phenotypic variability - is a very important process that allows the body's ability to survive.It is thanks to her, he is able to adapt to environmental conditions.
first modification variability of organisms has been noticed in the studies of Charles Darwin.Scientists believe that just so happens natural selection in the wild.
Phenotypic variation and its main characteristics
It's no secret that during the evolution of living organisms are constantly changing, adapting to survive in the external environment.The emergence of new species was provided by several factors - changes in the structure of hereditary material (genotypic variability), as well as the emergence of new properties that make viable the body when changing environmental conditions.
phenotypic variability of a number of features:
- Firstly, in such a manner for the phenotype - a set of external characteristics and properties of a living organism.Genetic material does not change.For example, two populations of animals that live in different conditions, have some differences in appearance, despite an identical genotype.
- On the other hand, the phenotypic variability is a group character.Changes in the structure and properties arise in a given population of organisms.For comparison, it should be said that changes the genotype of single and spontaneous.
- Modification variability reversible.If you remove those specific factors which caused a reaction from the body, over time features will disappear.
- phenotypic changes are not inherited, as opposed to genetic modification.
phenotypic variability and reaction norm
As mentioned, changing the phenotype is not the result of any genetic modifications.This is primarily a reaction to the impact of genotype environmental factors.In this case, he does not change the set of genes, but the intensity of their symptoms.
Of course, these changes have their own limits, which are called normal reaction.The rate of reaction - a range of all possible variations of which are selected only those options that are appropriate for the habitat under certain conditions.This index depends exclusively on the genotype, and has its own upper and lower limits.
phenotypic variability and its classification
course typology of variability is very relative, since all the processes and stages of development of the body are still not fully understood.However, modifications are divided into groups, depending on certain characteristics.
If we take into account the changed signs of the body, they can be divided into:
- Morphological (changes the look of the body, such as the density and color of the hair).
- Physiological (there are changes in the metabolism and physiological characteristics of an organism, such as a human, climb mountains, dramatically increases the number of red blood cells).
by time isolated modification:
- Non-inherited - changes are present in only one or a population of individuals who have been directly affected by the external environment.
- Long versions - talk about them when acquired adaptation offspring transmitted and stored even for 1-3 generations.
There are also some forms of phenotypic variability, which do not always have the same value:
- modifications - a change that bring the body to use, adapt and provide normal functioning in the environment.
- Morphosis - those changes in the phenotype, which occur under the influence of aggressive, extreme environmental factors.There variability goes far beyond the norm of reaction and may even lead to death of the organism.