Question

Give the salient features of the Mutation theory.

Answer 1

Hint: Mutation takes place when a DNA gene is damaged or altered in such a way that it changes the genetic message transmitted by that gene. There are mainly four types of Mutation; Germline mutation, Chromosomal alteration, Point mutation and Frameshift mutation. The agent of substance which brings about a permanent change to the physical composition of a DNA gene is called Mutagen

Complete answer:
The salient features of Mutation Theory are:
i) Mutations are irregular and form the raw material of evolution.
ii) Mutations are massive alterations occurring spontaneously in the biological population. Such changes are heritable, generating new species.
iii) Mutations appear suddenly and become operational immediately. They also give rise to new species at one step.
iv) Mutations occur full-fledged. There are no intermediate stages between the generation of new species and the pre-existing ones.
v) Mutations could be advanced and constructive or retrogressive and destructive.
vi) Mutations can occur in any direction and are subjected to natural selection. Natural selection eliminates harmful mutants.
vii) The main advantage of the mutation theory is that it explains evolutionary changes within a short period and explains variations that are slow and continuous.
viii) The disadvantage of the mutation theory is that it failed to explain the development of mimicry, mutual depen­dence of flowers and pollinating insects.

Note: The mutation theory was given by Hugo de Vries in 1901. Cancer is the most common genetic disease which is caused by a mutation in the growth control genes. Sickle cell anaemia is caused by a mutation that causes the red blood cells to become abnormal. But, having this mutation protects the people of Africa from Malaria.