Organisation at Population Level 41
do not produce viable offspring. Rarely, though, some viable or even beneficial mutations occur which increase the species’ fitness and can successfully
lead to the creation of new species.
In each one of the “predator-prey” or “competitor-competitor” systems,
there may be mutual pressure for evolution through the natural selection
mechanism. The predator, for example, compels the prey population towards
differential reproduction, which results in gradual improvement of the mechanisms that the prey possesses in order to avoid predation. Conversely, this
improvement pushes the predator to new improvements of the attack mechanisms against the prey, again through natural selection. These evolutionary
changes that influence each other constitute a co-evolution phenomenon.
3.6 Survival StratEgiES oF PoPulationS
Population is the ecological system that, in the frame of the science of ecology, corresponds to the lowest level of description. The organisms, the
tissues or the cells do not constitute ecological systems because contrary
to population, their elements are not autonomous but specialized, are not
found in random positions, and they cannot distance themselves in space.
Moreover, the organisms, the tissues or the cells have boundaries beyond
which they cannot develop.
The temporal quantitative population alteration is effected under the
influence of the environment that is manifested with the presence of food,
natural conditions, disasters, predation, competition etc. At the same time,
the population undergoes a slow qualitative change through the action of
the environment in the form of natural selection on the population’s individuals. The aim is the maximum increase of its size, with the result that
the population forms a survival and growth strategy.
The study of a population’s adaptation in a stable environment highlights
the connection of some characteristics of the individuals with characteristics of the environment, such as:
• The relation of the individuals’ size with temperature (a big size shows
adaptation to the cold due to an improved relation of surface/size of
the body)
• The relation of the individuals’ colour with the substratum
• Predation behaviour in relation to the prey type
Other characteristics are adaptation to a changing environment that
may, for example, change in time (seasonal periodicity) or exhibit spatial
differentiations, fluctuations, uncertainty etc.
The population has to develop various strategies in order to cope with
the demands of the environment. For example, an effort for adaptation to
do not produce viable offspring. Rarely, though, some viable or even beneficial mutations occur which increase the species’ fitness and can successfully
lead to the creation of new species.
In each one of the “predator-prey” or “competitor-competitor” systems,
there may be mutual pressure for evolution through the natural selection
mechanism. The predator, for example, compels the prey population towards
differential reproduction, which results in gradual improvement of the mechanisms that the prey possesses in order to avoid predation. Conversely, this
improvement pushes the predator to new improvements of the attack mechanisms against the prey, again through natural selection. These evolutionary
changes that influence each other constitute a co-evolution phenomenon.
3.6 Survival StratEgiES oF PoPulationS
Population is the ecological system that, in the frame of the science of ecology, corresponds to the lowest level of description. The organisms, the
tissues or the cells do not constitute ecological systems because contrary
to population, their elements are not autonomous but specialized, are not
found in random positions, and they cannot distance themselves in space.
Moreover, the organisms, the tissues or the cells have boundaries beyond
which they cannot develop.
The temporal quantitative population alteration is effected under the
influence of the environment that is manifested with the presence of food,
natural conditions, disasters, predation, competition etc. At the same time,
the population undergoes a slow qualitative change through the action of
the environment in the form of natural selection on the population’s individuals. The aim is the maximum increase of its size, with the result that
the population forms a survival and growth strategy.
The study of a population’s adaptation in a stable environment highlights
the connection of some characteristics of the individuals with characteristics of the environment, such as:
• The relation of the individuals’ size with temperature (a big size shows
adaptation to the cold due to an improved relation of surface/size of
the body)
• The relation of the individuals’ colour with the substratum
• Predation behaviour in relation to the prey type
Other characteristics are adaptation to a changing environment that
may, for example, change in time (seasonal periodicity) or exhibit spatial
differentiations, fluctuations, uncertainty etc.
The population has to develop various strategies in order to cope with
the demands of the environment. For example, an effort for adaptation to