Structuring of living organisms into separate classes allowed us to form an idea of the various groups of individuals that inhabit 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 helps to organize the living forms. It is interesting that the concept of the species was introduced into science by Karl Linnaeus back in 1753, but during this time the number of representatives of different groups of the animal world described has increased significantly. And this is not to mention the constant development of approaches to the formation of systematics and standardization of plants and animals.
General concepts of species and population
A species is understood as a collection of individuals in which a hereditary set of common features is observed, determined by morphological, physiological, biological, and other characters. Actually, this set of features makes it possible to isolate living organisms into separate populations. The classical concept of species in biology also provides that its representatives in the process of life occupy the same area. At the same time, the species is one of the main forms in which living organisms are organized.
But this does not mean at all that any specialist can easily determine whether an individual belongs to a particular species. For this, a number of criteria are provided by which individuals are recorded in different categories of species systematics. In turn, a population is a collection of individuals belonging to the same species. This affiliation also determines the general gene pool, the ability to sustainable reproduction of offspring and isolation from other species.
View criteria
It has already been noted that the main criteria are represented by special groups of features. The basic among them is the morphological criterion, which is based on external differences between species. This set of features allows the separation of organisms that have obvious features in terms of external or internal morphological characteristics. But at the same time, one should not exclude the likelihood of the presence of complexly defined features that are detectable only during long-term observations.
The geographical criterion also complements the concept of species. Criteria of the type of this type are based on the fact that representatives of each group occupy their own special space with common properties. This is the habitat that will be considered separately.
Another significant criterion is a physiological and biochemical set of characters. In terms of reliability, this is the surest criterion, since it is based on the distinction between species according to clear biochemical processes that occur equally in similar categories of living organisms.
Area of view
An area is a space defined by the geographical boundaries in which a particular species extends. Based on the characteristics of the biosphere in the range, we can 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 assumes that a geographical criterion may be absent altogether when it comes to so-called cosmopolitans. These are species that theoretically can spread throughout the planet, regardless of the terrain, climatic features, etc. Scientists also identify fast-dispersing groups of individuals of different species that can change their habitat in such a way that specialists do not have time to determine its characteristic features. Such individuals include house flies and sparrows.
The concept of species and population in ecology
In ecology, the species and population are considered in the general context of the interaction of individuals with representatives of other groups. The main parameters for studying the species by ecologists are the population size, type of food, habitat, breeding dates, etc. These and other indicators allow specialists to classify populations in certain ecological niches. The ethological criterion itself comes down to identifying behavioral differences in representatives of different species. Also, the concept of a species in ecology is determined by a set of biological and abiotic conditions in which a population was formed and adapted to life.
Speciation process
The formation of new species occurs in different ways, which are distinguished into two main groups. As a rule, speciation occurs as a result of the so-called phyletic evolution. In accordance with this concept, the development processes within one population ultimately lead to the fact that the adaptability of organisms to a specific environment increases, as a result of which there are 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 a species involves the use of several characters to systematize individuals in order to classify them in specific populations. The greatest difficulties in such classifications are caused by the manifestation of speciation through splitting.
Modern speciation concepts
There are two approaches to determining speciation as a result of splitting groups. This is allopathic and sympatric speciation. In the first case, the process of expanding the habitat of the original species in conditions of a long stay of the population against the background of geographical isolation is implied. An important condition for the formation of species features sufficient to isolate isolated individuals into a separate group is precisely the isolation from the initial representatives of the primary population. Natural geographical separation can occur when barriers are made 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 considerable importance for the food specialization of individuals. It is the division on this basis that determines the principles of the formation of new species within the original group.
Conclusion
Nevertheless, the current systematics of species of living organisms 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 us to accurately determine them as representatives of a particular species category.
The very concept of the species is changing, supplemented by new aspects of biological, geographical and environmental properties. Of course, the physiological characteristics of living organisms, which form the basic set of attributes for the formation of systematics, still occupy a special place. Difficulties in classification usually arise when new forms are found that are intermediate between different species.