Fundamentals of Evolution - Korzh O.P. - 2006

Part II. MACROEVOLUTION

Chapter 15. Megaevolution

15.3. The Biosphere as a Global Ecosystem

The term "biosphere" was first coined in 1875 by the Austrian geologist Eduard Suess to designate the regions of Earth's atmosphere, hydrosphere, and lithosphere inhabited by living organisms. A comprehensive and cohesive DOCTRINE OF THE biosphere was subsequently developed by our fellow countryman, V.I. Vernadsky. The biosphere is defined as the envelope of the Earth whose composition, energetics, and Organization are determined by the interaction of its biotic and abiotic components. It encompasses living organisms, their remains, and the Zones of the atmosphere, hydrosphere, and lithosphere inhabited and modified by them. In addition to living matter, the biosphere comprises biogenic matter (products of Organism METABOLISM), bio-inert matter (products of the breakdown and Processing of rocks and sedimentary deposits by living organisms), and inert matter (rocks, Water, etc.). Vernadsky outlined the boundaries of life within the biosphere and comprehensively revealed The Significance of living organisms in planetary-scale processes. He demonstrated that living organisms and their metabolic products constitute the most powerful geological force in nature.

As the living envelope of the Earth, the biosphere is inextricably linked with its non-living envelopes, which are largely the products of the organisms inhabiting them. Therefore, the biosphere must be viewed as an integrated system.

That part of the biosphere currently inhabited by living organisms is called the modern biosphere (neobiosphere), whereas ancient biospheres are referred to as paleobiospheres. However, many specialists insist that the term "biosphere" should strictly apply only to the neobiosphere, giving rise to both the classical (Vernadsky's) and modern Structure/97.html">Definitions. This discrepancy is also reflected in the varying boundaries assigned to the biosphere by different researchers.

According to some estimates, in the atmosphere it extends 8-25 km—up to the ozone layer, since life beyond it is impossible due to the lethal effects of ultraviolet radiation; it completely encompasses the hydrosphere, including the Mariana Trench; and in the lithosphere, it predominantly spans a few meters, though maximum concentrations are observed in the soil layer, with penetration along fissures reaching significantly deeper (hundreds of meters)—these are the BOUNDARIES OF THE neobiosphere. In the view of others, the atmospheric boundaries coincide with present-day limits; in the hydrosphere, they also include all sedimentary rocks altered by living organisms (ranging from hundreds of meters to several kilometers); the same applies to the lithosphere. Consequently, the boundaries of paleobiospheres are expanded considerably compared to the neobiosphere.

Life within the biosphere is distributed unevenly. At its outer limits, only sporadic organisms are found (the so-called field of life's stability). Within the main body of the biosphere, organisms are present continuously (the field of life), yet their distribution remains non-uniform. Vernadsky referred to the zones of maximum concentration of living organisms as films and concentrations of life. These represent the most productive ecosystems and are predominantly located at the interfaces of multiple habitats, where environmental conditions are most favorable.

Living matter refers to the totality of All living organisms, expressed in terms of their mass, energy, and chemical composition. Although living matter constitutes a negligible fraction of the biosphere, it forms its foundation. Due to biological catalysts (Enzymes), Living organisms are capable of driving reactions that do not occur under normal conditions in abiotic nature (even within the technosphere), while significantly accelerating the rates of Chemical Reactions.

The MOST IMPORTANT PROPERTIES of living matter include:

1) the capacity to rapidly occupy all available space—the total amount of living matter remains more or less constant across specific geological periods. This rapid colonization of space is driven both by intensive reproduction and by the ability of organisms to quickly expand their body surface area or that of the communities they form (the total leaf area of all plants per 1 hectare can reach 8-10 hectares);

2) the execution of active locomotion alongside passive movements (The ability to counteract currents, gravity, air currents, etc.);

3) stability during life and rapid decomposition upon death while maintaining high physico-Chemical Activity of organic components;

4) high adaptability to environmental conditions, enabling the colonization of all habitats, including extreme physico-chemical environments (geysers, glaciers, etc.);

5) high reaction rates—exceeding those of non-living matter by hundreds or even thousands of times;

6) a high rate of turnover of living matter—averaging 8 years for The Biosphere as a whole, with the result that the total mass of living matter throughout The history of life exceeds the mass of the Earth approximately 12-fold.

These characteristics lead to an extraordinary concentration of energy within living matter. This phenomenon gives rise to the crucial biogeochemical Functions of living matter:

1) energetic function—the storage of energy during Photosynthesis and its transfer through food chains. According to Vernadsky's biogeochemical principles, geochemical biogenic energy tends toward maximum manifestation; during evolution, those organisms survive whose life activities increase geochemical energy;

2) gas function—the capacity to alter and maintain a specific gaseous COMPOSITION OF THE atmosphere (primarily directed toward reducing atmospheric carbon and its compounds to the current 0.03%, accumulating oxygen, synthesizing ozone, etc.). Two milestone moments in the Evolution of the biosphere are associated with this function: reaching an oxygen level of 1% of the present level (the appearance of the first aerobes and the transition from reducing to oxidizing processes—about 1.2 billion years ago) and reaching an oxygen concentration of 10% of the modern level (colonization of land made possible by The formation of the ozone layer);

3) redox function—associated with the intensification of natural processes (particularly under anthropogenic influence);

4) concentration function—the accumulation within organisms of specific chemical elements dispersed in the environment, resulting in the formation of fossil fuel deposits, etc.;

5) destructive function—The breakdown of organic remains and inorganic matter by organisms, which serves as the foundation for biogeochemical cycles;

6) transport function—the translocation of matter resulting from the active movement of organisms;

7) environment-forming function, which is integrative and involves the transformation of the physico-chemical parameters of the environment. In a broad sense, the outcome of this function is the entire natural environment created and maintained in optimal parameters by living organisms; in a narrow sense, it includes soil formation and the creation of microclimatic conditions (local environment-forming function). It is most pronounced in communities with high biomass, where fluctuations in Temperature, humidity, and other factors are dampened;

8) informational: living organisms and their communities accumulate specific information, encode it within hereditary structures, and pass it on to future generations.

The Role of Living matter is summarized by the law of biogenic migration of atoms. The migration of chemical elements on the Earth's surface and in the biosphere as a whole is carried out with the direct participation of living matter or within environments whose geochemical characteristics are shaped by it. Therefore, by altering the conditions of atomic migration, human activity directly influences the fundamental patterns of geological processes.

This allows us to identify the most crucial CHARACTERISTICS OF THE biosphere as Earth's largest ecosystem. It is a centralized system whose core component is living matter. Certain proponents of anthropocentrism attempt to replace the entire totality of living organisms with just a single species—humans.

The biosphere is an open system: its existence is impossible without an external supply of energy (primarily sunlight). It is also believed that cosmic forces exert a certain influence on the processes taking place within the biosphere.

The biosphere is capable of self-regulation: it can independently maintain Homeostasis by compensating for negative changes and returning to its previous state. This capacity is primarily linked to The properties of living matter, and the foundation of this phenomenon is explained by Le Chatelier's principle—when a system in stable equilibrium is subjected to external forces that disrupt this state, the equilibrium shifts in a direction that counteracts the applied effect.

Like all ecosystems, the biosphere exhibits extraordinary biological diversity. This is driven by differences in habitats, variations among elementary ecosystems and their species assemblages, and the richness of natural zones. Biodiversity is considered the foundation of any ecosystem's stability (Ashby's law of requisite variety). It provides the possibility for functional redundancy, the substitution of specific links, and so on. The biosphere possesses mechanisms that ensure the cycling of matter and the resulting inexhaustibility of individual chemical elements. It is solely due to this that the potential immortality of the biosphere as a biological phenomenon is guaranteed.

According to M.M. Kamshilov, the evolution of life within the biosphere can only occur if the latter consists of relatively independent subsystems capable of changing autonomously. Such subsystems include biocenoses, species, populations, and individuals. The Emergence of new traits in relatively independent populations makes the evolution of the entire macrosystem possible (linking micro- and macroevolutionary levels). If everything were rigidly interconnected, development would be impossible.