The concept of species and population, modern views on speciation, criteria of the species

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 basic classifications have a basis that facilitates the ordering of living forms. It is interesting that the concept of the species was introduced into the science of Carl Linnaeus as far back as 1753, but during this time the number of representatives of different groups of fauna described has increased many-fold. 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

Under the guise is understood the totality of individuals who have a hereditary set of common traits determined by morphological, physiological, biological and other characteristics. Actually, this set of features also 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 vital activity 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 that any specialist can easily determine the belonging of a particular individual to a particular species. To this end, a number of criteria are envisaged, according to which individuals are entered in different categories of species taxonomy. In turn, the population is a collection of individuals belonging to the same species. This accessory also determines the general gene pool, the ability to sustain reproductive progeny and isolation from other species.

Type Criteria

It has already been noted that the main criteria are represented by special groups of characteristics. The basic among them is the morphological criterion, which is based on external differences between species. This set of characteristics makes it possible to separate organisms that have distinct features in terms of external or internal morphological characteristics. However, it should not be ruled out that there is a probability of having difficultly determined features that can be detected only in the course of long-term observations.

The geographic criterion also complements the concept of the species. Criteria for this type of species are based on the fact that the representatives of each group occupy their own special space with common properties. This is the habitat, which will be considered separately.

Another important criterion is the physiological-biochemical set of characteristics. In terms of reliability, this is the most correct criterion, because it is based on the differentiation of species according to clear biochemical processes that occur in similar categories of living organisms.

Area of the species

The area is a space defined by geographical boundaries, in which a particular species extends. Based on the characteristics of the biosphere in the range, it is possible to draw conclusions about the sizes and forms that distinguish the inhabitant of a given space. Actually, the range can be used as a full-fledged criterion for determining the individual's belonging to a particular species, but here it is important to take into account certain nuances.

First, it is obvious that representatives of different species can live in one area. Secondly, the concept of a species admits that a geographical criterion may not exist at all, if we are talking about so-called cosmopolitans. These are species that can theoretically spread all over the planet, regardless of terrain conditions, climatic features, etc. Scientists also identify rapidly dispersing groups of individuals of different species that can change the range 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 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 classify populations in certain ecological niches. The directly ethological criterion is reduced to the identification 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.

The process of speciation

Formation of new species occurs in different ways, which are distinguished in two main groups. As a rule, speciation occurs as a result of the so-called phyletic evolution. In accordance with this concept, the processes of development within a single population eventually lead to the fact that the fitness 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 the species provides for the use of several characters for the systematization of individuals with a view to their assignment to specific populations. The greatest difficulty in such classifications is caused by the manifestation of speciation by splitting.

Modern concepts of speciation

There are two approaches to the determination of speciation as a result of the splitting of groups. This is allopatric and sympatric speciation. In the first case, the process of expanding the habitat of the original species in the conditions of a long stay of the population against the background of geographical isolation is implied. An important condition for the formation of features of a species sufficient to isolate isolated individuals into a separate group is precisely the fence from the original representatives of the primary population. Natural geographical separation can occur when fencing with mountain ranges, sea straits, etc.

To determine the sympatric form of the formation of new groups, it should be noted that the concept of the species provides considerable significance to the food specialization of individuals. It is the division in this feature that determines the principles of the formation of new species within the original group.

Conclusion

Nevertheless, the systematics of the species of living organisms that exist today are far from perfect. The fact is that even high-tech tools and methods for revealing the characteristics of different individuals do not always allow them to be identified with sufficient accuracy as representatives of a particular species category.

The very concept of the species is changing, supplemented by new aspects of biological, geographic and ecological properties. Of course, the physiological characteristics of living organisms continue to occupy a special place, which form the basic set of characteristics for the formation of systematics. Difficulties in classification usually arise when new forms are discovered, which stand in intermediate links between different species.