to be reconsidered. And this can be done only if the populational structure of
species is taken into consideration.
Apparently, autecology deals with the study of the relations of a species to its life
environment. One of us (N.Donit ¸a ˘) states that autecology is the totality of the
adaptations to the biotic and abiotic way of life, during the course of evolution,
adaptations which are assigned by heredity.
Ecological populations of a species, through the relations within the ecosystems
where they occur, acquire certain quantitative characteristics, not hereditary, which
depend on the environment of each type of ecosystem. These characteristics, which
may be expressed as several ecological values, are classified as:
– A. Structural parameters: types of biocoenosis to which they belong, size of
population (number or effective), density, specific adaptations to environmental
features, frequency, level of aggregation, rate of apparition/disappearance, rate
of increasing/decreasing of population size, genetic structure;
– B. Functional parameters: age structure, sex ratio, birth/death rate, growth
rhythm, ingesta/excreta, basic metabolism, bioaccumulation, dynamics of biomass augmentation, specific chemical compounds, energy budget, gross production, net production, necromass production, spreading in territory, specific
adaptations to oscillations of environmental features;
– C. Behavioral parameters: way of life, biorhythm, intraspecific relations (feeding, reproduction, social relations, self-defending relations) and interspecific
relations (trophic, cohabitation, competition, symbiosis, tolerance, selfdefending, sheltering etc).
These population parameters point to the quantitative side of species autecology.
Adaptation to the peculiarities of an ecosystem – the first organization level in
ecology – was achieved gradually and evolved continuously, it corresponding to
evolution stage of respective ecosystem (juvenile, maturity or senescence). From
our point of view, the population of a species is in a continuous adaptation to the
oscillations of all environmental factors. And these adaptations must be, always,
adequate to reality. In a contrary situation the population suffers, mortality
increases, and the population becomes vulnerable in competition with the other
species of that biocoenosis. This process of adequate adaptation determines – at the
population level – permanent, quite imperceptible changes, even change of genetic
characters which, this way, may become hereditary.
All the species show adaptations to each environmental factor (considered
separately), but also to certain sets of factors (climate, water chemistry – for aquatic
organisms, soil chemistry, periodical or accidental variations of weather features,
pollution etc) (Odum 1971; Brewer et al. 1994; Chapman and Reiss 1992).
Adaptations may have different amplitudes. In certain cases, such modifications
of the entire population are quite subtle; in other cases, there are deaths of part of
individuals, and behavioral or physiological changes occur. If a species is euryoic,
it will tolerate easier the changes; if it is stenoic, sacrifices will be more important.
Moreover, the populations of euryoic species can live in a lot of types of ecosystems, while the stenoic ones – only in one type of ecosystems. More adequate are
30 Population – Structural and Functional Basic Element of Bioceonosis and. . .
513
species is taken into consideration.
Apparently, autecology deals with the study of the relations of a species to its life
environment. One of us (N.Donit ¸a ˘) states that autecology is the totality of the
adaptations to the biotic and abiotic way of life, during the course of evolution,
adaptations which are assigned by heredity.
Ecological populations of a species, through the relations within the ecosystems
where they occur, acquire certain quantitative characteristics, not hereditary, which
depend on the environment of each type of ecosystem. These characteristics, which
may be expressed as several ecological values, are classified as:
– A. Structural parameters: types of biocoenosis to which they belong, size of
population (number or effective), density, specific adaptations to environmental
features, frequency, level of aggregation, rate of apparition/disappearance, rate
of increasing/decreasing of population size, genetic structure;
– B. Functional parameters: age structure, sex ratio, birth/death rate, growth
rhythm, ingesta/excreta, basic metabolism, bioaccumulation, dynamics of biomass augmentation, specific chemical compounds, energy budget, gross production, net production, necromass production, spreading in territory, specific
adaptations to oscillations of environmental features;
– C. Behavioral parameters: way of life, biorhythm, intraspecific relations (feeding, reproduction, social relations, self-defending relations) and interspecific
relations (trophic, cohabitation, competition, symbiosis, tolerance, selfdefending, sheltering etc).
These population parameters point to the quantitative side of species autecology.
Adaptation to the peculiarities of an ecosystem – the first organization level in
ecology – was achieved gradually and evolved continuously, it corresponding to
evolution stage of respective ecosystem (juvenile, maturity or senescence). From
our point of view, the population of a species is in a continuous adaptation to the
oscillations of all environmental factors. And these adaptations must be, always,
adequate to reality. In a contrary situation the population suffers, mortality
increases, and the population becomes vulnerable in competition with the other
species of that biocoenosis. This process of adequate adaptation determines – at the
population level – permanent, quite imperceptible changes, even change of genetic
characters which, this way, may become hereditary.
All the species show adaptations to each environmental factor (considered
separately), but also to certain sets of factors (climate, water chemistry – for aquatic
organisms, soil chemistry, periodical or accidental variations of weather features,
pollution etc) (Odum 1971; Brewer et al. 1994; Chapman and Reiss 1992).
Adaptations may have different amplitudes. In certain cases, such modifications
of the entire population are quite subtle; in other cases, there are deaths of part of
individuals, and behavioral or physiological changes occur. If a species is euryoic,
it will tolerate easier the changes; if it is stenoic, sacrifices will be more important.
Moreover, the populations of euryoic species can live in a lot of types of ecosystems, while the stenoic ones – only in one type of ecosystems. More adequate are
30 Population – Structural and Functional Basic Element of Bioceonosis and. . .
513