Posleduyuschie period

The actual material received in posleduyuschie period, allowed us to widen and deepen the theoretical foundations of evolutionary theory. Works in the field of paleontology (C. O. Kovalevsky), based on historical method, allowed to fill a number of gaps in the evolutionary doctrine. An important step in the further development of evolutionary theory served as research A. O. Kovalevsky and I. I. Mechnikov in the field of evolutionary embryology.
A great role in the development of evolutionary theory played a founder of evolutionary morphology A. N. Severtsev (1866 - 1936), which on the basis of their comparative-morphological studies revealed the ways and mechanisms of phylogenetic development of animal organs in connection with their duties and the environment. Severtsev revealed two main directions of evolution of the authorities. One of them is a progressive change of the body, increasing the organism vital activity and enabling access to the new environment. For example, changing the structure of the fins of the ancient lobe-finned fish has led to the possibility of their landfall, the formation of the limbs ground type and, ultimately, the formation of terrestrial vertebrates. Another direction of evolution is associated with adaptations to the specific, more specialized and individual conditions of existence, such as the formation of the structural features of the mole to exist only under the ground.
The Doctrine A. N. Severtsev about the evolution of the bodies was developed further And. And. the Proposed with the positions of rational formation of an integral organism, connected by a chain of dependencies as with the history of development of this type of organisms ( phylogeny)and individual development (ontogenesis), in interaction with the external environment.
The modern doctrine of evolution is based on a solid Foundation of the provisions of genetics to disclose material nature of heredity. Evolutionary unit is not an individual and not look, and the population is the aggregate of individuals of one species, long-living in a certain territory and freely crossed among themselves.
In the basis of genetic changes in populations lies mutational variability as a result of unexpected mutations - genetic changes of the genetic apparatus. Mutations can occur in any cage at any stage of development both in normal conditions of existence (spontaneous mutations), and under the influence of any physical or chemical factors (induced mutations).
Therefore, the driving factors are mutagenesis (education mutations and natural selection. The process of natural selection is the survival of the organisms, mutational changes which provide the greatest adaptation of organisms to their environment. In clarifying the role of mutations in the evolutionary process played a large role in the works of C. S. Chetverikov, M. I. Vavilov, I. I. Schmalhausen.
All work related to the disclosure of the mechanism of evolution, aimed at the disclosure of genetic evolution of a population, which is the basis of differentiation of the form, and essence of processes of divergence divergence of populations, leading to the emergence of new species.
Phenomena in the evolution of natural populations associated with the consequences of human activities, such as, for example, changes in the chemical and radiation environment, can lead to quick (impulsive) the evolution of populations. Thus, genetic studies of populations of viruses, bacteria and other microorganisms under the action of antibiotics and sulfonamides has shown mutation nature rapid evolution of these forms in the direction of the emergence of resistant strains. The introduction of insecticides for mass pest control has led to the emergence of new forms of insects resistant to poisons, and the impact of radiation has led to the evolution of populations at radiostability etc.
One of the main places in the modern evolutionary doctrine is a genetic analysis of the human population. The originality of the population genetics of man is that natural selection has lost the role of a leading factor in the evolution of man. However, the value of genetics of the human population is extremely high, as it occupies a key place in the analysis of the spread of hereditary diseases (see), in assessing the effect of radiation and other physical and chemical influences on the heredity of human rights.
Further development of evolutionary theory is primarily due to the success of evolutionary genetics that studies the transformation of genetic systems in the process of historical development of organisms. The latest achievements of molecular biology (see) allows for a fresh look at the mechanism of evolution. Transcript of amino acid code, the discovery of the molecular mechanisms of the phenomenon of mutation, the problem of deployment of genetic information in the process of ontogenesis, the problem of studying the regularities of phylogeny prepared the ground for a new qualitative leap in the development of evolutionary theory and the whole of biology in General. Evolutionary doctrine remains the main weapon of biologists-materialists, constantly enriched with new factual and theoretical data, developed along with the deepening of knowledge of the nature of the organic world.
Cm. also, Biology, Genetics, Variation, Molecular biology, Genetics.