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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 effects depends on sociocultural context.
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 all against all. Of course, this is not the case. …
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 predators, and by increasing parasitic infections.
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 contribution to future generations. The measure used for this purpose …
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 direct influence on each other.
About What Did Not Fit into the Frame
During the recording of the TV program about frog research, much simply did not fit into the frame. Once the program is released, I want to post additional materials here to provide a broader context for discussing the life and evolution of these remarkable animals.
Coffee and the Third Nature. Column in KompyuterraOnline #19
In the case of living systems, we perceive structure above all else. That structure must be continuously maintained, "fed." Drinking coffee with sugar — the episode that prompted our discussion — is part of this process.
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 is also intraspecific competition, which unfolds...
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 is associated with one host. To exploit a host, parasites …
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 a single prey species) and oligophages (oriented toward several closely …
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 that they consume other living organisms, and consumption requires depriving …
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 between protocooperation and mutualism...
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 relationships...
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 no influence (0). However...
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 a larger number of resources. The parameter K for each …
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, resources are depleted, and growth slo...
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 time interval and recording their age at...
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 such that they can only be measured over a spe...