg approximately 60 grams, and African ostrich eggs - 25 times more. What is the mass of an ostrich egg? Write down the answer as a number.
In the class of reptiles or reptiles greatest number There are approximately 3,500 species in the order of lizards, and there are 500 fewer species in the order of snakes. The order of turtles is approximately 10 times smaller in number than snakes, and the order of crocodiles has 15 times fewer species than turtles. The beaked order includes tuataria, which survive only in New Zealand; there are 10 times fewer of them than crocodiles. How many species does each reptile order contain? The answer will be four numbers.
The pied flycatcher brings about 500 invertebrate animals to its chicks per day. How many invertebrates will she feed to her chicks in 16 days until they fly out of the nest? Write down the answer as a number.
The gray heron has 3-7 greenish-blue eggs in a full clutch. How many chicks can a pair of herons have in three years if each clutch contains 6 eggs? Write down the answer as a number.
Sparrows can be considered typical granivorous birds, but they feed their chicks with invertebrate animals, mainly insects. During the period of feeding the chicks, in just two weeks, a pair of sparrows feeds their voracious babies about 1.4 kg of insects, spiders and mollusks. How many grams of invertebrates do sparrows feed their chicks in 1 day? Write down the answer as a number.
The decline in the number of Galapagos tortoises began in the 18th century, and populations are currently being restored by humans. The largest land turtle lives on the Galapagos Islands; the length of its shell can reach one and a half meters, and its weight can reach two hundred kilograms. The largest sea turtle is 50 cm longer, and its weight is 2.5 times more than that of a land species. What is the mass and body length of a sea turtle? The answer will be two numbers.

Establish a correspondence between the trait and the class of vertebrates for which it is characteristic. To do this, select a position from the second column for each element of the first column.

SIGN A) four-chambered heart B) dry, thin skin, covered with horny scales and plates C) well-developed care for offspring

D) the blood in the heart is mixed

D) body temperature is high and constant

E) three-chambered heart with an incomplete septum in the ventricle

1) Reptiles 2) Birds

The tail helps him hunt. The blow of its tail is dangerous even for large animals. Covered with horny plates, it is as heavy as a log. With its powerful tail, this animal knocks its prey off its feet, throws it up and catches it with its huge toothy mouth. 1) iguana, 2) monitor lizard, 3) crocodile, 4) anaconda, 5) moloch. The answer will be one number.
Adaptations of birds for flight include:

Modified limbs
Good sense of smell
One circle of blood circulation and pulmonary respiration
Hollow bones in the skeleton
Presence of duodenum and rectum
No bladder

The answer will be a series of numbers.

Choose the correct statements. The answer will be a series of numbers.

The respiratory surface of the lizard's lungs is larger than that of the newt
All reptiles have a three-chambered heart
Reptiles lay eggs
In reptiles of the northern regions, live births are more common
The lizard heart has a complete interventricular septum
Reptiles have many sweat and sebaceous glands in their skin.

In the food chain, the kite is a secondary consumer because it:

Heterotroph
Predator
Uses solar energy
Regulates the number of animals it eats
Mineralizes organic residues
Feeds on weak and sick animals

The answer will be a series of numbers.

Significant evolutionary, progressive acquisitions of birds are:

The brain has five sections
Intensive metabolism
Mixed blood in the heart
Bone skull
Beak without teeth
Lightness and strength of the skeleton

The answer will be a series of numbers.

Correct Answers

Job number	Answer
1	10
2	60
3	10
4	1500
5	3000, 300, 20, 2
6	8000
7	18
8	100
9	200, 500
10	2,1,2,1,2,1
11	3
12	1,4,6
13	1,3,4
14	2,4,6
15	2,5,6

Lesson objectives:

Ensure that students acquire knowledge about the life processes of birds, their structural features internal organs in connection with functions, adaptability to flight.
Show the complexity of the organization of the internal structure of birds compared to reptiles.
To teach to recognize the organ systems of the bird class, to establish the relationship between the structure and function of organs.
To teach how to identify the adaptability of organisms to their environment.

Lesson type: lesson of learning new material.

Lesson format: a lesson in acquiring new knowledge through independent work, group work, and partial search method.

Equipment:

bird skeleton, model “Vertebrate Brain”;
tables “Bird class. Pigeon", "Main classes of vertebrates"

PROGRESS OF THE LESSON

I. Organizational moment

II. Updating of reference knowledge

“An ounce of experience and labor is worth more than a ton of theory.” (Dewey).

Millions of years ago the first birds appeared. And the hitherto gloomy world, inhabited only by dinosaurs, resounded with birdsong. And millions of years later, a man walked the earth who was able to appreciate this singing. The man raised his head, and there was a lark in the sky! Sings, sings, flutters its wings!
The man raised his head up and saw a stork that had built a nest on the top of a tall oak tree, just above the roof of his house. The stork stands on one leg, clicks its beak, knocks out fractions, and wants to please the stork!
The man raised his head up - and there the eagle soars, freely, easily! “If only I could do that too,” the man thought, built wings and threw himself down from the bell tower. He threw himself down more than once before he soared up, relying not on the strength of his muscles, but on the strength of his mind. And aviation was born. Airplanes fly faster than sound, far away from the birds. But in terms of flight efficiency, birds are unattainable. A titmouse flies 100 km on one gram of fat!
Young navigators are graduating from military schools. A ship or plane can take you to any point on earth. But birds, returning to us after wintering, find landmarks known only to them and land exactly on the same clearing from which they started in the fall!
Birds see perfectly, and it’s not for nothing that we say: “Vigilant as a falcon!” They hear and sing perfectly! The autumn garden is boring without them, and we rejoice at their return in the spring. What can I say! Birds are birds!
Today in class you and I will be young researchers, and I will be your supervisor. We will have to solve a difficult problem together: