Fixture (in biology) - property of a living organism, acquired in the course of evolution, and the acquisition of this property.
The fitness of animals and plants to the conditions of existence from ancient times attracted the attention of the people. Representatives idealistic directions considered the fitness of organisms as a manifestation of the original feasibility inherent in all living things. Materialistic explanation observed in nature organic expediency for the first time gave Including Darwin's theory of natural selection, without which it is impossible to imagine the development process of adaptation.
Theory Including Darwin explained the origin of devices not only in organs such as teeth, legs, and others, but also painting, mimicry, safety devices and useful for the organism reactions. Arising in the process of natural mutagenesis (see Mutation) changes occur in different directions: useful, indifferent, or harmful to the body. Contributing to survive in the struggle for existence organisms - carriers of useful changes, natural selection fixes them.
From this point of view is easy to explain the development of, for example, these adaptations to the environment, as cryptic coloration, employee remedy some animals from others and disguise predators. This includes the white color of the animals of the Arctic countries, the yellow inhabitants of the desert, transparency of many aquatic organisms, etc. Painful complicated case - mimicry, i.e. imitation of color and shape of the body of some other animals and plants or things inorganic nature. A typical example of imitative similarities - similarity harmless edible animals with toxic inedible, usually brightly colored. Conspicuous colour in this case is called the warning. Many biological safety devices are used for defense. These are the shells of single-celled and shellfish, tortoise-shell, needles, tires, and poisonous and scent glands. To the devices of the same kind are the horns of hoofed mammals. The devices are also defensive reaction (reflexes), diverse, complexity and value representing the stereotypical responses of the organism to the devastating irritation. The fixture is not considered an integral properties of living beings, which started from the beginning of life and characterizing its processes (for example, metabolism, reproduction, and others).
Cm. also Adaptation, Variability, Instinct.