The evolution of the organic world is long and difficult process carried out on different levels organization of living matter and flowing in different directions. The development of wildlife came from lower forms, having a relatively simple structure, to more and more complex forms. Simultaneously inside individual groups organisms developed special adaptations (adaptations) that allowed them to exist in specific habitats. For example, in many aquatic animals, membranes appear between the fingers, which facilitate swimming (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 adaptations and degeneration.
Aromorphosis (or arogenesis) is a major evolutionary change leading to a general complication of the structure and functions of organisms and allowing the latter to occupy fundamentally new habitats or significantly increase the competitive ability of organisms in existing habitats. Aromorphoses allow you to move into new habitats (that is, go into new adaptation zones). Therefore, aromorphoses are relatively rare phenomena in the living world and are of a fundamental nature, providing big influence for the evolution of organisms.
Adaptation level or adaptive zone is called certain type habitats with characteristic ecological conditions or a complex of certain adaptations characteristic of a particular group of organisms ( general terms and Conditions life or similar ways of assimilation of some vital important resources). For example, the adaptive zone of birds is the development airspace, which provided 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 that are inaccessible to other animals (rivers, seas, mountains, etc.), the ability to long-distance migrations (flights), etc. Therefore, flight is a major evolutionary acquisition (aromorphosis).
Most vivid examples multicellularity and the appearance of a sexual mode of reproduction can serve as aromorphoses. Multicellularity contributed to the emergence and specialization of tissues, led to the complication of the morphology and anatomy of many groups of organisms, both plants and animals. sexual reproduction significantly expanded the adaptive abilities of organisms (combinative variability).
Aromorphoses provided animals with more efficient ways of feeding and increased metabolic efficiency - for example, the appearance of jaws in animals made it possible to switch from passive feeding to active feeding; the release of the alimentary 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 various sections (the appearance of the stomach, intestines, digestive glands, the rapid removal of unnecessary products). This significantly increased the chances of survival of organisms even in places with a low content of nutrient resources.
The largest aromorphosis in the evolution of animals was warm-bloodedness, which dramatically 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 kingdom, we can also recall the formation of an internal cavity of organisms (primary and secondary), the appearance of a skeleton (internal or external), the development nervous system and especially the complication of the structure and functions of the brain (the appearance complex reflexes, learning, thinking, second signal system in humans, etc.) and many other examples.
In plants, major aromorphoses are: the appearance of a conducting system that connected different parts of the plant into a single whole; the formation of a shoot - a vital organ that provided plants with all aspects of life and reproduction; the formation of a seed - a reproductive organ that occurs sexually, the development and maturation of which is provided 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 shortage 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 competitiveness.
Arogenesis can also occur at the interspecies (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 mycorrhiza (symbiosis of fungi and plant roots) and lichens (association of fungi and algae). These types of associations allowed symbionts to live in places where they would never have settled separately (on poor soils, on rocks, etc.). Especially 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 single organism resembling plants. The largest aromorphosis of this type is the eukaryotic cell, consisting of different organisms(prokaryotes), completely lost their individuality and turned into organelles. The eukaryotic cell has a more active and economical metabolism than the prokaryotic cell and has 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 are preserved 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 little specialized forms of organisms, since they tolerate changes more easily. environment and it is easier for them to get used to new environments. Specialized forms adapted to certain, often quite narrowly limited conditions life, usually perish when such conditions change abruptly. That is why in nature, along with highly organized and specialized forms of life, coexists big number relatively primitive organisms (bacteria, fungi, invertebrates, and others) that have perfectly adapted to new conditions and are very stable. Such is the logic of the evolutionary process.
General degeneration, or catagenesis
These are specific adaptations to certain specific habitat conditions that are formed within the same adaptation zone. Idioadaptations are manifested both during arogenesis and during degeneration. These are particular 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 a flower we can consider as the largest aromorphosis in evolution flora, then the shapes and sizes of the flower are already determined by those real conditions, in which certain plant species exist, or their systematic position.
The same applies, for example, to birds. The wing is an aromorphosis. The shape of the wings, flight methods (soaring, flywheel) - a series of idioadaptation that does 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, less often genera or families.
The ratio of different directions in evolution
The evolutionary process is continuous, and its main directions can 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 (idioadaptation) begin to actively develop, providing a more subtle adaptation of organisms to specific habitats. For example, the appearance of a large group of mycorrhizal 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, followed by a series of particular adaptations (idioadaptation) - resettlement different types fungi on different host plants (boletus, boletus, boletus, etc.).
In the process of evolution, biological progress can be replaced by regression, aromorphoses - by general degeneration, and all this is accompanied by new idioadaptations. Each aromorphosis and each degeneration cause the resettlement of organisms in new habitats, realized through idioadaptation. Such is the ratio of 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 on 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 by changing the level of organization and the nature of the prosperity of the species.
Convergence and Divergence
An analysis of the mechanism of speciation shows that the result of this process is the appearance of one or more (two, three or more) closely related species.
Considering evolution as a whole, one can see that its result is the 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, as it were, an “elementary act of evolution”, accompanied by the appearance of a small number of species from one initial species.
An example of micro evolutionary processes is the emergence of two races of the nocturnal moth, different types of finches on Galapagos Islands, coastal species of gulls on the North coast Arctic Ocean(from Norway to Alaska), etc.
The breeding 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 carried out due to divergence.
Divergence is a process of divergence of characteristics, as a result of which new species appear or species that have arisen 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 - the totality of all evolutionary processes, as a result of which all the diversity of the organic world has arisen; these processes take place not only at the species level, but also at the level of the genus, family, class, etc.
The result of macroevolution is the entire diversity of the modern organic world, which arose both due to divergence and convergence (convergence of features).
species that originated from different groups organisms (for example, classes) can be convergent, i.e., along with certain differences, they have common features associated with adaptability to one environment. Examples of convergent species are shark, whale and ichthyosaur (fossil reptile). These species have a fish-like shape, fins, as they are adapted to aquatic environment. Other examples of convergent organisms are butterflies, birds, and the bats, since they have wings and are adapted to an air-ground lifestyle.
Consequently, during the course of macroevolution, both divergence and convergence are possible.
For a long time historical development macroevolution led to drastic change the organic world as a whole. Yes, modern organic world significantly different from that of the Proterozoic or Mesozoic eras.
Ways and directions of evolution
As noted above, evolution is carried out in two ways - divergent and convergent, and as a result of these processes, different kinds both in terms of their level of organization and the nature of adaptation to habitats. Therefore, three paths of evolution are distinguished according to the nature of the change in the level of organization of emerging organisms: idioadaptation, aromorphosis and degeneration.
1. Aromorphosis (arogenesis) - the path of evolution, in which the level of organization of organisms increases in comparison with the original forms.
Aromorphoses include: the emergence of photosynthetic organisms from heterotrophs; appearance multicellular organisms from unicellular; the emergence of psilophytes from algae; the appearance of angiosperms with the presence of double fertilization and new shells in the seed from gymnosperms; the emergence of organisms capable of feeding their young with milk, etc.
2. Idioadaptation (allogenesis) - the path of evolution, in which new species appear, which do not differ from the original species in terms of the level of organization.
The species that have arisen during idioadaptation differ from the original ones in features that allow them to exist normally in various conditions habitat. Idioadaptation can be attributed to the appearance of different types of finches on the Galapagos Islands, various rodents living in different conditions(hares, ground squirrels, mouse-like rodents), and other examples.
3. Degeneration (catagenesis) - the path of evolution, in which general level newly emerged organisms is reduced.
In some sources, the paths of evolution are called directions. In this case, it is necessary to indicate: the direction of evolution according to the nature of the change in the level of organization, since there are directions of evolution according to the nature of prosperity. By given feature There are two directions - biological progress and biological regression.
biological progress- this is such a direction of evolution, in which the number of populations, subspecies increases and the range (habitat) expands, while this group organisms are in a state of constant speciation.
Currently, mammals, arthropods (from animals), 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 it does not exclude it either.
Biological regression - the direction of evolution, in which the range and number of organisms decrease, the rate of speciation slows down (the number of populations, subspecies, species decreases).
Currently able biological regression there are reptiles, amphibians (from animals), ferns (from plants). 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 impact (for example, the Steller's cow seal, aurochs, etc.).
Adaptability of organisms to environmental conditions, its types and relativity
The first scientifically substantiated definition of the species was given by Charles Darwin. At present, this concept has been clarified from the standpoint of all modern theories, including from a genetic point of view. In the modern interpretation, the wording of the concept of "kind" is as follows:
A species is a collection of all individuals that have the same hereditary morphological and physiological characteristics, are able to freely interbreed 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 characteristic will be discussed further. In this subsection, we present the mechanism of speciation.
Within populations, in various individuals of these populations, due to mutational (hereditary) variability, various signs Therefore, all individuals of this population have certain differences from each other.
The 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 features 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 initial species (their number is the same as the number of populations of the species living in different environmental conditions - 2, 3, etc.).
If different populations under different conditions of existence are sufficiently isolated from each other, then mixing of characters due to hybridization of individuals does not occur. The differences between individuals of different populations become so significant that it is possible to ascertain the emergence of new species (their individuals no longer interbreed and do not give full-fledged fertile offspring).
In the process of speciation, new species arise that are well adapted to the conditions of their existence, which has always surprised and delighted man, and religious people forced to admire the "wisdom of the creator." Consider the essence of the phenomenon of fitness, as well as the relativity of fitness.
Adaptation is called certain features of organisms that allow it to survive in given specific environmental conditions.
A striking example of adaptability is the white color of the hare in winter period. This coloration makes it invisible against the background of white snow cover.
In the process of evolution, many organisms have developed signs due to which they have adapted very well to their environment. evolutionary theory revealed the cause and mechanism of the organism's adaptability to the conditions of its environment, 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.
The resulting mutations, if useful, are fixed in the offspring due to the better survival of individuals with these traits.
A classic example of the emergence of adaptability in organisms to the environment was shown in the works of Charles Darwin.
In England, there is a 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, since they are invisible to birds.
If birch trees grow in the area of a soot-producing enterprise, then their trunks darken. Against their background, light-colored butterflies become noticeable, therefore they are easily eaten by birds. In the process of a long temporary existence of the species of these butterflies, forms with a dark color appeared due to mutations. Dark-colored forms survived better under new conditions than light-colored ones. So, 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 acquired by them 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 the environment into an unadapted one: for example, a mountain hare with too early a snow cover will be more noticeable against the background dark field than if it were painted in "summer" (gray) color.
There are several types of adaptability in organisms. Let's consider some of them.
1. Protective coloration - a color that allows the body to be invisible against the background of the environment.
Examples: green coloring of aphids against the background of green cabbage leaves; dark coloration of the back of the fish against a dark background when viewed from above and light coloration of the belly against a light background when viewed from below; fish living in thickets of aquatic vegetation have a striped color (pike), etc.
2. Mimicry and disguise.
Mimicry is the fact that an organism is similar in shape to another organism. An example of mimicry is the wasp fly, the shape of its body resembles a wasp and this warns of a danger that does not exist, since this fly does not have a sting.
Camouflage consists in the fact that the organism takes the form of some object of 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 color - a bright color that warns of danger. Examples: coloring 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, sticking out in different sides stigmas of pistils with devices for trapping pollen and other forms. Insect pollinated plants have inflorescences, bright colors and exotic flower shapes to attract a certain kind insects that carry out pollination.
5. special shapes animal behavior - threatening poses of sometimes harmless, and sometimes dangerous reptiles, ostrich burying its head in the sand, etc.
Summing up, it can be noted that due to the accumulation of differences arising due to mutations, it is possible to form new species adapted to their environment, but this fitness is relative, since changing conditions lead to the loss of the organism's adaptability to this environment.
There are many hypotheses regarding possible ways origin of the main kingdoms of wildlife. Let us consider the main paths of the historical development of the kingdoms of plants and animals, which are the most studied from this point of view.
The number of species of currently existing plants reaches 500,000, of which about 300,000 are flowering. The first autotrophs were cyanideans and partly green algae. Their remains are found in rocks even Archean age.
AT Proterozoic many lived in the seas different representatives green and golden algae. At the same time, apparently, algae attached to the bottom appeared. On the surface of lifeless land, the first soil is created, resulting from the action of abiotic ( climatic conditions) and biotic (presence of bacteria and cyanide) conditions.
AT Paleozoic in the plant kingdom, a major evolutionary event occurs - plants move to land. However, in the early periods of this era, plants still inhabit mainly the seas. There are green and brown algae attached to the bottom, and in the water column there are diatoms, golden, euglenoids. At the end Ordovician and early Silurian and the appearance of the first terrestrial plants - psilophytes, which covered coastal areas of land with a continuous green carpet, was noted. There are rearrangements in the conducting system and integumentary tissues of plants: a conducting vascular system with poorly differentiated phloem and xylem, cuticle and stomata. Psilophytes were more securely attached to the substrate with the help of dichotomously branched lower axes. Some have primitive leaves. Psilophytes occupied an intermediate position between terrestrial vascular plants and algae.
Further evolution of plants in terrestrial conditions led to an increase in the compactness of the body, the appearance of roots, the development of epidermal tissue with thick walls impregnated with wax-like substances, a change in the methods of reproduction, distribution, etc.
From the moment they land on land, plants develop in two main directions: gametophyte and sporophyte. The gametophyte direction was represented by mosses, the sporophyte direction was represented by other plants. The sporophyte branch turned out to be more adapted to the terrestrial way of life. In these plants, the root and conducting systems, integumentary and mechanical tissues gradually improved and became more complicated. Already in Devonian there are lush forests of horsetails, club mosses, ferns and ancient gymnosperms (cordaites).in carbon these forests are even more common, and the climate is humid and evenly warm throughout the year. Plants reach 40 m in height.
In the same period, the first seed woody plants from gymnosperms are found, the flowering of which falls at the end carbon – Permian period. Their difference from fern-like and floating-like ones is the transformation of megasporangium into an ovule. Complete release in some plants, the process of sexual reproduction from water. Thus, pollination in gymnosperms is carried out by the wind, and after fertilization, the ovule turns into a seed, and the seeds have adaptations for dispersal by wind and animals.
Mesozoic The era is characterized by intensive mining processes: the Urals, Tien Shan, Altai, etc. appear. The climate continues to dry out, and the areas of oceans and seas are shrinking. AT triassic the development of deserts, the extinction of giant ferns, tree-like horsetails, and club mosses were noted. AT jurassic period, against the backdrop of the flowering of gymnosperms, the first angiosperms appear and bennetite- a prototype of flowering plants.
Angiosperms are gradually spreading, conquering all the continents, which is associated with the presence of a number of advantages. Angiosperms have a highly developed conducting system, a flower and a fruit (the embryo is supplied with a supply nutrients). In the process of evolution, the flower undergoes significant changes. Plants with cross-pollination were favored. Pollinators were attracted by the aroma of nectar, the bright color of the flower.
Cenozoic era is considered the heyday of angiosperms. At the beginning of the Cenozoic, a warm climate is still maintained. In the Neogene and Paleogene, the Andes, the Pyrenees, the Himalayas are formed, the Mediterranean, Black, Caspian and Aral Sea. Botanical and geographical areas close to modern ones are being formed. In the north, coniferous forests predominate, in the south - chestnut-beech forests with the participation of sequoia and ginkgo. The whole of Europe was covered with lush forests of such trees as oak, birch, pine, chestnut, beech, vine, walnut, etc. The climate is warm and temperate.
In the Quaternary Cenozoic era (2-3 million years ago), the amount of precipitation increased and glaciation of a significant part of the Earth began, which caused the extinction or retreat of heat-loving tertiary vegetation to the south. Cold-resistant herbaceous and shrubby plants appeared. On the vast territories forests were replaced by steppe, semi-desert and desert. Vegetation appears with pronounced seasonality in the development cycle, and modern phytocenoses are formed.
Thus, the main features of the evolution of the plant kingdom are as follows:
1. Transition from haploid to diploid. In many algae and mosses, all cells (except the zygote) are haploid. In ferns, an independent gametophyte is still present, but already in gymnosperms and angiosperms, a complete reduction of the gametophyte and a transition to the diploid phase are observed.
2. The release of the process of sexual reproduction from the presence of water.
3. Differentiation of the body with the transition to terrestrial conditions: root, stem, leaf.
4. Specialization of pollination (insects).
Types of evolutionary changes.
The main types of evolutionary changes include: parallelism, convergence and divergence.
Parallelism is an evolutionary change that results in the formation of similar traits in related organisms. For example, among mammals, cetaceans and pinnipeds, independently of each other, switched to living in the aquatic environment and acquired the corresponding adaptations - flippers. Known general resemblance have unrelated mammals tropical zone, living on different continents, in similar climatic conditions (Fig. 89).
Convergence is a type of evolutionary change, as a result of which unrelated organisms acquire similar features (Fig. 90). Two or more species not closely related become more and more similar friend on a friend. This type of evolutionary change is the result of adaptations to similar conditions. external environment.
Convergent changes affect only organs that are directly related to the same environmental factors. Chameleons and climbing agamas that live on tree branches are very similar in appearance, although they belong to different suborders. In marsupial and placental mammals, as a result of a similar way of life, similar structural features independently of each other arose. Similar are the European mole and the marsupial mole, the marsupial flyer and the flying squirrel. Convergent similarity is observed even in groups of animals that are very far apart from each other in the systematic position. Birds and butterflies have wings, but the origin of these organs is different. In the first case, these are altered limbs, in the second, skin folds.
Divergence is the most general type evolutionary process, the basis for the formation of new systematic groups.
Divergence (from lat.divergantia - divergence) - divergent evolution. The divergence process is usually represented as evolutionary tree with divergent branches (Fig. 91). This is an image of divergent evolution, or radiation: a common ancestor gave rise to two or more forms, which, in turn, became the ancestors of many species and genera. Divergence almost always reflects the expansion of adaptation to new living conditions. The class of mammals broke up into numerous orders, whose representatives differ in structure, lifestyle, and the nature of physiological and behavioral adaptations (insectivores, bats, carnivores, cetaceans, etc.).
The main directions of evolution.
The development of living nature went from simple to complex and had a progressive character. Along with this, the adaptation of species to specific living conditions took place, their specialization was carried out.
To understand the historical development of the organic world, it is important to determine the main lines of evolution. A significant contribution to the development of the problem of evolution was made by prominent Russian scientists A. N. Severtsov and I. I. Shmalgauzen. They found that the main directions of evolution are aromorphosis, idioadaptation and degeneration (Fig. 92).
Aromorphosis (from the Greek. airomorphosis - I raise the form) is such a large-scale, evolutionary changes that lead to a general rise in the organization, increase the intensity of life, but are not narrow adaptations to sharply limited conditions of existence. Aromorphoses give significant advantages in the struggle for existence, make it possible to move into new environment habitat.
Aromorphoses in animals include the appearance of live birth, the ability to maintain a constant body temperature, the emergence of a closed circulatory system, and in plants - the appearance of a flower, a vascular system, the ability to maintain and regulate gas exchange in leaves.
By way of aromorphosis, large systematic groups, a rank higher than the family. Aromorphoses contribute to increased survival and reduced mortality in populations. The number of organisms increases, their range expands, new ones form. populations accelerates the formation of new species. All this is the essence of biological progress, or the victory of a species (another systematic unit) in the struggle for existence.
Idioadaptation (from the Greek idios - peculiar and lat. adaptatio - adaptation) is a small evolutionary change that increases the adaptability of organisms to certain environmental conditions. In contrast to aromorphosis, idioadaptation is not accompanied by a change in the main features of the organization, a general rise in its level and an increase in the intensity of the organism's vital activity.
Examples of idioadaptations are the protective coloration of animals or the adaptation of some fish (flounder, catfish) to life at the bottom - flattening of the body, coloring to match the color of the ground, development of antennae, and so on. Another example is flight adaptations in some mammalian species (bats, flying squirrels).
An example of idioadaptation in plants is a variety of adaptations to cross-pollination of a flower by insects or wind, adaptations to seed dispersal.
Usually, small systematic groups - species, genera, families - arise in the process of evolution through idioadaptation. Idioadaptation, as well as aromorphosis, leads to an increase in the number of a species, an expansion of its range, an acceleration of speciation, i.e., to biological progress.
Many modern species are embraced by biological progress. For example, a hundred years ago, the border of the distribution of the hare in the north reached the line St. Petersburg - Kazan, and in the east - to the Ural River. At present, it has spread in the north - to Central Karelia and in the east - to Omsk. Now about 20 of its subspecies are known.
In nature, biological regression is also observed. It is characterized by features opposite to biological progress: a decrease in numbers; narrowing of the range; decrease in the number of species, populations. As a result, it often leads to the extinction of species.
Of the numerous branches of the most ancient amphibians, only those remained that led to the formation of modern classes of amphibians and reptiles. The ancient ferns and many other groups of plants and animals disappeared.
With the development of human civilization, the causes of biological progress and biological regression are increasingly associated with the changes that man makes to the landscapes of the Earth, breaking the links between living beings and the environment that have developed in the process of evolution.
Human activity is a powerful factor in the biological progress of some species, often harmful to him, and the biological regression of others, necessary and useful to him. Think of the emergence of many insect species resistant to pesticides, disease-causing microbes resistant to drugs, the proliferation of blue-green algae in wastewater. When sowing, man invades wildlife, destroys many wild populations over large areas, replacing them with a few artificial ones. The increased extermination of many species by man leads to their biological regression, which threatens them with extinction. Correlation of paths of evolution. The paths of evolution of large systematic groups (for example, types and classes) are very complex. Often in the development of these groups there is a successive change from one path of evolution to another. Of all the considered ways to achieve biological progress, aromorphoses are the rarest, raising one or another systematic group to a qualitatively new, higher level of development. Aromorphoses can be considered as turning points in the development of life. For groups that have undergone appropriate morphophysiological transformations, new opportunities open up in mastering the external environment.
Each aromorphosis is followed by many idioadaptations that ensure a more complete use of all available resources and the development of new habitats.
Birds and mammals have taken a dominant position among land animals. The acquisition of a constant body temperature (aromorphosis) allowed them to survive in glaciation conditions and penetrate far into cold countries, further evolution continued through idioadaptations, which led to the emergence of new species that mastered various habitats.
Parallelism. Convergence. Divergence. Aromorphosis. Idioadaptation. General degeneration. biological progress. biological regression.
1. What are the main characteristics of biological progress and biological regression. 2. List the main types of evolutionary changes, give their characteristics. 3. What are the main directions of evolution?
Summary of the chapter
The evolutionary idea is that living beings gradually change over time. Charles Darwin revealed the main driving forces evolution: heredity, variability and natural selection .
Heredity is the property of all organisms to preserve and transmit the properties of parents to offspring.
Variability is the property of organisms to acquire new traits. According to Charles Darwin, the variability of life forms corresponds to changes in the environmental conditions in which they live.
The presence of advanced properties allows organisms to be winners in the struggle for existence. Surviving, they have the advantage of passing advanced properties to their offspring. Darwin called this process natural selection.
Hereditary variability is constantly maintained by the appearance mutations and genetic recombination- a continuous process of gene shuffling during the formation of zygotes.
Scientists define microevolution as directed changes in the gene pool of a population, which is characterized by the frequency of occurrence of certain genes. Factors and mechanisms that control changes in the gene pool are studied by population genetics.
Natural selection destroys the less fit genotypes , resulting in an increase in the adaptability of populations to environmental conditions. Stabilizing selection is aimed at maintaining the already existing properties of organisms. driving selection contributes to changes in the properties of organisms. Disruptive selection leads to the emergence of polymorphism, which ensures the possibility of existence in various environmental conditions.
Reproductive isolation mechanisms (isolation mechanisms) lead to restrictions on the exchange of genetic material between populations. The fixation of reproductive isolation is supported by natural selection. A new species may arise as a result of the dismemberment of the range of a population or group of populations by physical barriers. This way of appearance of new species is called allopatric speciation. It is usually observed in the peripheral part of the range of the original species. The second way of speciation is called sympatric. In this case, the isolating mechanisms of one group of living beings from another may arise suddenly, as a result of chromosomal rearrangements in the genotype (for example, polyploidy).
The process of formation of larger systematic groups, genera, families, orders, etc. is called macroevolution. Macroevolution occurs over vast periods of time and therefore it is not available for direct study.
The same processes operate in macroevolution: the formation of phenotypic changes, the struggle for existence, natural selection, the extinction of the least adapted forms.
In the process of evolution, the following characteristic types of evolutionary changes are distinguished: parallelism, convergence and divergence. The main lines of evolution are: aromorphosis, idioadaptation, degeneration.
The paths of evolution of large systematic groups (for example, types and classes) are very complex. Often in the development of these groups there is a change from one line of evolution to another.
Question 1. What are the main directions of evolution of organisms.
There are three main directions of evolution, each of which leads to the prosperity of a group of organisms: 1) aromorphosis (morphophysiological progress); 2) idioadaptation; 3) general degeneration.
Question 2. Give examples of aromorphoses in plants.
An example of aromorphosis in angiosperms can serve:
Double fertilization.
The seeds lie inside the fruit, and the ovules are located inside the ovary.
Vascular formation.
Question 3. Consider figures 66 and 67. Give examples of idioadaptations in mammals.
Depending on the living conditions and lifestyle, the five-fingered limb of mammals undergoes numerous transformations. The forms of the limbs of representatives of the orders of rodents and lagomorphs are diverse. Similarly, the differences appearance and details of the structure of animals belonging to the orders of artiodactyls and corns are caused by the unequal conditions of their existence.
Question 5. Do you agree with the statement that general degeneration can contribute to biological prosperity and success? Justify your answer.
Question 6. What biological mechanism ensures the movement of groups of organisms in a particular evolutionary direction?
Natural selection and competition ensure the movement of groups of organisms in a particular evolutionary direction.
Question 7. Can it be argued that evolution can be both progressive and regressive? Justify the answer.
This statement is true, since evolution can proceed in two directions - progressive and regressive. The result of this movement is the adaptability of organisms to changing environmental conditions.
biological progress. In general, evolution is a process of development from lower to higher forms, from simple to complex. Academician A. N. Severtsov emphasized the existence of biological progress and biological regression in the history of the development of the organic world.
biological progress- it's a success specific type or systematic groups in the struggle for existence. The main signs of biological progress: a) an increase in the number of individuals of systematic groups; b) expansion of the range; c) the formation of a new population, variety, species.
Directions biological evolution. Academicians A.N. Severtsov and I.I. Shmalgauzen identified three directions of biological evolution leading to biological progress:
1. Aromorphosis (arogenesis).
2. Idioadaptation (allogenesis).
3. Degeneration (catagenesis).
1. Aromorphosis(Greek air o- "raise", morpha - "form"), or morphophysiological progress, the complication of the structure of individuals, the development of adaptations to life. Imagine the result of aromorphosis
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table 2
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Note. The materials given in the table are given in accordance with the epochs of development.
in the form of a table (Table 2). As a result of aromorphosis, new systematic groups are formed: types and classes.
Aromorphosis is formed on the basis hereditary variability and natural selection. An increase in the general activity of animals contributed to the appearance of complex changes in the respiratory organs: gills, lungs. The hearts of fish, birds and mammals have become more complex. All this contributed to the active life of animals, reduced their dependence on environmental conditions. Large systematic groups - type, class, order - were formed in the process of long evolution by aromorphosis. Aromorphosis is the main path to biological progress.
Evolution circulatory system- this is a complication from the tubular blood vessels of the lancelet to a two-, three-, four-chambered heart. In the evolution of mammals, several major aromorphoses can be distinguished: live birth, warm-bloodedness, progressive development of the circulatory system (formation of the large and small circles of blood circulation) and the brain (Fig. 32). The high general level of organization of mammals, achieved due to the listed aromorphic changes, allowed them to master all possible environments habitats (Arctic, Antarctica) and eventually led to the appearance higher primates and a person.
Rice. 32. Vertebrate aromorphosis
Plant aromorphosis:
1) transition from reproduction by spores to reproduction by seeds; 2) flower development; 3) the formation of a fruit from flowers; 4) reproduction in water and on land; 5) complication of the structure of plants.
Aromorphosis is the main path of evolution going in the direction of:
a) from unicellular to multicellular;
b) from a two-layer to a three-layer organism;
here lower levels to chordates.
2. Idioadaptation- allogenesis (Greek idios - "feature", Latin adaptatio - "adaptation"), i.e. adaptation to special conditions environment, useful in the struggle for existence, but without a fundamental restructuring of their biological organization. Since each type of organism is in certain places habitation, it develops an adaptation to these conditions. Examples of idioadaptation include the protective coloration of animals, glandular hairs, spines of plants, the flat shape of the body of rays and flounders (Fig. 33).
Rice. 33. Examples of idioadaptation: 1 - flounder; 2 - ramp
Depending on the lifestyle, the limbs of birds change: in an owl, the fingers are adapted to capture food (the same four fingers), in a woodpecker - for free movement along a tree trunk, in a stork, long limbs are adapted for movement in a swamp. To typical examples idioadaptation include: features in the structure of the limbs (mole, ungulates, floating), differences in the beak of birds (in predators - bent, marsh - very long, in nutcrackers - crossing, for splitting seeds). The protective coloration of various insects, fish, in plants, the adaptation of a flower for pollination, fruits and seeds for distribution. The lancelet and vertebrates had common ancestor, probably a skullless animal. The lancelet has survived to this day only thanks to its adaptation to the sandy bottom of the sea. Many species, having a similar level of organization, were able to acquire properties that allowed them to occupy completely different places in nature. For example, some species of fish live in fresh water, others - in salt, others - in deep layers reservoir.
Skat - cartilaginous fish, living in deep waters, moved to life at the bottom. In the process of evolution, with an increase in water pressure, the stingray acquired a flat body shape. Due to the slow movement, the stingray lost its tail and became available to enemies. Therefore, a protective coloration arose to match the color of the sandy bottom (sand, shells) and tail spikes. The dark bottom contributed to the formation of an electric organ. However, the main structural features characteristic of fish have not changed.
biological progress. Aromorphosis. Idioadaptation. Degeneration.
1. Biological progress is an increase in the fitness of organisms, leading to a high number of individuals in a systematic group, expansion of the range and division into subordinate systematic groups, adaptation of the population and species to the habitat.
1. How do you understand biological progress?
2. Name the main directions of the evolution of organisms.
1. What kind of biological evolution increases the level of organization of groups of organisms?
2. Give examples of aromorphosis.
1. What is idioadaptation?
2. Disassemble separately the structure of fish, frogs, lizards, birds, monkeys (Fig. 32).
Lab #5
Analysis of examples of aromorphosis, idioadaptation of plants and animals
Equipment: herbariums of spore plants (moss, plantain, conifers), angiosperms (any flowering plant); plants with thorns, hair (camel thorn, wild rose), drawings of the beak and legs of birds, animals with a protective (masking) color, stingray fish.
Tasks in progress.
1. Analyzing the main features of spore and angiosperms, understand the aromorphoses of plants.
2. Determine idioadaptation by plant thorn and glandular fibers.
3. Analyze examples of idioadaptation: the structure of the beak and legs of birds living in different environmental conditions.
4. To identify the causes of idioadaptation in the structure of the stingray fish.
Does the appearance of a layer of mesoderm in worms refer to aromorphosis? If so, which worms?
1. Analyze the phenomenon of aromorphosis in the structure of the heart of vertebrates.
2. What are the ways to achieve biological progress?
3. What complications have occurred in the structure of mammals with a progressive path of development?
4. What is the largest aromorphosis in plants?
5. Does it change biological level structure of organisms during idioadaptation?
6. Give examples of idioadaptation in plants.
