why is genetic variation important

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why is genetic variation important

Genetics: The science of transmission of characters from one generation to the next is called genetics.

  • Gregor Johann Mendel (1822 – 1884) is known as Father of Genetics.
  • The term genetics (Gk. Genesis – descent) was coined by Bateson (1906) for the elucidation of the phenomenon of heredity and variation.
  • In genetics actually we study about principles and mechanism of heredity and variations. Resolve all Your Biology Doubts from Physics Wallah.

Variations: Variations are the differences found amongst individuals of the same species, race and family in morphological, cytological, physiological and behaviouristic traits. Variations are mainly of two types -

(i) Somatic variation

(ii) Germinal variations

  • Somatic variation: They affect only the somatic cells of the organisms. They are neither inherited nor transmitted to next generation.

Somatic variation occurs due to three reasons – 

a) Environmental factors

b) Use and disuse of organs

c) Conscious efforts

  • Environmental factors: They include temperature, light, nutrition, water supply, humidity, medium or habitat, wind, topography, enemies etc.
  • Use and disuse of organs: In higher animals and human beings, greater use of an organ leads to its better development as compared to other organs which are less used.
  • Conscious efforts: They include receiving of education, learning of an art, development of some habits, training of pets.
  • Germinal variation: They are produced in the germ cells of an organism and are inheritable. They may be already present in ancestors or may be formed suddenly. They are of two types

a) Continuous variations

b) Discontinuous variations

  1. Continuous variations: They are the most common of all. They are neither new nor acquired variations. They are already present in different organisms or races of a species. Continuous variations are produced by
  • Segregation of chromosome at the time of gamete or spore formation
  • Crossing over of chromosome during meiosis
  • Chance combination of chromosomes during fertilization
  • If plotted, the graph appears bell-shaped with maximum individuals having average traits and the number of individuals declining with increase in degree of fluctuation.

Continuous variations are of two types

i) Substantive Continuous

ii) Meristic Continuous

i) Substantive Continuous: They influence appearance like height, colour, yield of milk or eggs etc.

ii) Meristic Continuous: They influence the number of parts e.g. number of grains in an ear of wheat, number of tentacles in

Discontinuous Variation: They are sudden unpredictable variations.

  • They are also called mutations.
  • All discontinuous variations or mutations may not pass to the next generation because of their appearance in the body cells after the differentiation of germ cells.
  • Discontinuous variations can be natural or induced. Induction is carried out by radiations and chemicals. Discontinuous variations are of two types

Substantive Discontinuous: They influence the appearance like size, colour, presence or absence of parts. e.g. Hairless Cat, Short-legged Ancon Sheep, Hornless Cattle, Piebald patching in man.

Meristic Discontinuous: They influence the number of parts. e.g. Polydactyly and Syndactyly

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why is genetic variation important

why is genetic variation important

why is genetic variation important

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