There are not many people left in the world who continue to believe in the biblical story of the creation of all life on our planet. Everyone is familiar with the concept of evolution . Multiple evidence of the development of all life on Earth leaves no doubt about the origin of changes in the world around us. Who is Charles Darwin, even younger students know. But when it comes to what is the result of evolution, there is no single answer.
Academic background
We begin, in fact, with the definition of evolution in biology. This word is derived from the Latin evolutio, which literally means "deployment." The evolutionary process is often portrayed in the form of a developing spiral. In biology, this concept 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.
Darwinism as the basis of the doctrine of evolution
The founder of the doctrine, Charles Darwin (1809-1882), formulated the following principles of evolutionary doctrine:
- All species are capable of unlimited reproduction of their own kind.
- Lack of life-supporting resources limits the unlimited growth of the species. Natural selection as a result of evolution is the limiter that regulates the number of organisms.
- Success, as well as the death of an individual in the struggle for existence, is selective. And it was precisely this selectivity that he called natural selection.
- According to Darwin, the main results of evolution are the improvement of the organism's fitness for biotope conditions and, as a result, an increase in the diversity of species.
Diversity as a consequence
Since the results of evolution, according to Darwin, are the fitness of the organism, as a result of the action of natural selection, individuals with the qualities that are most useful for survival survive and thrive. Natural selection is a "creative" mechanism of evolution. The result is the emergence of new traits that increase the chances of the individual to leave the prolific offspring and pass on these traits to him.
Evolution material
If evolution results in fitness and diversity of species, then mutations and combinational variability within the genome serve as material for it. It is mutations that cause the emergence of new traits that creative selection will naturally evaluate for suitability and the need for specific living conditions of the species. Genetic variability and fluctuations in the number of individuals in populations (population or life waves) provide material for the inclusion of mechanisms for the struggle for the existence and survival of the fittest.
"Creative" directions
The struggle for existence as a result of natural selection leads to the fact that the result of evolution is the emergence of new species from ancestral. And natural selection can go in three directions:
- Driving - occurs with changes in the environment, and then the result of evolution is a shift in the average values of the sign in the direction of its increase or decrease.
- Stabilization - this way the evolution of the species will go under unchanging environmental conditions. With this type of selection, the optimal norm is preserved, and all extreme manifestations of the trait are eliminated from the population.
- Population-tearing selection begins with abrupt environmental changes. Then the majority of the population with signs normally dies sharply, and the carriers of the extreme indicators of the sign are most adapted to the changing conditions.
Genetic or reproductive isolation
Whatever the evolutionary way, the main condition for the formation of new species is reproductive isolation - the impossibility of free crossing of individuals for panmictic species (reproducing sexually). It is worth saying that the achievement of reproductive isolation in nature goes in two ways: allopatric (reproductive isolation is achieved by geographic separation of populations) and sympatric (isolation occurs on the same range with the maternal species). In any case, as soon as the regime of the impossibility of free crossing is established between populations, we can say that the result of the evolution of the organic world is the formation of a new species, and this process is completed.
Examples of Successful Animal Fitness
As soon as changes in the trait appear in the genome, they are tested by natural selection. The most successful ones are fixed morphologically and become adaptive. There are many examples in nature. Successful morphological adaptations include protective and protective coloring, masking agents and passive protection. Protective color, such as white plumage in partridges in winter, makes animals invisible against the background of the surrounding environment. Those organisms that have in their arsenal chemical means of protection against enemies possess a warning coloring. For example, red-black coloration of poisonous frog frogs or yellow-black coloration of poisonous salamanders. Disguise as a defense against enemies can be truly passive (the shape of the stick’s body really resembles a wand) or imitative (for example, the belly of a glass-butterfly is very similar to the belly of wasps, but the birds don’t touch it).
The Relativity of Evolutionary Fitness
All evolutionary scientists agree with the statement that the nature of fitness is relative. There are no absolutely useful signs, as there are no absolutely useless ones. All devices are developed in specific environmental conditions and when changed can be useless or even harmful. Protection from one enemy can be useless when defending from another (most stinging birds do not eat sting wasps and hornets, but flytraps and bee-eaters feed mainly on them). Behavioral characteristics may turn out to be meaningless (for example, the maternal instinct that forces a starling to feed a cuckoo). In other conditions, a useful organ or skill becomes a burden (for example, flying fish jumps out of the water and escapes from water predators, but becomes albatross prey).
Summarizing
About 7.5 million species of animals, about 300 thousand species of plants and 600 species of mushrooms, add 36 thousand species of unicellular organisms - all this diversity is the main result of the evolution of life on planet Earth. And all of them are perfectly adapted to their living conditions. Over the 3.7 million years of the existence of life on the planet, living organisms have constantly evolved and adapted to environmental conditions, and this process continues today.