Biological species are made up of populations. What does this term mean? A population is a certain group of individuals of the same biological species inhabiting a certain space, partially isolated from other similar communities. A relatively stable population can reproduce itself for several generations.
The size of the territory occupied by different populations is not the same. They depend on the size of the organism and its lifestyle. Bacteria, a fraction of a micron long, choose very small areas for their populations. For large mammals, the habitat is measured in square kilometers.
Why do species exist in populations?
Relationships between members of the same group are diverse. Often they depend on each other. Why do species exist as populations? The answer is simple: because it's easier to survive.
In some cases, members of a population may competeand even fight for certain environmental factors (light, mineral nutrition in plants, territory in animals). But most of the time they help each other. This is especially pronounced in colonial nesting birds and ungulates leading a herd lifestyle.
Gene exchange and transfer of hereditary properties
When answering the question why biological species exist in the form of populations, perhaps the most important factor should be recognized as a facilitated reproduction process. It ensures the exchange of genes, the transfer of hereditary properties from parents to offspring. These relationships are somewhat weakened in populations where parthenogenetic reproduction predominates. This is characteristic of some insects, for example, aphids. Many plants are vegetatively propagated. Such are the gout that live in deciduous forests and the lady's slipper, the couch grass that creeps in the meadows. Some species of animals reproduce vegetatively - corals, sponges.
Structure
A population exists in space in the form of a certain biological scheme. Its character, worked out by the mechanism of natural selection, makes it possible to economically use the ecological resources of the territory and maintain biologically necessary contacts between the individuals that make up the population. This allows us to understand why species exist in the form of populations and subspecies.
The spatial distribution of the group depends on the size of the feeding areas in animals or on the required feeding area in plants. This process may be accompanied by an aggravation of competitive relations. Often it leads to the death of the weakest individuals in plants, the expulsion of those in animals. Many animals mark occupied areas with urine, odorous secretions of special glands, and sound signals. The latter is especially common in birds. Many animals demonstrate their right to territory or actively defend it by their behavior.
There are many reasons why species exist in populations, but the main ones are: mutual aid, easier reproduction, more efficient use of resources.
