The main directions of evolution. Evolution of plants and animals

The origin of life and its development from ancient times has puzzled scientists. People have always tried to approach these mysteries, making the world, thus, more understandable and predictable. A century dominated a point of view about the divine Universe and life. The theory of evolution has won a place of honor the main and most probable version of the development of all life on the planet relatively recently. Main provisions it was formulated by Charles Darwin in the mid-nineteenth century. The ensuing century has given the world a lot of discoveries in genetics and biology that made it possible to prove the validity of Darwin's theory, extend it to merge with the new data. So there was synthetic theory of evolution. She absorbed all the ideas of the famous Explorer and the results of scientific research in various fields from genetics to ecology.

From specimen to class

Biological evolution is a historical development of organisms, based on the unique processes of functioning of genetic information in certain environmental conditions.

The Initial stage of such transformation, eventually leading to the emergence of new species, — this is microevolution. Such changes over time accumulate and end up forming a new higher level of organization of living beings: genus, family, class. The formation of supra-structures is called macroevolution.

Accounting processes

Both levels basically flow the same. Driving forces and micro-and macrohistory are natural selection, isolation, heredity, variation. A significant difference between the two processes is that between different types of crossing are virtually eliminated. As a result, in the basis of macroevolution lies interspecies selection. A huge contribution to the microevolution makes the free exchange of genetic information between individuals of the same species.

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Convergence and divergence characteristics

The Main directions of evolution can occur in several forms. A powerful source of diversity of life — is a divergence of signs. It acts as a specific and at higher levels of the organization. Environmental conditions and natural selection lead to the division of one group into two or more having particular characteristics. At the species level divergence may be reversible. In this case, the resulting population again merge into one. At higher levels the process is irreversible.

Another form — methodology in phyletic evolution, involving the conversion of no allocation inside individual populations. Each new group is a descendant of the preceding and ancestor for later.

A Significant contribution to the diversity of life contributes to the convergence or “convergence” signs. In the process of development unrelated groups of organisms, influenced by the same environmental conditions, the species formed similar bodies. They have similar structure but different origin and perform virtually the same function.

To convergence very close parallelism - a form of evolution where initially diverging groups develop in a similar way under the influence of identical conditions. Convergence and parallelism of parts is quite a fine line, and it is often difficult to attribute the evolution of a particular group of organisms to one form or another.

Biological progress

The Main directions of evolution were first set out in the writings of A. N. Severtsov. He suggested the concept of biological progress. In the work of scientists set out how to achieve it, and also the main ways and directions of evolution. Ideas developed Severtsov and I. I. Schmalhausen.

The Main directions of evolution of the organic world, dedicated scientists, — it is a biological progress, regression, and stabilization. Names easy to understand how these processes differ from each other. Progress leads to the formation of new characteristics that increase the degree of adaptation of the organism to the environment. The regression is expressed in the reduction of the size of the group and its diversity, ultimately leading to extinction. Stabilization entails the consolidation of acquired characters and their transmission from generation to generation in a relatively unchanging environment.

In the narrower sense, denoting the main areas of organic evolution, imply that biological progress and its forms.

There are three main ways of achievement of biological progress:

• Orogenes;
• Allogenes;
• Catagenesis.

Aerogenes

This process makes it possible to improve the General level of organization as a result of the formation of aromorphosis. Offer to find out what is meant by this concept. So, anamorphs — the direction of evolution, leading to a qualitative change in living organisms, accompanied by their complication and increase adaptive properties. As a result of changes of the structure becomes more intense functioning individuals, they have the opportunity to use new, previously untapped resources. As a consequence, organisms have become, in a sense, free from the environment. At a higher level of organization of their fixtures are of a substantially universal nature, giving the ability to develop whateverenvironment.

A Good example of aromorphosis is the transformation of the circulatory system of vertebrates: the emergence of the four chambers of the heart and the separation of the two circles of blood circulation - large and small. Plant evolution is characterized by a significant leap forward as a result of formation of the pollen tube and the seed. Aromorphoses lead to the appearance of new taxonomic units: classes, divisions, types and kingdoms.

Aroports, Severtsova, is a relatively rare, evolutionary phenomenon. It marks the morphophysiological progress which in turn initiates the biological progress, accompanied by a significant expansion of the adaptive zone.

Social anamorphs

Considering the directions of evolution of the human species, some scientists have introduced the concept of ‘social aroports”. They indicated universal changes in development of social organisms and systems, leading to complication, the greater adaptability and the increasing interdependence of societies. The number of such aromorphoses include, for example, the emergence of the state, typography and computer technology.

Allogenes

In the course of biological progress are formed and changes less global in nature. They are the essence of allogenes. This direction of evolution (table given below) there is a significant difference from anamorfose. It does not increase the level of organization. The main consequence of allogenes — it's idiazabal. In fact, it represents the frequent changes through which the organism receives the possibility to adapt to certain conditions. This direction of evolution of the organic world allows the closest species to live in very different geographic areas.

Expressive example of such a process — the family of the wolf. Its species are found in various climatic zones. Everyone has a certain set of adaptations to its habitat, while not significantly superior to any other kind of organization.

Scientists distinguish several types of videoadapters:

• On the form (e.g., streamlined body waterfowl);
• Colour (this includes mimicry, warning and cryptic coloration);
• Reproduction.
• Movement (membrane waterfowl, air bag birds);
• Adaptation to environment.

Differences aromorphosis and idiazabal

Some scientists do not agree with Severtzovi and do not see sufficient reasons to distinguish videoadapters and aromorphoses. They believe that progress can be assessed only after a considerable time after the appearance of changes. In fact it is difficult to understand how evolutionary processes will lead to a new quality or a developed capacity.

The followers of the Severtsov inclined to think that under videoadapters to understand the transformation of the shape of the body, excessive development or reduction of organs. Anamorfosi also represent significant changes in embryonic development and the formation of new structures.

Catagenesis

Biological evolution can proceed with the simplification of the structure of organisms. Catagenesis — a General degeneration process that leads to the decline of the organization of living beings. The main result of this direction of evolution (table, comparing the three ways given below) is the emergence of so-called metamorfoza or primitive signs, which are replacing the lost progressive. Example of organisms that have passed the stage of total degeneration, can be any parasite. For the most part they lose the ability for independent movement, they have greatly simplified the nervous and circulatory system. But there are a variety of tools for better implementation in the body of a host and application to appropriate authorities.

Value

The Main directions of evolution are interrelated and in the course of historical development constantly replace each other. After fundamental changes in the form of aromorphosis or degeneration there comes a time when a new group of organisms begins to delaminate as a result of its separate parts in different geographicalzones. Evolution begins by videoadapters. After a time, the accumulated changes lead to a new qualitative leap.

Direction of evolution of plants

The Modern flora did not appear immediately. Like all organisms, it has passed a long way of formation. Evolution of plants included the acquisition of several important aromorphoses. The first of these was the emergence of photosynthesis, which enabled primitive organisms to use the energy of sunlight. Gradually as a result of transformations of the morphology and photosynthetic properties of the algae occurred.

The Next step was the development of the land. For successful completion of the “mission”, I took another aroports — differentiation of tissues. Appeared in mosses, spore-bearing plants. The increasing complexity of organization is associated with the transformation process and methods of reproduction. Such aromorphosis as semjazachatki, pollen grains, and, finally, the seed of gymnosperms describe plants that are evolutionary more advanced than spore.

Next, the ways and directions the evolution of plants moving in the direction of greater adaptation to the environment, increase resilience to adverse factors. The result of the appearance of the pistil and germ layer formed flowering or angiosperms, are today in a condition of biological progress.

Animal Kingdom

Evolution of eukaryotes (eukaryotic cell contains the core) with heterotrophic type of nutrition (heterotrophs are not able to create organic substances through chemo - or photosynthesis) is also in the early stages was accompanied by differentiation of tissues. Coelenterates have one of the first significant aromorphoses in the evolution of animals: embryos are formed in two layers, ecto - and endoderm. From round and flat worms, the structure is complicated. Typical for them is the third piece of the embryo, the mesoderm. This aromaros makes it possible for further differentiation of tissues and the appearance of bodies.

The Next step — the formation of a secondary body cavity, and further division into departments. Annelids already have parapodia (a primitive type of limb), as well as the circulatory and respiratory systems. Conversion parapody in jointed limbs and some other changes have resulted in the emergence of the phylum Arthropoda. After their landfall began to actively develop in insects due to the appearance of embryonic membranes. They are more adapted to life on earth.

Such large aromorphoses as the formation of the chord, neural tube, abdominal aorta and heart, and has made possible the emergence of a type of Chordate. Due to a number of progressive changes, the diversity of living organisms was supplemented with fish, amniotomy and reptiles. The latter due to the presence of embryonic membranes ceased to depend on water and walked on land.

Then the evolution goes the way of the conversion of the circulatory system. Arise warm-blooded animals. Adaptation to flight has made possible the emergence of birds. Anamorfosi such as a four-chambered heart and the disappearance of the right aortic arch, increased forebrain hemispheres and the development of the cortex, the formation of the coat and mammary glands and a number of changes led to the emergence of mammals. Among them, in the process of evolution separated placental animals, and today in the condition of biological progress.

Directions of evolution of the human race

The question of the origin and evolution of the ancestors of modern humans is not yet studied thoroughly. Thanks to the discoveries of paleontology and comparative genetics has changed prevailing ideas about our ‘pedigree". 15 years ago predominated the view that the evolution of hominids was in the linear type, that is comprised of a series of successive all the more developed forms: Australopithecus, Homo habilis, arhantrop, Neanderthal (paleoanthro), neoanthrope (modern man). The main directions of the evolution of man, as in the case with other organisms, led to the formation of new adaptations, to improve the level of organization.

The Data obtained in the last 10-15 years, however, have made significant changes to the existing pattern. New discoveries and refined Dating suggests that evolution was more complex. Subfamily Hominini (belongs to the Hominid family) was composed of almost twice the number of species than previously thought. The evolution of his were not of a linear character, and contained at the same time developing several lines or branches, and a progressive dead end. At different times coexisted together three or four or more types. Contraction of this diversity occurred because of the displacement of evolutionary more developed groups of other less developed countries. For example, it is now generally accepted that Neanderthals and modern humans lived simultaneously. The first were not our ancestors, but was a side branch that replaced the more developed representatives of hominines.

Progressive change

Doubtless remain the main aromorphoses, which led to the prosperity of the subfamily. It is bipedalism and increase in brain. About the reasons for the formation of the first scientists disagree. For a long time it was thought that this was a necessary measure required for the development of open spaces. However, recent data allow us to assert that the ancestors of humans walked on two legs once in the period of life in the trees.This ability came to them immediately after the separation from the chimpanzee line. According to one version hominini initially moved like modern orangutans, standing with both feet on one branch and grabbing on to another.

The growth of the brain took place in several stages. First it started with Homo habilis (skillful man), who learned to make simple tools. The growth of the brain coincided with the increase in the share of meat in the diet hominines. Ability, apparently, were scavengers. Following the enlargement of the brain was also accompanied by an increase in the number of meat-eating and the resettlement of our ancestors outside of the African continent. Scientists suggest that the increase in the share of meat in the diet is associated with the need to make up the cost of energy going to maintain the increased work of the brain. Presumably, the next stage of this process coincided with the development of the fire: cooked food is not only quality, but also calories, in addition, significantly reduced the time required for chewing.

The Main directions of evolution of the organic world, through the centuries, shaped the modern flora and fauna. The movement of the process towards adaptation to changing environmental conditions has led to a huge diversity of life forms. The main directions of evolution are the same at all levels of the organization, as evidenced by the data of biology, ecology and genetics.