Write a short note on Atavism.

Explanation

(i) Atavism is a modification of a biological structure whereby an ancestral trait reappears after having been lost through evolutionary changes in the previous generations.
(ii) Evolutionary traits that have disappeared phenotypically do not necessarily disappear from an organism's DNA.
The gene sequence often remains, but is inactive.Such an unused gene may remain in the genome for many generations.
(iv) As long as the gene remains intact, afault in the genetic control suppressing the gene can lead to the reappearance of that character again.
(v) Reemergence of sexual reproduction in the flowering plant Hieracium pilosella is the best example for Atavism in plants.