Question

What do you mean by variation ? How does it occur ? What advantages does it offer ?

Answer 1

variation means that the changes occur in our genes. 

it occur in genetic drift,natural seletion, geographical isolation and also

by evolution.

variation offer a advantage is that an organisms makes better him by other.

Answer 2

variation- differences in the same species according to the different climatic condition, geographical isolation etc. 
  it occurs because to survive. if variation occurs then the animals will be able to survive according to condition.
   its advantage is  the species never extinct.