During the struggle for
existence, organism which posses useful character can better adapt in the
environment , overcome others and survive whereas others eliminate from nature.
Organism which survive are called the fittest. So it is called as the survival
of the fittest named by herbert spencer.
Nature
is the superpower. It can select organism which can survive and reject which
cannot survive. This selection is done by nature so called as natural selection
named by darwin.
Eg for this is :
In Britain there were
two colored paper moth i.e dark coloured peppered moth (melanic) (scientific name :
Biston carbouria) and light coloured peppered moth (non-melanic) (scientific name :
Biston betularia). They used to live in branches of trees. Before the
industrial revolution in Britain, light colored peppered moth could match their
color with the branches of trees and remained safe from predator but dark
colored peppered moth were easily attacked by the predators.
After the industrial
revolution in Britain, the branches of trees blackened. Due to this the light
coloured peppered moth were easily attacked by predators and whereas the black coloured peppered moth were hidden protected from predators since they match their body with
branches of the trees. In 1845 A.D they occupied 1% of the total population of
Manchester city but in 1895 A.D their percentage increased to 9% in the
industrial area of Manchester city.
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