The main directions of evolution.

The origin of life and its development from ancient times puzzled scientists.People have always tried to get close to these mysteries, to make the world, thus more understandable and predictable.Many centuries dominated point of view of the divine universe and the beginning of life.The theory of evolution has won a place of honor as the main and the most probable versions of all life on our planet long ago.The main provisions formulated by Charles Darwin in the middle of the XIX century.The ensuing century gave the world a lot of discoveries in genetics and biology, which made it possible to prove the validity of Darwin's theory, to expand it, to merge with the new data.So a synthetic theory of evolution.It absorbed all the ideas of the famous explorer and the results of scientific research in various areas from genetics to ecology.

From individuals to class

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

initial stage of reforms, eventually leading to the emergence of a new kind - is microevolution.Such changes over time accumulate and end with the formation of a new higher level of organization of living beings, genus, family, class.Education supra structures called macroevolution.

Similar processes

Both levels are basically the same flow.The driving forces and micro and makroizmeneny is natural selection, isolation, heredity, variation.A significant difference between the two processes is that between different species is practically impossible crossing.The result is a macro-based interspecific selection.A huge contribution to making microevolution free exchange of genetic information between individuals of the same species.

convergence and divergence signs

main directions of evolution can occur in several forms.A powerful source of the diversity of life - a sign of the divergence.It operates within a particular species, and at higher levels of the organization.The environment and natural selection leads to the separation of one group of two or more different specific features.At the level of species divergence may be reversible.In this case, the population of newly formed merge into one.At higher levels, the process is irreversible.

Another form - phyletic evolution, implying transformation of the form, without isolation of individual populations within it.Each new group is a descendant of the previous and subsequent ancestor.

significant contribution to the diversity of life and making a convergence or "toe-in" features.In the process of unrelated groups of organisms, influenced by the same environmental conditions, individuals have formed similar bodies.They have a similar structure, but different backgrounds and perform virtually the same function.

very close to the convergence of parallelism - a form of evolution, when the original diverging group developed in a similar way under the influence of similar conditions.Convergence and parallelism shared fairly fine line, and it is often difficult to attribute the evolution of a particular group of organisms to one form or another.

Biological progress

main directions of evolution was first described in the works of ANSevertsov.He offered to provide the concept of biological progress.The work of scientists set out ways to achieve it, and the main path and the direction of evolution.Ideas developed Severtsov IIShmal'gauzen.

main directions of evolution of the organic world, isolated by scientists - is biological progress, regression and stabilization.By title easily understand how these processes differ from each other.Progress leads to the formation of new features that increase the degree of adaptation to the environment.Regression is expressed in the reduction of the number of the group and its diversity, leading eventually to the extinction.Stabilization involves consolidation of acquired characteristics and their transmission from generation to generation in a relatively constant conditions.

In a narrower sense, denoting the main lines of organic evolution, it implies biological progress and its forms.

There are three main ways to achieve biological progress:

• arogenez;
• allogenez;
• katagenesis.

arogenez

This process makes it possible to increase the overall level of the organization as a result of the formation of aromorphosis.We offer to find out what is meant by this concept.For aromorphosis - direction of evolution, leading to a qualitative change in living organisms, accompanied by their increasing complexity and increasing adaptive properties.As a result of changes in the structure becomes more intense functioning of individuals, they are able to use new, previously untapped resources.Consequently organisms become in some sense, free from environmental conditions.At a higher level the organization of their adaptations are largely universal, giving the ability to develop, regardless of ambient conditions.

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

Aromorphosis by Severtsov, is a relatively rare evolutionary event.It marks the morphophysiological progress, which, in turn, initiates the progress of general biological, accompanied by a significant expansion of the adaptive zone.

Social aromorphosis

Considering the direction of evolution of the human race, some researchers introduced the concept of "social aromorphosis."They are denoted by universal changes in the development of social organisms and their systems, leading to a complication of greater adaptability and increasing mutual societies.The number of such aromorphoses includes, for example, the emergence of the state, printing and computer technology.

allogenez

During biological progress are formed and change under global.They are the essence of allogenez.This direction of evolution (table shown below) is a significant difference from aromorphosis.It does not increase the level of organization.The main consequence of allogenez - it idioadaptation.In fact, it is a particular change, due to which the body are able to adapt to certain conditions.This line of organic evolution allows similar species live in very different geographic areas.

expressive example of such a process - a family of wolves.Its species are found in various climate zones.Everyone has a certain set of adaptations to their environment, while not significantly outperforming any other kind of level of organization.

Scientists identify several types idioadaptatsy:

• shape (for example, streamlined body waterfowl);
• color (here is mimicry, preventive and protective coloration);
• reproduction;
• on movement (ear waterfowl, birds of the air bag);
• adaptation to environmental conditions.

differences aromorphosis and idioadaptation

Some scientists disagree with Severtsov and do not see sufficient reason for distinguishing idioadaptatsy and aromorphoses.They believe that the extent to which progress can be assessed only after a considerable time after the change occurs.In fact difficult to understand how evolutionary processes to lead a new quality or developed ability.

Severtsov followers are inclined to think that it should be understood by idioadaptatsy transform body shape, excessive development or reduction of.Aromorphoses also represent substantial changes in embryonic development and formation of new structures.

Catagenesis

Biological evolution can proceed with the simplification of the structure of organisms.Maturation - the total degeneration process that leads to a decrease in the organization of living beings.The main result of the evolution of this trend (table comparing the three ways listed below) is the appearance of so-called primitive katamorfozov or signs that are replacing lost progressive.Examples of organisms that have passed phase of the general degeneration may be any parasite.For the most part, they lose the ability of independent travel, they have greatly simplified the nervous and circulatory systems.But there are various means for a better introduction into the host body and attachment to the appropriate authorities.

ratio

main directions of evolution are interrelated and in the course of history constantly replace each other.After the fundamental changes in the form aromorphosis or degeneration comes a time when a new group of organisms begins to delaminate due to the development of its individual parts of different geographic areas.Starts evolution by idioadaptatsy.After a time, the accumulated changes lead to a new qualitative leap.

direction of the evolution of plants

modern flora not appear immediately.Like all organisms, it has gone a long way of development.The evolution of plants included the acquisition of several important aromorphoses.The first of these was the emergence of photosynthesis that allowed primitive organisms use the energy of sunlight.Gradually, as a result of changes of morphology and photosynthetic properties of any algae.

The next step was the development of the land.For the successful passage of the "mission" took another aromorphosis - differentiation of tissues.There mosses, spore plants.A further complication of the organization due to the conversion process and method of reproduction.Such aromorphoses as ovule, pollen grains, and finally, the seed is characterized by gymnosperms, evolutionarily more advanced than the spore.

further ways and directions of evolution of plants moving towards even greater adaptation to environmental conditions, increasing resistance to unfavorable factors.The emergence of a pestle and germ layer formed flowering plants, or angiosperms, are today in a state of biological progress.

Animal Kingdom

evolution of eukaryotic (eukaryotic cell contains a nucleus decorated) with the heterotrophic type of feeding (heterotrophs not create organics using chemo- or photosynthesis) are 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 two layers, ecto- and endoderm.At the round and flat worms structure is complicated.They are characterized by the third embryonic leaf, the mesoderm.Aromorphosis This makes it possible to further differentiation of tissues and organs of the appearance.

next step - the formation of a secondary body cavity and further dividing it into sections.Annelids already have parapodia (primitive type of course) as well as the circulatory and respiratory systems.Convert parapodia in jointed limbs and some other changes has led to the emergence of the type of arthropods.Even after landfall began to actively develop the insects due to the emergence of embryonic membranes.Today they are most adapted to life on earth.

Such large aromorphoses as the formation of the notochord, neural tube, the abdominal aorta and heart, made possible the emergence of the type of chord.Thanks to a number of progressive changes in the diversity of living organisms replenished fish, reptiles and amniotes.The last of the presence of embryonic membranes are no longer dependent on the water and came to the land.

Further evolution is moving towards the transformation of the circulatory system.There are warm-blooded animals.Adaptation to the flight made possible the emergence of birds.Such aromorphoses as a four-chambered heart and the disappearance of the right aortic arch, the increase in the forebrain and cortical development, the formation of the coat and breast and a number of changes have led to mammals.Among them stood out in the evolution of placental animals, and today is in a state of biological progress.

direction of evolution of the human race

question of the origin and evolution of the ancestors of modern humans studied until thoroughly.Thanks to the discoveries of paleontology and comparative genetics changed the already established ideas of our "pedigree."Even 15 years ago it predominated view that the evolution of hominids walked along a linear type, that is comprised of successive more and more advanced forms: Australopithecus, Homo habilis, archanthropines, Neanderthal (paleanthropic) neanthropines (modern man).The main directions of the evolution of man, as is the case with other organisms, leading to the formation of new adaptations, raising organization.

data obtained in the last 10-15 years, however, have made significant adjustments to the already existing picture.New finds and refined dating indicate that the evolution was more complex.Hominin subfamily (refers to the family of hominids) appeared to consist of almost twice the number of species than previously thought.Evolution was not wearing his linear and contained several simultaneously develop lines or branches, progressive and deadlock.At various times coexisted with three or four or more species.Narrowing this diversity was due to the displacement of an evolutionarily more advanced groups of other, less developed.For example, it is now generally accepted that Neanderthals and modern humans lived at the same time.First were our ancestors, but it is a parallel branch, which replaced the more advanced representatives of hominin.

Progressive changes

Doubtless remain the main aromorphoses that led to the prosperity of the subfamily.This bipedalism and increase brain.The reasons for the formation of the first scientists disagree.For a long time it was thought that it was a necessary measure necessary for the development of open spaces.However, recent data suggest that human ancestors walked on two legs in the period of life in the trees.This ability to have appeared immediately after separation from the chimpanzee line.According to one version hominin initially moved like modern orangutans standing with both feet on one branch and holding hands on the other.

brain growth took place in several stages.