The concept of biological diversity

The living organisms of our planet have gone through a long and complex path of development. In the course of evolution, changes occurred in the external and internal structure of living organisms, the system of relationships between groups of organisms, between organisms and the environment changed. As a result of natural selection, living organisms developed qualities that helped them survive in a changing environment.

The result of such a long evolutionary path was the diversity of representatives of the wildlife of our planet. They have different life forms, belong to different kingdoms.

To date, it has been proven that all living organisms have a single origin. This statement is supported by the unity of the chemical composition of living organisms, their cellular structure.

But at the same time, some living organisms are very different from others. Due to the presence of these differences, the biological diversity of the living matter of our planet has been formed.

Definition 1

Biodiversity is the totality of all forms and varieties of the organization of the living matter of the biosphere.

Reasons for biodiversity

The reason for biological diversity is the ability of living organisms to adapt to certain environmental conditions - the ability to adapt.

As a result of interaction with various environmental factors on Earth, various ecological groups of living organisms have formed:

• thermophilic,
• cold-resistant,
• light-loving,
• moisture-loving,
• drought-resistant,
• etc.

In the process of competition for territory and food, living organisms led a different mode of existence - attached, freely moving, sedentary, migratory. Plants evolved life forms such as grasses, trees, and shrubs. With more detailed adaptation to environmental conditions, new species of plants, animals and microorganisms arose.

Summing up the above, we can conclude that the cause of biological diversity is the result of the constant interaction of living organisms and the environment. Recently, human activities have had a great impact on biodiversity.

Types of biodiversity

When considering biodiversity, attention is most often paid to such aspects as genetic, species and ecosystem.

Definition 2

genetic biodiversity is a set of gene pools of different populations of the same species.

To ensure genetic biodiversity, it is necessary to create an ecological network. This will make it possible to preserve representatives of the species not only in individual protected areas (in nature reserves), but also throughout the entire territory of the distribution of the species.

Definition 3

Species diversity is the totality of all species inhabiting a certain area.

Man's task is to preserve all existing species. After all, the loss of at least one species is an irreversible process. Protected areas are created to preserve species diversity.

Definition 4

Ecosystem biodiversity (landscape) is a collection of unique and typical forest, mountain, swamp, steppe, marine, river communities of living organisms.

Ecosystems are the main object of nature protection activities. They form the biogeographic feature of each region of our planet.

The concepts of succession and agrocenosis

Biogeocenoses are a self-regulating system. Therefore, in the process of development of biogeocenosis, its species diversity also changes.

Ecologists are sounding the alarm about the catastrophic reduction of biodiversity on our planet, associated with the activities of modern man, who, for the most part, living in the city, practically does not encounter nature, has no idea about its diversity and can only see it on TV. This gives him a sense of non-involvement of biodiversity in everyday life, but this is not so.

What is biodiversity?

The term biodiversity is commonly understood by scientists as the diversity of life on Earth - plants, animals, insects, fungi, bacteria and the ecosystems they form. In this concept, there is also a relationship that is present between them. Biodiversity can flow:

• at the level of genes, determines the variability of individuals of a certain species;
• at the species level, reflects the diversity of species (plants, animals, fungi, microorganisms);
• diversity, this includes differences between them and different ecological processes).

It should be borne in mind that all the above types of diversity are interconnected. Many ecosystems and different landscapes create conditions for the emergence of new species, genetic diversity makes it possible to change within one species. The reduction of biodiversity indicates certain violations of these processes.

Currently, environmentalists are sounding the alarm due to the fact that human beings are violating living conditions, ecological processes, a person is creating new types of plants and animals at the gene level. How this will affect future life on Earth is unknown. After all, everything in nature is interconnected. This is the so-called "butterfly effect". The science fiction writer Ray Bradbury told the world about him in his story "Thunder Came" back in the middle of the last century.

Impossibility of life without biodiversity

The most valuable and important thing that exists on earth is biological diversity. Whether we know about it or not, but our whole life depends on the biological wealth of the earth, since animals and vegetation give it to us. Thanks to plants, we get enough oxygen, and materials based on them give us not only food, but also wood, paper, fabrics.

In our technogenic age, a huge amount of energy is needed, obtained by burning fuel, which is produced from oil formed as a result of the decomposition of the remains of many organisms and plants. Human life without biological diversity is impossible.

Coming to the store, we buy food packaged in bags, thinking little about where it comes from. The life of the majority of the population takes place in an artificial environment, which is made up of asphalt, concrete, metal and artificial materials, but this does not mean that the consequences of biodiversity reduction will bypass mankind.

Life on Earth and its diversity

The history of planet Earth suggests that at various times it was inhabited by many living organisms, most of which, as a result of evolution, died out and gave way to new species. Conditions and reasons contributed to this, but even during periods of natural stagnation there was no reduction in biodiversity, diversity increased.

Nature is arranged in such a way that everything in it is in interaction. No species of living organisms can live and develop in a closed environment. This was shown by numerous experiments on the creation of isolated biosystems that suffered a complete collapse.

Modern scientists have described and studied 1.4 million species of living organisms, but according to calculations, there are from 5 to 30 million species on Earth that live and develop depending on conditions. This happens naturally. Living organisms populated the entire planet. They live in water, air, and land. They can be found in the desert and in the Northern and Southern belts. Nature provides everything necessary to continue life on Earth.

With the help of living organisms, the nitrogen and carbon cycle takes place, which, in turn, supports the renewal and processing of natural resources. The environment favorable for life, which the Earth's atmosphere creates, is also regulated by living organisms.

What contributes to the reduction of biodiversity?

First of all, the reduction of forest areas. As mentioned above, plants play a very important role in the life of the planet. The taiga and the jungle are called the lungs of the planet, thanks to them it receives a sufficient amount of oxygen. In addition, more than half of the species of living organisms exist in the jungle, which occupies only 6% of the earth's surface. They are called the genetic fund accumulated over 100 million years of evolution on Earth. Its loss will be irreplaceable and can lead the planet to a complete ecological catastrophe.

The reasons for the decline in biodiversity are the activities of a person who transforms the planet in order to meet their own, not always reasonably increased, needs. Uncontrolled cutting of taiga and jungles leads to the disappearance of many species of life, even unexplored and not described by man, to disruption of ecosystems and water balance.

This is facilitated by deforestation and burning, the harvesting of various types of plants and fishing carried out in predatory sizes, the use of pesticides, the drainage of swamps, the death of coral reefs and the cutting down of mangroves, an increase in the number of agricultural lands and the area of ​​\u200b\u200bsettlements.

It is clear that the development of technology, technical progress cannot be stopped. But it is necessary to take measures to solve the environmental problems of biodiversity reduction.

International Convention on Biological Diversity

For this purpose, the "Convention on Biological Diversity" was adopted, which was signed by 181 countries, whose governments assumed obligations to preserve it in their countries, pledged to act jointly with other states and share the benefits of using genetic resources.

But this has not prevented the reduction of biodiversity on the planet. The ecological situation on Earth is becoming more threatening than ever. But there is hope that the common sense that God has given to man will prevail.

Evolution is the engine of life

The engine of life forward is evolution, as a result of which some species die out and new ones appear. All modern living beings have replaced the extinct ones, and, as scientists have calculated, out of the whole variety of species that existed on Earth, their current number is only 1% of their total number.

The extinction of species is a natural moment of evolution, but the current rate of biodiversity reduction on the planet is rampant, there is a violation of natural self-regulation and this has become one of the most important environmental problems of mankind.

The role of the species in the biosphere

The knowledge of mankind about the role played by representatives of one species or another in the biosphere is negligible. But scientists know for certain that each species has a certain meaning in nature. The disappearance of one species and the inability to replace it with a new one can lead to a chain reaction that will lead to the extinction of man.

Necessary actions

First of all, humanity should try to save the rainforests. Thus, leaving the opportunity to save some species of living beings and plants from extinction. The preservation of the jungle will lead to climate stabilization.

The jungle is a direct source of the richest genetic material, a treasury of various types of living beings. In addition, it is a source of plants, on the basis of which a person creates unique medicines. By moistening the atmosphere, tropical forests prevent global climate change.

Biodiversity as a key factor in sustainable development

Biological diversity is the diversity of all forms of living organisms and the systems of which these organisms are part. The concept of biological diversity refers to different levels of organization of living things - molecular-genetic, population-species, taxonomic (from "taxonomy" - systematics) and cenotic (from "cenosis" - community). Each subsequent of these levels includes the previous one.
Biological diversity forms the biota of the Earth, represented both by the totality of organisms and species, and by the structure of their distribution among communities (biocenoses) and by the communities themselves as the main structural units of the biosphere.

Importance of biological diversity

Biological diversity was formed as a result of the interaction between the biosphere and the geographic envelopes of the Earth - the hydrosphere, atmosphere and the earth's crust (lithosphere), the composition of which, in turn, is largely determined by the biota. It was the biota that at one time caused the transition of a reducing atmosphere into an oxidizing one, which gave impetus to the evolutionary process and the emergence of new forms of life.

As life conquered the planet, living beings became increasingly important as a factor in the transformation of matter and energy. The effectiveness of these processes, without which life on Earth is already unthinkable, is determined by biological diversity - the functional specialization of various species and the distribution of their roles in communities.

The stability factors of biological communities themselves (as well as any other complex systems) are duplication (in this case duplication of ecological niches occupied by different organisms) and redundancy of structural elements. These factors in natural conditions are provided by biological diversity - as a rule, the removal of any one species does not lead to the destruction of the ecosystem, because functional relationships are maintained at the expense of other species.

Biological diversity also determines such an important property of life as the maintenance of certain climatic environmental conditions suitable for life. First of all - the temperature range that ensures the stay of water in a liquid state. According to modern cosmogonic concepts, there are no physical barriers between the climatic conditions of the Earth and neighboring planets - Mars and Venus, where life is impossible. The transition of the Earth's climate to the climate of any of these planets can take place in a fairly short period of time - about 10 thousand years. However, for almost 4 billion years of the history of life on Earth, this has not happened due to the fact that albedo, the greenhouse effect and other important characteristics of the climate are under the control of the global biota. In support of this concept, we present three typical examples.

Emissions of inorganic carbon from the earth's interior into the atmosphere are compensated by the deposition of this element in the composition of organic compounds, in sedimentary rocks, so that the CO 2 content in the atmosphere remains at a relatively constant level for hundreds of millions of years.

The quantitative ratio in the ocean of carbon, nitrogen, phosphorus and oxygen atoms that make up various compounds coincides with the ratio of these elements in living matter, which indicates that their concentration is due to the activity of biota.

Biota also plays a dominant role in the water cycle on land: 2/3 of precipitation is determined by transpiration - the evaporation of water from the surface of plants.

Finally, we should not forget that living organisms provide us with food and clothing, building materials, medicinal substances and, importantly, spiritual food. Species of wild plants and animals are an exhaustible, irreplaceable resource, a repository of an invaluable genetic fund, of all the possibilities of using which we sometimes do not even suspect.

In the second half of the XX century. Humanity is faced with a contradiction between growing economic needs and the inability of the biosphere to meet these needs. The riches of nature, the possibilities of its self-healing turned out to be not unlimited.

The elimination of this contradiction is possible only within the framework of the so-called sustainable development human society based on the satisfaction of our economic needs within the economic capacity of the biosphere, those. within limits that do not entail irreversible changes in the natural environment. Otherwise, the reduction of biological diversity can really develop into an ecological catastrophe that threatens our very existence on Earth.

What we know about biotic regulation of the environment allows us to conclude that this limit has already been surpassed, but irreversible changes in the biosphere have not yet occurred, and humanity retains a chance to return to the area of ​​permissible influences.

To reduce the degree of pressure on nature and continue to comply with the permissible level is the only way for us to survive. At the same time, we are talking not so much about reducing environmental pollution, but about preserving natural ecosystems, preserving biological diversity as the main regulator of the sustainability of the biosphere. After all, our civilization, using a huge number of technologies that destroy ecosystems, has not offered, in fact, anything that could replace natural regulatory processes. And it is obvious that humanity will not have time to learn how to somehow regulate the state of the environment by technical means in the time that we have left before the start of catastrophic changes in the biosphere. So the only chance to eliminate a more than real threat to the vital interests of future generations is to clear the way for the stabilizing action of natural forces themselves.

State of biological diversity on the planet and in Russia

Currently, the biological diversity of the planet is impoverished due to the following reasons.

1. Direct destruction of ecological systems - uprooting, burning and cutting down forests, plowing steppes, draining swamps and floodplain reservoirs, as well as building up natural biotopes with settlements, industrial enterprises, laying transport highways ... Anthroposystems arise in place of natural ecosystems. With such an impact, both ecosystem and species diversity are simultaneously destroyed.

2. Transformation of original ecosystems under the influence of anthropogenic influences - changes in forest types under the influence of felling (the emergence of anthropogenic forest successions) and silvicultural work, artificial afforestation of open spaces, the creation of semi-natural agrolandscapes (agrobiocenoses), an increase in pastures depleted under the influence of overgrazing ... Transformed ecosystems are usually depleted in terms of species.

To be continued

Biodiversity

Signed in June 1992 in Rio de Janeiro, the International Convention on Biological Diversity can be seen mainly as an expression of general concern about the loss of what cannot be restored - species of living beings, each of which occupies a certain place in the structure of the biosphere. Will a united humanity be able to preserve biodiversity? This largely depends on the attention of historical processes and the current factors that have influenced biological diversity as we know it, or, more precisely, we know it to a small extent.

We don't know how many species there are. In the rainforest canopy alone, there can be up to 30 million, although most researchers accept a more conservative figure of 5-6 million. There is only one way to save them - by protecting the tropical forest as an ecosystem from clear-cutting and pollution. In other words, in order to preserve species diversity, it is necessary first of all to take care of the diversity of a higher level - ecosystems. At this level, tundras and polar deserts deserve no less attention than tropical forests, with which they are comparable in spatial parameters as structural subdivisions of the biosphere, although they are much poorer in species.

Biological diversity (BD) is a variety of forms and processes in the organic world, manifested at the molecular genetic, population, taxonomic and cenotic levels of the organization of the living. Although the levels of organization are named here in their traditional bottom-up sequence (each subsequent level includes the previous ones), this order of consideration does little to understand the nature of BR. If we are interested in the reasons for the emergence of BR (according to religious beliefs, BR arose as a result of a creative act, the logic of which should also be available to a reasonable being), then it is better to move from top to bottom, starting with the biosphere - the earth's shell containing organisms and their metabolic products. The biosphere is superimposed on the physical shells of the Earth - the earth's crust, hydrosphere and atmosphere, the composition of which is largely determined by the biogenic circulation of substances.

Each of these shells, in turn, is heterogeneous in physical properties and chemical composition in the direction of gravity and rotational forces, which determine the division into the troposphere and stratosphere, oceans, marginal seas and inland water bodies, continents with their geomorphological heterogeneities, etc. Heterogeneity of conditions It is also created by the uneven distribution of incoming solar energy over the earth's surface. The latitudinal climatic zonality on the continents is complemented by climatic vectors directed from the coast inland. A regular change in conditions in terms of height above sea level and depth creates a vertical zonality, which is somewhat similar to latitudinal zonality. Life is superimposed on all these heterogeneities, forming a continuous film that does not break even in deserts.

Continuous living cover is the result of long evolution. Life arose at least 3.5 billion years ago, but for about 6/7 of this time, the land remained practically lifeless, as did the ocean depths. The expansion of life was carried out by adapting to different conditions of existence, differentiation of life forms, each of which, within its habitats, is most efficient in the use of natural resources (you can try to replace all diversity with one species, as modern man does, in essence, but the efficiency resources of the biosphere will sharply decrease as a result).

Conditions changed not only in space, but also in many respects similarly in time. Some forms of life have proven to be more adaptable to change than others. Life was interrupted in separate zones, but, at least in the last 600 million years, there were constantly forms that could survive the crisis and fill the gaps that had formed (remains of more tree organisms are not numerous, and we are not sure that during the Precambrian history life did not interrupted). Thus, BR ensures the continuity of life in time.

As life covered the surface of the planet with a continuous film, the organisms themselves increasingly acquired the importance of the main factor in the formation of living space, the functional structure of the biosphere, associated with the biogenic transformation of matter and energy carried out within its boundaries, the effectiveness of which is ensured by the distribution of roles between organisms, their functional specialization. . Each functional cell of the biosphere - an ecosystem - is a local set of organisms interacting in the process of biogenic circulation and components of their environment. The spatial expression of an ecosystem can be a landscape, its facies (in this case, they speak of a biogeocenosis, which, according to V.N. Sukachev, includes a geological substrate, soil, vegetation, animal and microbial populations), any component of the landscape (water body, soil, plant community) or a single organism with its external internal symbionts.

The functional space of an ecosystem (multidimensional, in contrast to the physical one) is subdivided into ecological niches corresponding to the distribution of roles between organisms. Each niche has its own life form, a kind of role that determines the main morphophysiological features of organisms and depends on them in feedback. The formation of an ecological niche is a mutual process in which the organisms themselves play an active role. In this sense, niches do not exist apart from life forms. Nevertheless, the predetermination of the ecosystem structure, associated with its functional purpose, makes it possible to recognize "empty niches" that must be filled in order for the structure to be preserved.

Thus, biological diversity is necessary to preserve the functional structure of the biosphere and its constituent ecosystems.

A stable combination of functionally interconnected life forms forms a biotic community (biocenosis), the composition of which is the more diverse, the more complex the structure of the ecosystem, and this latter depends mainly on the stability of the processes occurring in the ecosystem. So, in the tropics, the diversity is higher, since photosynthesis is not interrupted during the year.

Another important function of the BR is associated with the development and restoration of the community - reparation. Species perform different roles in the course of autogenetic succession - a change in developmental stages from pioneer to climax. Pioneer species are undemanding in terms of quality and sustainability of the environment and have a high reproductive potential. Stabilizing the environment, they gradually give way to more competitive species. This process goes to the final phase (climax), which is capable of holding the territory for a long time, being in a state of dynamic equilibrium. Since a variety of external influences constantly disrupt succession, monoclimax most often remains a theoretical possibility. Stages of development are not completely replaced, but coexist in complex successional systems, providing them with the opportunity to recover from destructive impacts. The recovery function is usually performed by rapidly breeding pioneer species.

It would be an exaggeration to claim that we can accurately determine the functional purpose of each species in any of the many ecosystems. The removal of a species also does not always lead to their destruction. Much depends on the complexity of the ecosystem (in Arctic communities with a relatively simple trophic structure, the share of each species is much higher than in the tropics), its succession and evolutionary stage of development, which determines the overlap (duplication) of ecological niches and the redundancy of structural elements. At the same time, duplication and redundancy in systems theory are considered as stability factors, i.e., they have a functional meaning.

All of the above allows us to conclude that the random element in the BR does not play a significant role. BR is functional. Each of its components is formed by the system in which it is included, and in turn, according to the feedback principle, determines the features of its structure.

In general, BR reflects the spatio-temporal and functional structure of the biosphere, providing: 1) the continuity of the living cover of the planet and the development of life in time, 2) the efficiency of biogenic processes in the ecosystem, 3) the maintenance of dynamic balance and the restoration of communities.

These appointments determine the structure of the BR at all hierarchical levels of its organization.

^ Structure of biological diversity

The genetic material in most organisms is contained in huge molecules of DNA and RNA, filamentous polynucleotides that can look like a ring chromosome or a set of linear chromosomes, which are extremely diverse in terms of the total content of DNA, number, shape, development of various types of heterochromatin. and also by the types of restructurings in which they participate. All this creates a variety of genomes as complex systems that make up - in higher organisms - from tens of thousands of discrete genetic elements, or genes. Their discreteness is structural in nature (for example, unique or repetitive nucleotide sequences) or expressed functionally, as in protein-coding, reproducible as a whole, co-managed, involved in cross-exchange between paired chromosomes, and, finally, moving through the genome elements. When molecular mechanisms were not understood, the idea of ​​a gene was abstract and endowed with all these functions, but now it is known that they are performed by structurally different genetic particles that make up a variety of gene types. As a result of changes in the nucleotide composition, or mutations, similar sections of paired chromosomes have a different structure. Such sites-chromosomal loci, known in several states, are called polymorphic. Genetic polymorphism is transformed into protein polymorphism, which is studied by molecular genetic methods, and, ultimately, into the genetic diversity of organisms. At these derived levels, the diversity of genes appears in an indirect form, since traits are determined by the genetic system, and not by individual genes.

N. I. Vavilov showed on extensive material that the diversity of hereditary characters in closely related species is repeated with such accuracy that it is possible to predict the existence of a variant not yet found in nature. Thus, the orderliness of genetic variability (contrary to the ideas about the unpredictability of mutations) was revealed, in which the properties of the genome as a system are manifested. This fundamental generalization, formulated as the law of homological series, underlies the study of the BR structure.

The transfer of hereditary information from one generation to another is carried out in the process of reproduction of organisms, which can be asexual, sexual, in the form of alternation of asexual and sexual generations. Superimposed on this diversity are differences in the mechanisms of sex determination, sex separation, etc. Suffice it to think of fish species that consist of some females (reproduction is stimulated by males of other species) or the ability of females to turn into males, if there are not enough of them, to imagine diversity. reproduction processes in vertebrates, not to mention organisms such as fungi, where it is many times higher.

Organisms involved in reproduction constitute the reproductive resources of a species, which are structured according to the diversity of reproductive processes. The units of the reproduction system are demo-local groupings of interbreeding individuals and populations - larger groupings within a landscape or ecosystem. Accordingly, geographical and coenotic populations are distinguished, although their boundaries may coincide.

In the process of reproduction, recombination of genes takes place, which, as it were, belong to the population as a whole, constituting its gene pool (the gene pool is also spoken of in a broader sense as the totality of fauna or flora genes; this is partly justified, since at least episodic gene exchange is possible during hybridization or transfer of genetic material by microorganisms). The unity of a population, however, is ensured not only by a common gene pool, but also by entry into geographic or biological systems of a higher level.

Populations of neighboring landscapes or ecosystems always show certain differences, although they may be so close that taxonomists consider them to be the same species. In essence, a species is a set of populations of a number of historically interconnected landscape and (or) cenotic complexes. The integrity of a species as a system is due to the historical community of its constituent populations, the flow of genes between them, as well as their adaptive similarity due to close living conditions and coenotic functions. The latter factors are also effective in relation to asexual organisms, determining the universal significance of a species as the main unit of biological diversity (the often encountered hypertrophied idea of ​​sexual gene transfer as the most significant criterion for a biological species makes us see it as a category peculiar exclusively to dioecious organisms, which contradicts taxonomic practice).

The properties of a species are determined, as we have already noted, by that part of the ecological space that it steadily occupies, i.e. ecological niche. At the early stages of the development of the biological community, there is a significant overlap of ecological niches, but in the established coenotic system, species, as a rule, occupy rather isolated niches, however, it is possible to move from one niche to another in the growth sling (for example, in attached forms with mobile larvae) , entry into various communities in some cases as a dominant, in others - a secondary species. There are certain disagreements among specialists regarding the nature of biotic communities - either random collections of species that have found suitable conditions for themselves, or integral systems like organisms. These extreme points of view, most likely, reflect the diversity of communities that are completely unequal in their systemic properties. Also, species are sensitive to their coenotic environment to varying degrees, from independent (conditionally, since they belong to communities of higher ranks) to “true”, according to which associations, unions and classes are distinguished. This classificatory approach was developed in Central Europe and is now widely accepted. A rougher "physiognomic" classification according to the dominant species is adopted in the northern countries, where relatively homogeneous forest formations still occupy vast areas. Within landscape-climatic zones, groups of characteristic formations form the biomes of tundra, taiga forests, steppes, etc.) - the largest landscape-coenotic subdivisions of the biosphere.

^ Evolution of biological diversity

BR develops into a process of interaction between the biosphere and the physical shells of the Earth, on which it is superimposed. The movement of the earth's crust and climatic events cause adaptive changes in the macrostructure of the biosphere. For example, a glacial climate is characterized by a higher diversity of biomes than a non-glacial one. Not only polar deserts, but also tropical rainforests owe their existence to the atmospheric circulation system, which is formed under the influence of polar ice (see above). The structure of biomes, in turn, reflects the contrast of relief and climate, the diversity of geological substrates and soils - the heterogeneity of the environment as a whole. The species diversity of the communities that make up them depends on the fragmentation of the division of the ecological space, and this latter depends on the stability of conditions. In general, the number of species is s==g – py, where a is the diversity of species in communities, p is the diversity of communities, and y is the diversity of biomes. These components change with a certain frequency, rebuilding the entire BR system. For example, in the Mesozoic (glacier-free climate), the diversity of plants approximately corresponds to the modern one in similar formations of hard-leaved shrubs and summer-green forests, but the total number of species is about half that of the modern one due to the low diversity.

Genetic diversity in turn changes as a function of the adaptive strategy of the species. The fundamental property of a population is that, theoretically, during its reproduction, the frequencies of genes and genotypes are preserved from generation to generation (the Hardy-Weinberg rule), changing only under the influence of mutations, gene drift and natural selection. Variants of the structure of genetic loci that arise as a result of mutations - alleles - often do not have an adaptive effect and constitute a neutral part of polymorphism, subject to random changes - gene drift, and not directed selection - hence the model of "non-Darwinian" evolution.

Although the evolution of population diversity is always the result of drift and selection, their relationship depends on the state of ecosystems. If the ecosystem structure is disturbed, stabilizing selection is weakened, then evolution acquires an incoherent character: genetic diversity increases due to mutagenesis and drift without a corresponding increase in species diversity. Ecosystem stabilization directs the strategy of populations towards a more efficient use of resources. At the same time, the heterogeneity (“coarse-grain”) of the environment, which is more pronounced, becomes a factor in the selection of genotypes that are most adapted to the “grain” of the landscape-coenotic mosaic. At the same time, neutral polymorphism acquires an adaptive value, the ratio of drift and selection changes in favor of the latter. The progressive differentiation of demes becomes the basis for the fragmentation of species. Evolving steadily over millennia, these processes create exceptionally high species diversity.

The system, thus, directs the evolution of the organisms included in it (we note, in order to avoid misunderstandings, that there are no organisms that are not included in the coenotic systems: even the so-called coenophobic groups that disrupt the development of the community are included in systems of a higher rank).

The end-to-end evolutionary trend is one of increasing diversity, interrupted by sharp declines as a result of mass extinctions of species (about half at the end of the dinosaur era, 65 million years ago). The frequency of extinction coincides with the activation of geological processes (movement

Earth's crust, volcanism) and climatic changes, pointing to a common cause.

In the past, J. Cuvier explained such crises by the direct destruction of species as a result of marine transgressions and other catastrophes. Charles Darwin and his followers did not attribute crises at all, attributing them to the incompleteness of the geological Chronicle. Crises are now beyond doubt; moreover, we are experiencing one of them. A general explanation of crises is given by the ecosystem theory of evolution (see above), according to the second, the reduction in diversity occurs due to the stability of the environment, which determines the trend towards

simplifying the structure of ecosystems (some species are redundant),

interruption of successions (types of the final-climax - stages are doomed to extinction) and

an increase in the minimum size of the population (in a stable environment, a small number of individuals ensures reproduction, a “dense packing” of species is possible, but in a crisis, a small population that is incapable of rapid growth can easily disappear).

These patterns are also valid for the anthropogenic crisis of our days.

^ Human Impact on Biodiversity

The direct ancestors of man appeared about 4.4 million years ago, at the beginning of the Gilbert paleomagnetic epoch, marked by the expansion of glaciation in the Antarctic, aridization and the spread of herbaceous vegetation in low latitudes. The habitat, borderline between the tropical forest and the savannah, the relatively weak specialization of teeth, the anatomy of the limbs, adapted both to movement in open areas and to tree acrobatics, testify to the wide ecological louse of the African Australopithecus, the oldest representative of this group. In the future, evolution enters a coherent phase, and species diversity increases. Two lines of adaptive radiation - graceful and massive Australopithecus - developed along the path of food specialization, in the third line - Homo labilis - at the level of 2.5 million years, signs of tool activity appeared as a prerequisite for expanding the food niche.

The latter turned out to be more promising in the unstable conditions of the Ice Age, the crisis phases of which correspond to the wide distribution of polymorphic species of Homo erectus and later Homo sapiens with a discrepancy between high genetic and low species diversity characteristic of incoherent evolution. Each of them

Then it entered the phase of subspecific differentiation. About 30 thousand years ago, the specialized Neanderthal subspecies of the “reasonable” was supplanted by the nominative subspecies, the fragmentation of which was already proceeding along the line of cultural rather than biological evolution. Wide adaptive capabilities provided him with relative independence from local ecosystems, which has recently developed into cenophobia. As we have already noted, cenophobia is possible only up to a certain level of the hierarchy of natural systems. Cenophobia towards the biosphere as a whole dooms the species to self-destruction.

A person has an impact on all factors of BD - spatio-temporal heterogeneity of conditions, the structure of ecosystems and their stability. Disturbance of the climax community as a result of logging or fires can give some increase in species diversity due to pioneer and succession species. Spatial heterogeneity in some cases increases (for example, there is a dismemberment of vast forest tracts, accompanied by a certain increase in species diversity). More often, a person creates more homogeneous conditions. This is expressed in the leveling of the relief (in urbanized areas), deforestation, plowing up steppes, draining swamps, introducing alien species that are crowding out native ones, etc.

The influence of man on temporal factors is expressed in the multiple acceleration of natural processes, such as desertification or drying up of inland seas (for example, the Aral Sea, which in the past has repeatedly dried up without human participation). Human impact on the global climate destabilizes biospheric rhythms and creates a general prerequisite for simplifying the structure of terrestrial and aquatic ecosystems, and, consequently, for the loss of BR.

Over the past two decades, forests have been reduced by almost 200 million hectares, and now the damage is about 1% of the remaining area per year. These losses are distributed very unevenly: the greatest damage was caused to the tropical forests of Central America, Madagascar, Southeast Asia, but also in the temperate zone such forest formations as redwood in North America and China (metasequoia), Manchurian black fir forests in Primorye, etc. are on the verge of extinction. Almost no undisturbed habitats remain within the steppe biome. In the United States, more than half of the wetlands have been lost, in Chad, Cameroon, Nigeria, India, Bangladesh, Thailand, Vietnam, and New Zealand - more than 80%.

The loss of species due to habitat disturbance is difficult to assess, since the methods of accounting for species diversity are very imperfect. Assuming a "moderate" insect diversity estimate of 5 million species for tropical forests and a number of species proportional to the fourth power of area, the loss due to deforestation is 15,000 per year. Actual losses may differ significantly from the calculated ones. For example, in the Caribbean, no more than 1% of primary forests remain, but the diversity of native bird species has declined by only 11%, as many species have survived in secondary forests. Even more problematic is the assessment of the reduction in the BD of soil biota, which reaches 1000 species of invertebrates per sq. km. m. The loss of soil cover as a result of erosion is estimated in total at 6 million hectares per year - about 6 * 107 species can live in this area.

Probably, the most significant loss of species diversity is associated with the economic development and pollution of ecosystems, which are characterized by a particularly high level of endemism. These include hard-leaved formations of the Mediterranean and Kalekoy province in southern Africa (6000 endemic species), as well as rift lakes (Baikal - about 1500 endemics, Malawi - more than 500).

According to (McNeely, 1992), the loss of species diversity by groups since 1600 is:

Disappeared under threat

Higher plants 384 species (0.15%) 18699 (7.4%)

Pisces 23 -»- (0.12%) 320 (1.6%)

Amphibians 2-»-(0.05%) 48(1.1%)

Reptiles 21 -»- (0.33%) 1355 (21.5%)

Birds 113-»- (1.23%) 924 (10.0%)

Mammals 83 -»- (1.99%) 414 (10.0%)

Violation of the structure and function of ecosystems is associated with their use as raw materials, recreational and deposit (for waste disposal) resources, and raw and deposit use can give directly opposite results. Thus, overgrazing, removal of canopy-forming trees or game animals disrupt the trophic structure and often return the ecosystem to the early stages of development, delaying succession. At the same time, the flow of organic pollutants into water bodies accelerates succession, passing the ecosystem through a eutrophic state to a hypertrophic one.

The size of the human population does not depend much on the size of the exterminated species, so the feedback in the "predator-prey" system is violated, and a person gets the opportunity to completely exterminate one or another type of prey. In addition, in his role as a superpredator, a person exterminates not the weak and sick, but, on the contrary, the most complete individuals (this also applies to the practice of loggers to cut down the most powerful trees in the first place).

However, indirect damage from impacts that disrupt the balanced relationships and processes in ecosystems and thereby change the direction of species evolution is of greatest importance. Evolutionary changes occur as a result of mutagenesis, genetic drift and natural selection. Radiation and chemical pollution have a mutagenic effect. Withdrawal of biological resources - a significant part of natural populations - turns into a gene drift factor, forcing natural population fluctuations, loss of genetic diversity and, giving an advantage to genotypes with accelerated puberty and high reproductive potential (because of this, indiscriminate removal usually leads to accelerated puberty and shredding ). The direction of natural selection can change under the influence of a variety of biological, chemical. physical (noise, electromagnetic, etc.) pollution. Biological contamination - the deliberate or accidental introduction of alien species and biotechnological products (including laboratory strains of microorganisms, artificial hybrids and transgenic organisms) - is a common factor in the loss of natural BR. The most famous examples are the introduction of placentals into Australia (in fact, reintroduction, since they lived on this continent many millions of years ago), elodea into the reservoirs of Eurasia, ctenophores into the Sea of ​​Azov, amphipods Corophium cnrvispinHm into the Rhine from the Ponto-Caspian region (from the first appearance in In 1987, the number of this species increased to 100 thousand individuals per 1 sq.m., competing with local species of zoobenthos, which serve as food for commercial fish and waterfowl). Biological pollution is undoubtedly facilitated by changes in habitats as a result of physical and chemical impacts (increase in temperature and salinity, eutrophication in the case of the introduction of amphipod-thermophilic filter feeders),

In some cases, exposure causes a chain reaction with far-reaching consequences. For example, the entry of eutrophic substances into coastal waters from the continent and from mari culture causes dinoflaellate blooms, secondary pollution with toxic substances, the death of cetaceans, and an increase in the solubility of carbonates, the death of corals and other skeletal forms of benthos. Acid-forming pollution of water bodies, in addition to a direct impact on respiration (deposition of aluminum on the gills) and the reproductive function of amphibian fish, threatens the extinction of many species of aquatic vertebrates and semiaquatic birds due to a decrease in the biomass of larvae of stoneflies, mayflies, and chironomids.

The same factors change the ratio of genotypes in animal and plant populations, giving an advantage to those who are more resistant to various types of stress.

Pollution also becomes a powerful factor in natural selection. A classic example is the increase in the frequency of the melanistic form of Biston betularia butterflies in industrial areas, which was tried to be explained by the fact that on soot-covered trunks they are less noticeable to birds than light forms. This now textbook explanation seems naive, since melanistic forms appear to be more resistant to pollution in many species, including domestic cats and humans. This example warns against simplistic notions of human impact on BR.

^ Biodiversity Conservation

In ancient times, as we have already noted, totemism and the religious ideas that grew out of it contributed to the preservation of individual species and their habitats. We owe the preservation of such relics as ginkgo mainly to the religious rituals of the eastern peoples. In North America, European Colonists took over from local tribes their normative attitude towards nature, while in European feudal countries nature was preserved mainly as royal hunting grounds and parks, with which the aristocracy protected itself from too close contact with the common people.

In early democracies, moral and aesthetic motives were supplanted by economic ones, which often came into conflict with the preservation of BR. The utilitarian attitude to nature acquired especially ugly forms in totalitarian countries. P. A. Manteifel, expressing the official attitude, wrote in 1934: “These groups (of animals) have developed without the influence (will) of man and do not correspond in the majority to the economic effect that could be obtained with a rational change in zoological boundaries and communities, and therefore we put forward the question of the reconstruction of the fauna, where, in particular, the artificial migration of animals should take a prominent place.

Nevertheless, the new aristocracy - the party leadership and persons close to it - also needed protected hunting grounds, which were called hunting reserves.

In the 1960s, the reserves underwent a two-fold reduction due to the extensive development of the economy. In addition, the allotment of huge areas for monoculture had an extremely unfavorable effect on the state of the BR. In the early 1980s, to fulfill the "food program", roadsides, borders and inconveniences were plowed, depriving wild species of their last refuges in developed areas.

Unfortunately, these trends were further developed during the period of perestroika in connection with the transfer of waste land to farmers and the development of private enterprise in the conditions of legislative chaos. Land squatting for vegetable gardens, deforestation in green belts around cities, illegal extraction of rare species and free sale of biological resources have become common practice. The reserves have never been very popular on the ground and with the weakening of control they are subject to increasing pressure from economic structures and poachers. The development of international tourism is damaging territories that were previously protected as sensitive. These include military training grounds and border lands (in Germany, the 600x5 km exclusion zone has turned into a kind of reserve over the years of confrontation, which is now trampled down by crowds of tourists).

At the same time, there is reason to hope for an improvement in the situation (and, in particular, the transformation of former regime areas into nature reserves) due to the universal recognition of the priority of conservation of the BR. The immediate task is to develop and strengthen national programs. Let us note some fundamental points arising in this connection. Inventory and protection of biological diversity. Identification of the species structure in many cases is necessary for the organization of protection. For example, the New Zealand tuatara (tuatara), the only representative of the oldest group of beak-headed reptiles, has been protected since 1895, but only recently it has become clear that there are two species of tuatara with subspecies, one of the species, S-guntheri and a subspecies of the other, S.punctata reischeki were on the verge of extinction, and ten out of forty populations have already disappeared; there is still a lot of work ahead of traditional systematics in the field of BR conservation.

At the same time, the idea quite often expressed that in order to preserve it is necessary, first of all, to inventory all taxonomic diversity, has a somewhat demagogic connotation. There can be no question of describing all the multimillion-dollar diversity of species in the foreseeable future. Species disappear without ever receiving the attention of a taxonomist. A more realistic approach is to develop a sufficiently detailed syntaxonomic classification of communities and organize in situ protection on this basis. The protection of a top-level system, to a certain extent, ensures the preservation of its components, some of which we do not know or know in the most general terms (but at least we do not exclude the possibility of learning in the future). In the following sections, we will consider some of the principles for organizing protection on a syntaxonomic basis to cover all or most of the taxonomic diversity.

Combining human rights with animal rights. Recognition of animal rights does not mean rejection of their use. In the end, people are also used legally. It cannot be denied that it is fair that a man has more rights than an animal, just as an adult has more rights than a child. However, without falling into ecological terrorism, which is mostly provocative, it should still be recognized that reasonable use has nothing to do with killing for pleasure or on a whim, as well as with cruel experimentation, which, moreover, is mostly senseless, according to

BIOLOGICAL DIVERSITY (biodiversity), a concept that came into wide use in the 1980s in the fields of fundamental and applied biology, the exploitation of biological resources, policy in connection with the strengthening of the environmental movement, the awareness of the uniqueness of each biological species and the need to preserve all the diversity of life for sustainable development biosphere and human society. This was reflected in the International Convention on Biological Diversity adopted in Rio de Janeiro in 1992 (signed by Russia in 1995). In the scientific literature, the concept of "biological diversity" is used in a broad sense to denote the richness of life in general and its constituent parts, or as a set of parameters of floras, faunas and communities (the number of species and a set of adaptive types, indices reflecting the ratio of species by the number of individuals - evenness , dominance, etc.). Forms of biological diversity can be identified at all levels of life organization. They talk about species, taxonomic, genotypic, population, biocenotic, floristic, faunistic, etc. diversity. Each level has its own systems, categories and methods for assessing diversity. By the beginning of the 21st century, biologists counted up to 2 million species of all groups of organisms: multicellular animals - about 1.4 million species (including insects - about 1 million), higher plants - 290 thousand species (including angiosperms - 255 thousand), mushrooms - 120 thousand species, algae - 40 thousand, protests - 40 thousand, lichens - 20 thousand, bacteria - 5 thousand species. Some authors, taking into account the estimated number of species not yet described, estimate the richness of the modern organic world as a much larger number of species - up to 15 million. In ecology, when analyzing the structure and dynamics of communities, the system of biological diversity of the American ecologist R. Whittaker is widely used. Of the categories of biological diversity he proposed, the most commonly used are alpha diversity (the species structure of a particular community), beta diversity (changes in a number of communities, for example, depending on temperature conditions) and gamma diversity (the structure of biota on the scale of the entire landscape). Syntaxonomy is intensively developing - the classification of plant communities based on their species diversity.

Biological diversity is the main result and at the same time a factor of the evolutionary process. The emergence of new species and life forms complicates the environment and determines the progressive development of organisms. The most complex, evolutionarily advanced forms arise and flourish in the conditions of the equatorial and tropical zones, where the maximum species richness is noted. And life itself could develop as a planetary phenomenon on the basis of the division of functions in primary ecosystems, that is, at a certain level of diversity of organisms. The circulation of substances in the biosphere can only be carried out with sufficient biological diversity, on which the mechanisms of stability and regulation of the dynamics of ecological systems are based. Such important features of their structure as interchangeability, ecological vicariate, multiple provision of functions, are possible only with significant species and adaptive (adaptive forms) diversity.

The level of biological diversity on Earth is primarily determined by the amount of heat. From the equator to the poles, all indicators of biological diversity are sharply reduced. Thus, the share of flora and fauna of the equatorial and tropical zones accounts for at least 85% of the total species richness of the organic world; species living in temperate zones make up about 15%, and in the Arctic - only about 1%. In the conditions of the temperate zone, in which most of Russia is located, the highest level of biological diversity is in its southern strip. For example, the number of bird species from the forest-steppe and broad-leaved forests to the tundra decreases by 3 times, flowering plants - by 5 times. In accordance with the change of natural belts and zones, the structure of the entire biological diversity naturally changes. Against the background of a general decrease in the species richness of the organic world towards the poles, individual groups retain its rather high level and their share in fauna and flora, as well as their biocenotic role, increase. The more severe the living conditions, the higher the proportion of relatively primitive groups of organisms in the biota. For example, the diversity of flowering plants, which form the basis of the Earth's flora, decreases much more sharply with advancement to high latitudes than bryophytes, which in the tundra are not inferior to them in terms of species richness, and are twice as rich in polar deserts. Under conditions of extreme climatic pessimism, for example, in the Antarctic oases, mainly prokaryotes and single species of lichens, mosses, algae, and microscopic animals live.

Increasing the specificity of the environment, extremeness (very high or low temperature, high salinity, high pressure, the presence of toxic compounds, high acidity, and so on) reduce the parameters of biological diversity, in particular, the species diversity of communities. But at the same time, certain species or groups of organisms that are resistant to this factor (for example, some cyanobacteria in heavily polluted water bodies) can multiply in extremely large quantities. In ecology, the so-called basic biocenotic law or Tinemann's rule has been formulated: biotopes with conditions that are sharply different from optimal are inhabited by a smaller number of species, which, however, are represented by a large number of individuals. In other words, the depletion of the species composition is compensated by an increase in the population density of individual species.

Among the areas of study of biological diversity, first of all, there is an inventory of species composition based on taxonomy. Floristics and faunistics, areaology, phyto- and zoogeography are associated with the latter. It is extremely important to know the factors and understand the mechanisms of evolution of biological diversity, the genetic foundations of the diversity of organisms and populations, the ecological and evolutionary role of polymorphism, the laws of adaptive radiation, and the processes of delimitation of ecological niches in ecosystems. The study of biological diversity in these aspects is connected with the most important areas of modern theoretical and applied biology. A special role is given to the nomenclature, typology and inventory of communities, vegetation and animal populations, the creation of databases on various components of ecological systems, which is necessary to assess the state of the entire living cover of the Earth and the biosphere, to solve specific problems of environmental protection, conservation, use of bioresources, many pressing issues of biodiversity conservation at the regional, state and global levels.

Lit.: Chernov Yu.I. Biological diversity: essence and problems // Successes of modern biology. 1991. Vol. 111. Issue. 4; Alimov A.F. et al. Problems of studying the diversity of the animal world in Russia // Journal of General Biology. 1996. V. 57. No. 2; Groombridge V., Jenkins M.D. global biodiversity. Camb., 2000; Alekseev A.S., Dmitriev V.Yu., Ponomarenko A.G. Evolution of taxonomic diversity. M., 2001.