The smallest taxon (a category in biology) is called a species. A species is a group of individuals that have similar morphological features, interbreed freely and at the same time give fertile offspring. There are other, more extensive taxa. A group of closely related species, for example, forms a genus, and from closely related genera a family is obtained, and so on. But today we will talk about the smallest taxonomic category, that is, the species. What is a species, how is this taxon formed, and what methods of speciation exist in nature? So let's get started.
Speciation in nature
Speciation is the process of formation of new species and their change. There is such a thing as a barrier of interspecies compatibility. What is it?
This is the case when species, when crossed, do not have the ability to produce fertile offspring. According to the theory of evolution, speciation depends on hereditary variability. Today in biology there are two types of speciation - geographical and ecological. Let's talk about each of them in more detail.
Geographic speciation
Geographical, or, as it is also called, allopatric speciation, is the formation of new species in spatial isolation. Simply put, the formation of a species comes from populations living in different geographical areas. Since populations are separated for a long time, genetic isolation occurs between them.
It persists even if populations are no longer segregated. Many examples of geographic speciation can be cited. Let's take the May lily of the valley as an example. It has five independent areas at once, which at first were considered one. It is important that they are all at a fairly large distance from each other. Races appeared in each of the territories, which led to the formation of independent plant species. Also, using the example of migration, consider the resettlement of the great tit. This species, which lives in Europe, began to settle closer to the east. For this there were northern and southern routes. Closer to the south, such subspecies as Bukhara and small tits were formed, closer to the north - small and large. The latter do not produce hybrids.
So it happened that as a result of such settlement, a reproductive barrier arose between them. Let's consider one more example. An old species of Australian parrot existed in South Australia. It is worth noting that this is a rather humid area. With the onset of drought, the area changed, as a result of which the territory was divided into two parts:east and west. Naturally, for a long time, different types of parrots have formed on each of them. After a long time, the original area was practically restored. Climatic conditions again became the same, but once a single species could no longer interbreed, as genetic isolation occurred. Thus, allopatric speciation is associated with isolation. As a result, new independent species are formed.
Ecological pathway of speciation
There is another way besides the geographical one. This is ecological speciation. It also has a second name - sympatric. What is this method? Ecological speciation is the formation of new species as a result of the divergence of individuals in separate territories. That is, at the beginning, the species lives in one area, and later, due to increased competition, it settles in other territories. For example, you can observe the following situation. Large rattle blooms all summer. But if every year in the middle of summer the grass is mowed in this area, then the plant will no longer be able to produce seeds. For this reason, seeds that were given before or after mowing are preserved.
Thus, both types in the same meadow cannot interbreed. Ecological speciation can be confirmed by the presence of closely related species in adjacent ranges. Sometimes these areas even coincide.
Speciation and its role
Methods of speciation have been studied for a long time, but the study is rather difficult. This is due to the duration of the speciation process. Ecological and geographical speciation are very different from each other, nevertheless, each of them has a certain significance in the life of nature. Their main role is the formation of new species.
