There are not many left in the world of people whocontinue to believe in the biblical story of the creation of all life on our planet. Everything is familiar with the concept of evolution. Multiple evidence of the development of all living things on Earth leaves no doubt about the origin of the changes in the world around us. Who is Charles Darwin, even younger schoolchildren know. But when it comes to what is the result of evolution, there is no definitive answer.
We begin, in fact, with the definition of the conceptevolution in biology. This word is derived from the Latin evolutio, which means literally "deployment". The process of evolution is often represented in the form of an unfolding spiral. In biology, this term refers to the irreversible process of development of the organic world in all aspects of its manifestation. The result of evolution is the diversity of the organic world and the improvement of the adaptability of organisms to environmental conditions.
The founder of the exercise - Charles Darwin (1809-1882) - formulated the following principles of evolutionary teaching:
Since the results of evolution, according to Darwin,is the fitness of the organism, as a result of the action of natural selection, individuals that possess the most useful qualities for survival survive and thrive. Natural selection is the "creative" mechanism of evolution. The result is the appearance of new signs that increase the chances of the individual to leave prolific offspring and pass on to them these signs.
If the result of evolution isfitness and variety of species, then the material for it are mutations and combinative variability within the genome. It is the mutations that cause the appearance of new signs that creatively assess the natural selection for suitability and necessity in the specific habitat of the species. Genetic variability and fluctuations in the numbers of individuals in populations (population or life waves) provide material for incorporating mechanisms for the struggle for survival and survival of the fittest.
The struggle for existence as a consequencenatural selection leads to the fact that the result of evolution is the emergence of new species from the ancestors. And natural selection can go in three directions:
Whatever way evolution proceeds, the mainthe condition for the formation of new species is reproductive isolation - the impossibility of the free crossing of individuals for panmictichnyh species (sexually reproduced). It should be said that the achievement of reproductive isolation in nature follows two paths: allopatric (reproductive isolation is achieved by geographical separation of populations) and sympatric (isolation occurs on the same range with the maternal species). In any case, as soon as the regime of impossibility of free crossing is established between populations, one can say that the result of the evolution of the organic world is the formation of a new species, and this process is completed.
As soon as the sign changes appear ingenome, they are tested by natural selection. The most successful are fixed morphologically and become adaptive. There are many examples in nature. Successful morphological devices include patronizing and cautionary coloring, masking and passive protection. Protective coloration, such as white plumage in a partridge in winter, makes animals invisible against the backdrop of the environment. Warning organisms have those organisms that have in their arsenal chemical means of protection against enemies. For example, the red-black coloring of poisonous tree frogs or yellow-black in poisonous salamanders. Disguise as protection against enemies can be truly passive (the shape of the body of a stick insect really resembles a wand) or imitative (for example, the belly of a butterfly-glass bowl is very similar to the belly of wasps, so the birds don’t touch it).
All evolutionary scientists agree with the statementthat the nature of fitness is relative. There are no absolutely useful signs, as there are no absolutely useless ones. All adaptations are produced in specific environmental conditions and, if they change, may be useless or even harmful. Protection from one enemy can be useless when protecting from another (most birds do not eat stinging wasps and hornets, but flycatchers and bee-eaters mainly feed on them). Behavioral features may be meaningless (for example, maternal instinct, which causes the starling to feed the cuckoo). A useful organ or skill in other conditions becomes a burden (for example, a flying fish jumps out of the water and escapes from aquatic predators, but becomes an albatross prey).
About 7.5 million animal species, about 300thousands of plant species and 600 species of fungi, add 36 thousand species of unicellular organisms - all this diversity is the main result of the evolution of life on planet Earth. And they are all perfectly adapted to the conditions of their habitat. Over 3.7 million years of life on the planet, living organisms have constantly evolved and adapted to environmental conditions, and the process continues today.
