From the point of view of ecological research, the features are a little more
shaded. Because a species is represented by different populations, which belong to a
certain type of biocenosis (which, in their turn are integrated in similar or different
ecosystems). As a result, the areal of a species is determined by the number and the
dispersal of these ecosystems. Because of the variety of the elements of the abiotic
environment within the areal of respective species, even in the case of a defined
ecosystem type (for instance, deciduous forests, marine stony costal areas, or
swamp ecosystems) the structure of the biocenosis is not the same, because the
ecological niches of the populations belonging to different species will not be the
same. Moreover, between these populations occur – more or less frequently –
exchanges of individuals which – joining a new population, bring their own genetic
inheritance and the peculiarities of the ecological niche from which they came. As a
consequence, their entering into another population represents for this an enrichment from the genetic and ecologic points of view. These newly arrived individuals
determine an increase of diversity and stability of the entered population, reducing,
also, endogamy processes, otherwise inherent.
If a species is eurioic, hence it has a high capacity to adapt to broad variations of
biotic and abiotic factors, it is really an eurioic species; it is able to be a part of the
biocoenoses from a large range of ecosystems. Therefore it has an increased
capacity to survive. That seems to be a good thing. But . . . in the case it enters a
weakened ecosystem, characterized by a reduced ecological stability, i.e. a more
brittle ecosystem, the respective species occupies the ecological niche of another,
more feeble species, which is thus eliminated; the newly entered species thus
becomes an invading species. This situation is more obvious in the case when
several ecosystems suffer perturbations (usually due to human bad interventions –
pollution, chemical treatments, hydrotechnical developments – as man-made reservoirs, overexploitation etc). So, invasive species may seriously disturb their
ecological balance.
Within the population of a species, the individuals have to adapt continuously to
the oscillations of environmental specific features. This way, the resulting adaptations may be gradually included into the genetic inheritance of the respective
population.
Some species may have a single population; these are unipopulational species,
and they are deeply endangered by extinction. Other species have numerous
populations, which live either in a single type of ecosystems, or in many ecosystems. They are multipopulational species.
Population is a proof how the living nature, through very simple elements, but
through complex actions, generates complicated functions which ensure the existence, development and perpetuation of life on our planet.
Within the areal of a species two identical populations do not exist. The more
distant the populations, the more different their ecological niches. This situation
stimulates segregation of the species in subspecies which, gradually, by successive
adaptations will lead to apparition of new species. Even before speciation, individuals, from very distant populations will interbreed with difficulty with individuals
of local population, or death rate of the descendants will be much higher.
30 Population – Structural and Functional Basic Element of Bioceonosis and. . .
511
shaded. Because a species is represented by different populations, which belong to a
certain type of biocenosis (which, in their turn are integrated in similar or different
ecosystems). As a result, the areal of a species is determined by the number and the
dispersal of these ecosystems. Because of the variety of the elements of the abiotic
environment within the areal of respective species, even in the case of a defined
ecosystem type (for instance, deciduous forests, marine stony costal areas, or
swamp ecosystems) the structure of the biocenosis is not the same, because the
ecological niches of the populations belonging to different species will not be the
same. Moreover, between these populations occur – more or less frequently –
exchanges of individuals which – joining a new population, bring their own genetic
inheritance and the peculiarities of the ecological niche from which they came. As a
consequence, their entering into another population represents for this an enrichment from the genetic and ecologic points of view. These newly arrived individuals
determine an increase of diversity and stability of the entered population, reducing,
also, endogamy processes, otherwise inherent.
If a species is eurioic, hence it has a high capacity to adapt to broad variations of
biotic and abiotic factors, it is really an eurioic species; it is able to be a part of the
biocoenoses from a large range of ecosystems. Therefore it has an increased
capacity to survive. That seems to be a good thing. But . . . in the case it enters a
weakened ecosystem, characterized by a reduced ecological stability, i.e. a more
brittle ecosystem, the respective species occupies the ecological niche of another,
more feeble species, which is thus eliminated; the newly entered species thus
becomes an invading species. This situation is more obvious in the case when
several ecosystems suffer perturbations (usually due to human bad interventions –
pollution, chemical treatments, hydrotechnical developments – as man-made reservoirs, overexploitation etc). So, invasive species may seriously disturb their
ecological balance.
Within the population of a species, the individuals have to adapt continuously to
the oscillations of environmental specific features. This way, the resulting adaptations may be gradually included into the genetic inheritance of the respective
population.
Some species may have a single population; these are unipopulational species,
and they are deeply endangered by extinction. Other species have numerous
populations, which live either in a single type of ecosystems, or in many ecosystems. They are multipopulational species.
Population is a proof how the living nature, through very simple elements, but
through complex actions, generates complicated functions which ensure the existence, development and perpetuation of life on our planet.
Within the areal of a species two identical populations do not exist. The more
distant the populations, the more different their ecological niches. This situation
stimulates segregation of the species in subspecies which, gradually, by successive
adaptations will lead to apparition of new species. Even before speciation, individuals, from very distant populations will interbreed with difficulty with individuals
of local population, or death rate of the descendants will be much higher.
30 Population – Structural and Functional Basic Element of Bioceonosis and. . .
511