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Ecology: the biology of interaction. 5.20. Concept of effective temperatures
The development of many poikilothermic organisms is fairly well described using the concept of effective temperatures, which treats heat as a resource necessary for development.
Ecology: The Biology of Interaction. 5.19. Thermobiological Types of Organisms
In cases where various processes affect some parameter critical to biosystems, it is customary to regard the regulation of that parameter as a balance. As noted previously, temperature is the most important condition, exerting a high degree of influence on the course of all biological processes. According to the type …
Ecology: Biology of Interaction. 5.18. Photoperiodism
Photoperiodism is regulation of the seasonal cycle depending on day length, a regulatory mechanism widespread in temperate zones. Unlike circadian rhythms, which are controlled by alternation of light and darkness, annual (circannual) rhythms are controlled by day length.
Ecology: Biology of Interaction. 5.17. Adaptive Biorhythms
Influence of sunlight on many biological phenomena is mediated by daily changes in illumination intensity, changes in day length, and associated seasonal alternation. Dynamics of lunar gravitation and lunar phases also set periodic changes. These and other factors give rise to adaptive biological rhythms: daily, tidal, seasonal, multiyear, and others.
Ecology: biology of interactions. 5.16. Water balance of organisms
Regardless of the external environment in which an organism finds itself, the concentration of aqueous solutions in its internal milieu is vital for its survival. To preserve life, this concentration must be maintained within relatively narrow limits. The organism's membranes are permeable to both water and certain dissolved substances. The …
Ecology: Biology of Interaction. 5.15. Greenhouse Effect
Earth’s atmosphere transmits radiation from the Sun and Earth differently: it is almost transparent to visible light but effectively retains far-infrared radiation. As a result, energy reaches Earth’s surface more easily than it leaves it, which warms the planet. This phenomenon is called the greenhouse effect.
Ecology: Biology of Interaction. 5.14. Atmospheric Absorption of Solar Radiation
The atmosphere is selectively permeable to different parts of the electromagnetic spectrum. Ionizing radiation and most ultraviolet radiation are effectively absorbed by the ozone layer (atmospheric zone with high ozone content), while the spectral region from infrared to short-wave radio radiation is absorbed by water vapor, carbon dioxide, methane, and …
Ecology: biology of interaction. 5.13. Biological effects of electromagnetic radiation
Terrestrial organisms live in an environment saturated with EM radiation of various wavelengths and intensities. It should be noted that humanity has added many artificial sources to the natural ones, especially in the radio range. The diversity of effects of this radiation on organisms has not yet been fully studied.
Ecology: Biology of Interaction. 5.12. Composition of Solar Radiation
Temperature of the Sun’s outer surface is about 6000 K, and maximum solar emission falls in the visible spectrum region near wavelength 550 nm. Earth is much cooler and emits predominantly in the far-infrared range.
Ecology: biology of interaction. 5.11. Features of organisms related to their size
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Ecology: Biology of Interaction. 5.10. Selye’s Concept of Stress
As established in 1936 by Canadian scientist Hans Selye, very different effects on humans and other animals can trigger a similar response associated with nervous and endocrine system activity.
Ecology: Biology of Interaction. 5.09. “Interaction of Factors” and the Hutchinson Niche
The result of factor interaction depends on factor specifics and on mechanisms of adaptation to their adverse effects, but one general rule can still be stated: unfavorable values of one factor narrow tolerance ranges to other factors.
Ecology: Biology of Interaction. 5.08. Terms Describing Organism Tolerance
Different organisms differ both in the width and in the position of their characteristic tolerance ranges. Range width is indicated by the prefix “eury-” (broad) versus “steno-” (narrow); adaptation to high values by “poly-”, and to low values by “oligo-”.
Ecology: Biology of Interaction. 5.07. Shelford’s Principle of Tolerance
Shelford’s principle can be stated as follows: among values of any condition there is a tolerance range within which the studied organism can exist. The limiting condition is the one whose value deviates most strongly from the optimum.
Ecology: Biology of Interaction. 5.06. Liebig’s Law of the Minimum
A factor whose small changes produce the strongest effects on the considered organisms and therefore determine limits of their development or distribution is called limiting. In resource terms, the limiting factor is the resource in shortest relative supply.
Ecology: Biology of Interaction. 5.05. Key Factors in Earth’s Biosphere
Considering Earth’s biosphere, we can identify which factors most strongly affect distribution of organisms across the planet’s surface. Factors whose variation most often coincides with species distribution boundaries are limiting factors. For terrestrial ecosystems these are primarily temperature and moisture; for aquatic ecosystems, light and biogens.
Ecology: Biology of Interaction. 5.04. Subenvironments and Adaptations to Them
By their importance for organisms, ecological factors can be divided into requisites (obligatory factors without which organisms cannot exist) and accessories (factors whose influence is not vital). Environmental context can also be analyzed as a set of relatively independent subenvironments requiring different adaptive complexes.
Ecology: Biology of Interaction. 5.03. Proper Ecological Classifications of Ecological Factors
One of the most important classifications is the division of ecological factors into conditions and resources. Resources are consumed by organisms and are therefore depleted and exhaustible, whereas conditions influence organisms, can be modified by them, but are not consumed and cannot be exhausted.
Ecology: Biology of Interaction. 5.02. Classification of Environmental Factors by Origin
To describe and study environment, its properties are conventionally considered separately and called factors. An environmental factor is a specific characteristic, process, or property of surrounding environment that can potentially influence organisms; an ecological factor is one that actually influences the studied organism or population.
Ecology: Biology of Interaction. 5.01. Environment and Ecological Environment
Chapter 5. Autecology and foundations of environmental science. Defining ecology as a science, we state that it studies interactions of organisms and supra-organismal systems with the environment. From this definition it is clear that the key property of ecological environment is not merely to surround, but to influence.