This article will discuss the process of speciation, you will find examples, a description here , and learn more about species of living things. What is this, consider below.
What is the essence?
Speciation is the process of formation and change of new species.
It is also a very complex process of evolution and the emergence of a new species, which terminates any communication with their parents and turns into a special, unique community of organisms.
The essence of speciation is to change organisms, the main force of the phenomenon is considered to be natural selection and reproductive isolation.
There are several types of speciation: allopathic, the process of which proceeds slowly and smoothly, in contrast to another species, sympatric. It can proceed at different speeds, but most often - randomly and jerkily. Charles Darwin believed that the extinction of intermediate forms and the survival of the extreme as a manifestation of competition is this process. The stages of speciation throughout the creation of a new subject alternate with strict sequence, creating a chain of newly introduced qualitative parameters, data that will highlight a specific population or individual as a representative of a new species.
Speciation forms
Divergent speciation is the primary division of a whole species into several new ones. The main effect of this is the accumulation of various changes at the genetic level and the disappearance of reproductive function.
Phyletic speciation is a metamorphosis mechanism in which one species transforms into another, new. The main process is that when the climatic conditions of the environment change, the best changes are acquired in the entire population. By hybridization, different species are crossed in their habitat.
The emergence of one or more new species is subject to two main mechanisms: allopatric and sympatric. The sequence of speciation largely depends on a wide variety of factors corresponding to the form of emergence of a new individual.
The mechanics of sympatric speciation
Sympatric (ecological) speciation is the emergence of a new subject among the standard set of individuals in the form, it appears inside the old habitat. This isolation process is called genetic.
Sympatric (ecological) speciation is a phenomenon that occurs in a certain area and depends on the appearance in the population of certain independent groups that do not have the ability to interbreed. This option is the fastest, it gives rise to species that are closest to the initial one. This is a process of speciation, as a result of which individuals of one species intensify the struggle for existence within the limits of old habitats, without expansion.
Allopatric (geographical) speciation
Allopatric speciation occurs when isolation of habitats and the presence of differences in the climate of living within a particular species. For parasites, this pathway is characterized by the search and development of new hosts. Studies of the genetic composition and interchromosomal differences between humanoid primates and humans give the right to suggest that their separation occurred sympatrically. Where reproduction occurs sexually and there is no geographical isolation, sympatric speciation is extremely rare. New modifications can spread in the population or end with the death of the carrier, if there is no possibility of reproduction. Allopathic speciation occurs rather slowly, hundreds of thousands of generations may appear in the process of change, the peculiarity is the aggravation of the struggle for existence and new territories of residence.
“Instant” polyploidy-based speciation
Where reproduction occurs asexually (as in various plants), one individual, significantly different from the rest, is enough to become completely genetically isolated and to begin a completely new species.
Options for sympatric speciation are polyploidy and hybridization.
Polyplodia - the so-called type of mutation, when there is an increase in the presence of chromosomes in living cells, it always occurs a multiple number of times. For example, completely different types of wheat form a line with the number of chromosomes 14, 28, 42. The wild cotton cells contain 26 chromosomes, and its cultural counterpart already 52. Hybridization is the process of crossing and obtaining new hybrids, the essence of which is to combine genetic material in the cells of an individual.
Speciation observation
Hybridization - the crossing of organisms of different species, that is, the union of various genomes in one individual (hybrid). One of the common examples of hybridization is a cultural plum, which was obtained through the union of cells of thorns and cherry plum. Also in this group we can mention the mountain ash crab, whose range of existence is the taiga of central Siberia.
Speciation Examples
Rhagoletis pomonella pied-winged apple flies is one of the most striking examples of speciation. In the process of their evolution, the existence of this species was not shared by physical barriers. Initially, the range of existence of these flies was the eastern coast of the United States of America. These flies existed in the fruits of hawthorn, however, with the beginning of the colonization of the United States and the introduction of new crops to this territory, including the apple tree in 1647, new niches and habitats appeared. But only in 1864, Rhagoletis pomonella was fixed on apple fruits, which indicated the appearance of a completely new species. During long observations, the development paths of species were divided.
Representatives do not interbreed with each other, since each race prefers its own type of fruit for mating. Due to the different flowering period of plants, this process becomes simply impossible.
The types of speciation in the division of the old into several new scientists have identified in two main types of this process: allopathic and sympatric.
Island speciation
Since the islands are an isolated system where conditions arise for the development of flora and fauna groups separate from the mainland, species are able to acquire new properties and features. If on the mainland adaptation to climate was not necessary for existence and survival, an easier way of survival - migration was preferable. On the islands, environmental adaptability is a must.
In the mainland, animals throughout the entire evolutionary period could move to different climatic zones, move together with glaciers. The species existing on the islands had to adapt to local climatic conditions - this was the key to survival.
These features of existence have formed on the islands many species of unusual animals. Unfortunately, most of this amazing animal world has disappeared, all thanks to human intervention. Hunting, the importation of rodents, bacteria and infections led to the mass extinction of rare amazing species. At a time when the human foot had not yet set foot on the wild islands, each of them had its own, completely unique and not like the other world. Before the appearance of man, species living on the islands could migrate to the mainland only with a change in water level or with global changes in geological position. The cause of migration could also be disasters that violate the isolation of the island. As a result of such changes, both island and continental animal species were able to migrate in both directions. In most cases, with such movement and when continental species hit the island, island residents were threatened with complete extinction. Although there were cases when local species adapted to new conditions and competed with new ones that arrived from the mainland.
Peripheral Isolators
Paleontologists quite rarely find remains that would belong to the ancestors of modern animal species. The island origin makes it possible to assume that the currently existing species of flora and fauna were originally separated and existed in limited populations. Because of their size, these populations could not find opportunities to search for new places, and the island itself may have ceased to exist over time.
Not all animal species began to exist on the islands, which is the most common condition for geographical isolation.
The value of peripheral isolators
The bottom line is that new species arise in an environment completely isolated from the outside world and small populations. The entry of a small population of individuals into a wider habitat will certainly lead to the extinction of the population, but new organisms emerge from the percentage of subjects who are able to adapt to new conditions.
Species that manage to survive emerge from small populations, engaging in a struggle for dominance with dominant forms of life, and not with the slow transformation of existing ones. If the dominant species do not withstand contractions, then new forms begin to grow. The process of creating life spans billions of years, during which time continents appeared and disappeared, water levels changed, the climate became hotter or colder. Species and populations of animals were constantly divided and connected with each other, various barriers between them formed and disappeared.
Natural changes and global catastrophes, such as the fall of a meteorite, were a conductor of evolution and modification. Constant changes in the habitat of the species forced them to adapt to changing conditions. A huge number of organisms failed. Those who were able to adapt settled and seized new territories for existence. Unlike land, the world's oceans are the largest and most stable environments in the world, in which there are billions of different creatures and organisms. There are practically no natural barriers in it, relatively few new forms of life are formed.
Over the past few hundred billion years, a global event for the oceans has been the emergence of a fairly hardy and resistant to various changes in species of marine reptiles. In further development, marine mammals and many species of seabirds appeared.
Currently, the main negative event has been the increase in human presence in the oceans: dumping of household, construction, industrial and radioactive waste, uncontrolled fishing of various species of fish, complete extermination of some species of marine predators and large mammals. The consumer impact of man on the oceans can lead to global catastrophe and the extinction of many marine species.