The continuity of life on Earth provides the unique ability of living things to create and maintain the internal environment, the exchange of substances with the environment and transmit these qualities to their offspring by heredity.

   It is known that all biological systems, from individuals to the biosphere, characterized by constant adaptation to environmental conditions. This creates a dynamic equilibrium associated with a particular set of environmental factors. Just change one of these factors to balance changed. If the limit is exceeded approximation, the equilibrium is disturbed, resulting in the death of individuals or the destruction of the system.

   Describe different processes of adaptation laws. Law limiting factors (factors statutory minimum), German chemist open Eustace von Liebig in the XIX century, says that the reaction of living organisms depends on environmental factors, which is present in the environment in the least. This could be, for example, mineral Battery (phosphorus, nitrogen, potassium, magnesium), which is contained in the soil in small amounts and limits plant growth.

   In accordance with another law, "zakonon tolerance" Shelford, for the individual, populations, or any other more complex ecological system there exists a range of values, so-called "interval endurance", within which its possible development. Within this range stand out optimal values ​​under which any ecological characteristics (growth, reproduction, etc.) will be maximum. Beyond the optimum is less favorable area within which survival is still possible, but environmental performance tend to zero.

   Biological evolution - a complex phenomenon consisting of many processes, but lies at the heart of the mechanism of natural selection. In the simplest form of the theory of evolution claims that those individuals who leave more offspring than other, are genetically better represented in subsequent generations and, therefore, the latter will be particularly similar to those organisms that have successfully multiplied.

Strength of selection, and thus the direction and rate of evolution are limited degree and nature of variability within the population. Selection operates on phenotypes, ie the real morphological, physiological, biochemical and behavioral manifestation of the body. Fitness of phenotype determines the success of survival and reproduction. However, selection can act only if there is a way by which the phenotypic characteristics can be inherited, that is transmitted to offspring and continue in a number of generations. Without this phenotypic adaptation would have no meaning.

    The result of the driving forces of evolution is the relative fitness of species to environmental conditions. By the term "fitness" includes color, body shape, behavior, particularly physiological and biochemical processes, etc. One of the most striking examples of adaptation is protective coloration that makes animal similar to surrounding objects.

   Processes within the species, which cause the formation of intraspecific groups - populations, subspecies and further - to the emergence of new species, called microevolutionary. By creating the theory of natural selection, Darwin selection effect linked only with individuals. However, studies are in the XX century. Proved that fully understand the effect of selection is possible only by taking into account the processes that occur in groups of organisms.

   Combination of genotypes of all individuals within the population, is its gene pool. In both populations are individuals with both dominant and recessive with signs. The question is: why is not replaced by a recessive allele dominant? This pattern purely mathematically explained in 1908 independently by two researchers Hardy and Weinberg, the names of which was called a law.
   The boundaries between different ways of speciation conditional: at various stages of microevolution one way or the other changes they act together. Primary geographical isolation may subsequently join environmental action that will lead to improvements in devices, so the process of speciation is adaptive in nature. When a species becomes established genetic closed system, the process stops. Within the species continue to accumulate mutations, which in turn may provide a new direction of evolution. Each type is real, but is historically a temporary link in the chain of the evolution.
    Here is a video about adaptation.