Only those species with favorable mutations have a distinct advantage over other organisms in terms of survival.
Those who are more adapted, survive the struggle for survival, while those who are less adapted or not adapted are eliminated.
The term “survival of the fittest” was coined to describe this concept.
Survival of the fittest means that only the organism that is fit or adapted according to the environment will be able to survive.
Example:
There are red and green colored bugs in a habitat.
They are preyed upon by the birds in the habitat.
But, the birds prefer the taste of red bugs instead of green bugs so, after a period of time, there will be more green bugs as compared to the red bugs.
The green bugs breed and produce more green bugs until there are no red bugs left.
The green bugs were the fittest for survival in the habitat over the red bugs.