Paleontology has proved that many of the past species have disappeared completely.
Progress and setbacks in nature - the concept of opposites.In the first case is the development and distribution of species on the planet.Biological evolution is a movement of regression, characterized by the reduction of habitat, reduction in number of individuals due to maladjustment.This process is accompanied by a decrease in the amount of one group of species due to the pressure on them the other, as well as the disappearance of species.
biological regression is mainly due to the loss of the ability of organisms to adapt to the changing environment.
This movement is characteristic of parasitic organisms, birds and creatures still living in caves or underground.
biological regression can be considered an example of parasites - flatworms.In the process of the return of their simpler sense organs, digestive system, nervous system.At the same time there are different devices (slinging, suction cups, etc.) required for retention in the gut of the host.For example, female crustaceans, leading a parasitic way of life, completely lost all signs of arthropods, retaining only the function of laying eggs.A parasite in the human body is able to produce bovine tapeworm about eleven billion eggs, which ensures the protection of the host body.Therefore, these are considered the most prolific worms.
biological regression peculiar and plants.Just as in living organisms and their reverse development is closely associated with parasitism.For example, there is a plant broomrape.It is a parasite on the root system of sunflower, clover, hemp.Broomrape has darkish stems, and its scale-like leaves contain chlorophyll.They are introduced into the stem of another plant by means of suction cups and suck the host's body nutrients.
For animals, preserving stillness throughout life, body movement is entirely during the larval stage.Chord have reduced.These organisms, in particular, relates Pogonophora - representative of a particular type of brahiata.These individuals do not really look like animals.They live on the seabed and still live.Pogonophora has the heart and the brain, however, the stomach, and her mouth is reduced.The tentacles are the respiratory organs.Inside they have long hairs, equipped with blood vessels.They gradually accumulate microorganisms.When they (microorganisms) becomes much Pogonophora pulls hairs inside.Under the influence of special enzymes, micro-organisms are digested and absorbed in the internal growths.The presence of embryonic intestine proves the existence of this body in the ancestors pogonophores.But due to the fact that the digestion process is performed outside the organism, the digestive tract organs became reduced.
Regression animals living underground or in caves, we can consider the example of Proteus.It is representative of the class of amphibians, like a newt.It lives in the caves of this animal.On his head both sides it has external gills.Proteus can breathe and in the water and on land.In the first case he uses the gills and in the second - the lungs.Since Proteus lives in the deep cave, it has a serpentine shape.The body had a clear, colorless, has no pigments.In adults, representatives of bodies covered with skin, the larvae have rudimentary eyes.There on the body of Proteus and two pairs of limbs underdeveloped.
as the genetic basis of evolutionary changes that lead to a simplification of the organizational level, the mutation acts.
in the development of the organic world stands three directions.Aromorphosis characterized by an increase in the level of organization of organisms.Idioadaptatsy is an adaptation to the environment without fundamental changes in the biological structure.The total degeneration is a simplification of the level of organization of living beings.
