What is the role of the genotype and environmental conditions in the formation of the phenotype? Give examples.

Some signs are formed only under the influence of the genotype and their manifestation does not depend on the environmental conditions in which the organism develops. For example, in a person who has genes IA and IB in the genotype, an IV blood group is formed regardless of living conditions. At the same time, growth, body weight, the number of red blood cells in the blood and many other signs depend not only on the genotype, but also on environmental conditions. Therefore, organisms having the same genotypes (for example, monozygotic twins) can differ from each other in phenotype.
In 1895, the French botanist G. Bonnier conducted the following experiment: he divided the young dandelion plant into two parts and began to grow them in different conditions – on the plain and high in the mountains. The first plant reached normal height, and the second turned out to be dwarf. This experience shows that the formation of the phenotype (i.e., traits) is influenced not only by the genotype, but also by environmental conditions.
Another example illustrating the influence of the external environment on the manifestation of characters is the change in coat color in Himalayan rabbits. Usually at 20 ° C their fur is white on their whole body, with the exception of black ears, paws, tail and muzzle. At 30 ° C, rabbits grow completely white. If a Himalayan rabbit shaves its hair on its side or back and keeps it at an air temperature below 2 ° C, then instead of white wool, black will grow.

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