CBSE - X - Biology - Heredity and Evolution
What are the various ways in which variation is caused? please explain in detail
Some of the causes of variation are:
(a) Mutation: Mutation refers to a sudden change in the nucleotide sequence of the genetic material of an organism. Change in a particular gene causes variation which results in change in phenotyope of the organism. Mutations can be caused various pollutants, radioactive substances, metals, etc.
(b) DNA replication: During DNA replication, changes in the genetic constitution occur while adding one more copy of DNA. It helps in causing variation which eventually leads to evolution and survival advantage.
(c) Environmental factors: Characteristics of organisms can be affected by factors such as climate, diet, culture and lifestyle. Variation caused by surroundings is called environmental variation.
(d) Sexual reproduction: Sexual reproduction involves the fusion of two different germ cells. It involves the process of meiosis or gamete formation. During meiosis, crossing over takes place between the genes and hence, new combinations are formed. Thus, greater variations and hence, greater diversities are generated.
(e) Gene flow: The movement of genes from one population to another causes genetic variation amongst the population.
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