ECOLOGICAL BIOCHEMISTRY - Study Guide - V. M. Isaenko 2005

Chapter 8. PLANT AND ANIMAL RESISTANCE AND ADAPTATION

Living organisms exhibit remarkable diversity not only in their shape, size, and internal Structure, but also in their ecological, morphological, physiological, genetic, and biochemical adaptations to the environment. These adaptations Complement one another and contribute to the enhanced survival and reproduction of organisms.

An examination of ECOLOGICAL AND BIOCHEMICAL interactions among organisms is impossible without addressing their resistance and ADAPTATION TO ENVIRONMENTAL conditions.

Organisms are subject to A wide variety of biotic and abiotic factors. The most significant among these are: 1) climatic factors (Temperature, humidity, seasonality, day length, light intensity, etc.); 2) edaphic factors encompassing soil-related resources and conditions (mineral content, soil microflora, etc.); 3) atmospheric factors (gaseous content, Water vapor, etc.); 4) hydrological factors in aquatic ecosystems (PHYSICOCHEMICAL PROPERTIES OF water, water movement, etc.); 5) anthropogenic toxic substances (industrial emissions, pesticides, etc.); 6) elevated radiation levels (electromagnetic, ionizing radiation, etc.); 7) disease-causing infections; 8) substances secreted by microorganisms, Fungi, plants, animals, and their metabolites.

The Effect of biotic and abiotic factors on organisms can be either favorable or unfavorable. Moreover, their impact occurs in specific proportions. Various Forms of interaction among these factors are recognized. One is synergistic action, where their combined impact amplifies the overall effect. Another is antagonistic action, which results in the suppression (inhibition) of one factor's influence by another. Yet another form of interaction is indifferent action, characterized by the independent influence of different factors.

All living organisms existing within ecosystems can be divided into two groups: autochthons (from the Greek autos — self, and chthon — earth) and allochthons (from the Greek allos — other). The former have evolved in a specific locality or have inhabited it since ancient times and continue to do so today. They are permanently present in the given ecosystem due to the constant availability of nutrients and other conditions for existence. The latter inhabit the given locality but originated through the historical development of organisms elsewhere. The presence of these organisms depends on sporadic increases in their nutrient supply, The Emergence of favorable living conditions, and similar factors.

Under normal ecosystem conditions, numerous species of organisms develop. Under extreme conditions, however, those organisms that have successfully adapted to their habitat and to The impact of the extreme factor become predominant.