#Екологія (стара, російською)
124 materials
Ecology: Biology of Interaction. 4.18. (supplement) How Parasites “Set Up” Their Hosts
A correlation has been detected between the degree of Toxoplasma infection in different peoples and cultural traits of those peoples. Available data suggest the parasite may intensify feelings of anxiety, uncertainty, depression, and guilt in humans, though expression of these …
Ecology: biology of interaction. 4.17. (supplement) Intraspecific interaction strategies
It can be said that a significant portion of organisms lives in two fundamentally different environments: the external and the intra‑population ones. It might give the impression that a population — is an arena of struggle and uncompromising competition of …
Ecology: Biology of Interaction. 4.16. Regulation of Population Size
The abundance of every population is controlled by multiple negative feedback loops. When population size begins to grow, it is constrained by shortage of its own resources, by switching of polyphagous predators to feeding on it, by overreproduction of specialized …
Ecology: The Biology of Interaction. 4.15. Ecological Strategies
Therefore, the individual of greatest value to the population must be one that allocates resources between its own survival and reproduction in an optimal combination. This optimality can be assessed by calculating which allocation, under given conditions, maximises an individual's …
Ecology: Biology of Interactions. 4.14. Amensalism and Neutralism
Amensalism, a relationship in which one population is adversely affected by another while the latter is unaffected by the former, is an extreme case of competitive interaction. Neutralism, by contrast, is a case where populations in one ecosystem have no …
Ecology: biology of interaction. 4.13. Competition and ecological niches
As we have established, competition is defined as a relationship between two populations in which the increase of each causes a decrease in the size of the other. However, this definition applies only to interspecific competition, and besides it there …
Ecology: The Biology of Interactions. 4.12. Parasitism
True parasites are very tightly associated with their hosts. They live inside hosts or are firmly attached to host surfaces. The host is the habitat for parasites or its key component. Usually, during life (or one life-cycle stage), a parasite …
Ecology: biology of interaction. 4.11. Predation
Thus, based on the degree of specialization of predators in feeding on particular categories of prey, they can be divided into generalists and specialists. Closely related to this classification is the division of predators into monophages (adapted to feeding on …
Ecology: The Biology of Interactions. 4.10. Diversity of Exploitation Forms
From an ecological point of view, predators include both a ladybird hunting aphids, a daphnia filtering algae from water, and even a sundew gradually digesting a mosquito that landed on its leaf. What all these organisms have in common is …
Ecology: The Biology of Interactions. 4.09. Commensalism
Commensalism is the direct or environment-mediated relationship between two populations in which one—the commensal population—benefits (increases in abundance in response to increasing abundance of its partner), while the other—the host population—is indifferent and does not depend on commensal abundance...
Ecology: The Biology of Interactions. 4.08. Protocooperation
As follows from the definition above (see section 4.6), protocooperation is a non-obligatory mutually beneficial relationship between two populations. Species linked by this relationship may occur both together and separately. Often, it is very difficult to draw a clear boundary …
Ecology: The Biology of Interactions. 4.07. Mutualism
From the definition of mutualism as mutually beneficial relationships between populations that occur together in nature, one might think this is some exotic phenomenon. This is far from the case: for example, developed terrestrial life exists only thanks to mutualistic …
Ecology: biology of interaction. 4.06. Classification of relationships between populations
Classify the relationships between species based on the influence they exert on each other was proposed, for example, by the renowned American ecologist Eugene Odum. He distinguished three types of relationships between populations: positive influence (+), negative influence (–) and …
Ecology: The Biology of Interactions. 4.05. The Lotka-Volterra Model
The Lotka-Volterra model played an exceptional role in the development of mathematical ecology. As is easy to see, many other, more complex models can be built on its basis. For example, they can describe relationships not between two but among …
Ecology: The Biology of Interactions. 4.04. Exponential and Logistic Growth of Population Size
Population increase is proportional to population size; therefore, if growth is not limited by external factors, the population grows with acceleration. Its dynamics are described by the exponential population growth model. Naturally, exponential growth cannot continue forever. Sooner or later, …
Ecology: biology of interaction. 4.03. Demographic tables, pyramids and survival curves
Demographic tables are convenient for monitoring the dynamics of birth and death rates across different age and/or sex groups. One of the methods of constructing them involves tracking the fate of a specific cohort of individuals born within a short …
Ecology: The Biology of Interactions. 4.02. Population Characteristics
Demographic characteristics of populations can be divided into two groups: static and dynamic. Static characteristics can be determined for a specific moment in time; an example is population size. Birth rate, mortality, and migration are dynamic characteristics. Their nature is …
Ecology: the biology of interaction. 4.01. Populations and their properties
Chapter 4. Population Ecology The concept «population» — one of the most important in biology. As often happens with key terms, it is used in various senses. To the definition of the concept «population» formal, concrete and theoretical approaches are …
Ecology: biology of interaction. 3.16. (supplement) Biomes and human culture
The features of the natural environment determine the characteristic relationships between it and human society, and therefore also the characteristic features of the society. Humans have evolved as a species with extremely plastic behavior, capable of occupying diverse ecological niches …
Ecology: The Biology of Interactions. 3.15. (supplement) Ecosystem Efficiency and Energy Subsidies
Ecosystems can be assisted by external energy inputs. To prevent weeds from choking wheat in a wheat field, humans invest additional energy. In primitive agriculture this energy can be muscular (for example, hand weeding), while in modern agriculture energy needs …