The structuring of living organisms into separate classes made it possible to form an idea of the various groups of individuals inhabiting the planet. Of course, there are many contradictions even in modern theories of the evolutionary origin of species, but the basic classifications have a basis that contributes to the ordering of living forms. It is interesting that the concept of a species was introduced into science by Carl Linnaeus back in 1753, but during this time the number of described representatives of different groups of the animal world has increased significantly. And this is not to mention the constant development of approaches to the formation of taxonomy and standardization of plants and animals.
General concepts of species and population
A species is understood as a set of individuals that have a hereditary set of common features determined by morphological, physiological, biological and other features. Actually, this set of features makes it possible to isolate living organisms into separate populations. The classical concept of a species in biology also provides that its representatives in the process of life occupy the same area. At the same time, species is one of the main forms in which living organisms are organized.
But this is not at allmeans that any specialist can easily determine whether an individual belongs to a particular species. For this, a number of criteria are provided for, according to which individuals are entered into different categories of species taxonomy. In turn, a population is a collection of individuals belonging to the same species. This affiliation also determines the common gene pool, the ability to sustainably reproduce offspring and isolation from other species.
View criteria
It has already been noted that the main criteria are represented by special groups of features. Basic among them is the morphological criterion, which is based on external differences between species. This set of features makes it possible to separate organisms that have clear features in terms of external or internal morphological characteristics. But at the same time, one should not exclude the possibility of the presence of difficult-to-determine features that can be detected only in the process of long-term observations.
Geographic criterion also complements the concept of species. The criteria for this type of species are based on the fact that representatives of each group occupy their own special space with common properties. This is the habitat, which will be considered separately.
Another significant criterion is the physiological and biochemical set of features. In terms of reliability, this is the most reliable criterion, since it is based on the differentiation of species according to clear biochemical processes that proceed in the same way in similar categories of living organisms.
Species range
The range is the space defined by the geographical boundaries in which a particular species is distributed. Based on the characteristics of the biosphere in the area, it is possible to draw conclusions about the sizes and shapes that distinguish the inhabitant of this space. Actually, the area can be used as a full-fledged criterion for determining whether an individual belongs to a particular species, but here it is important to take into account some nuances.
Firstly, it is obvious that representatives of different species can live in one area. Secondly, the concept of species admits that the geographical criterion may be completely absent when it comes to the so-called cosmopolitans. These are species that theoretically can spread throughout the planet, regardless of terrain conditions, climatic features, etc. Scientists also identify rapidly dispersing groups of individuals of different species that can change their range in such a way that specialists do not have time to determine its characteristic features. These individuals include house flies and sparrows.
The concept of species and population in ecology
In ecology, a species and a population are considered in the general context of the interaction of individuals with representatives of other groups. The main parameters for the study of species by ecologists are the population size, type of food, habitat, timing of reproduction, etc. These and other indicators allow specialists to attribute populations to certain ecological niches. Directly ethological criterion is reduced toidentification of behavioral differences in representatives of different species. Also, the concept of a species in ecology is determined by a complex of biological and abiotic conditions in which the population was formed and adapted to life.
Speciation process
The formation of new species occurs in different ways, which are divided into two main groups. As a rule, speciation occurs as a result of the so-called phyletic evolution. In accordance with this concept, developmental processes within one population eventually lead to the fact that the adaptability of organisms to a particular environment increases, resulting in significant changes in the characteristics of the group.
The second form of speciation is based on splitting the group into two categories. As noted above, the concept of species involves the use of several features to systematize individuals in order to assign them to specific populations. The greatest difficulty in such classifications is caused precisely by the manifestation of speciation through splitting.
Modern concepts of speciation
There are two approaches to the definition of speciation as a result of group splitting. These are allopatric and sympatric speciation. In the first case, the process of expanding the habitat of the original species under conditions of long-term residence of the population against the background of geographic isolation is implied. An important condition for the formation of species features sufficient to distinguish isolated individuals into a separate group isnamely, isolation from the original representatives of the primary population. Natural geographic divisions can occur when fenced in by mountain ranges, sea straits, etc.
To determine the sympatric form of the formation of new groups, it should be noted that the concept of species provides for the considerable importance of the food specialization of individuals. It is the division on this basis that determines the principles for the formation of new species within the original group.
Conclusion
All the same, the taxonomy of species of living organisms that exists today is far from perfect. The fact is that even high-tech tools and methods for identifying the characteristics of various individuals do not always allow them to be identified with sufficient accuracy as representatives of a particular species category.
The very concept of a species is also changing, supplemented by new aspects of biological, geographical and ecological properties. Of course, a special place is still occupied by the physiological characteristics of living organisms, which form the basic set of features for the formation of taxonomy. Difficulties in classification usually arise when new forms are found that are intermediate between different species.
