CBSE Class 10 Answered
Evolution is the sequence of gradual changes which take place in theprimitive organisms over millions of years in which new species are produced.
There are several theories proposed to explain the pattern of evolution,out of which Darwins theory of natural selection is most accepted.
The major events are:
1.Within any population,there is natural variation.Some individuals have more favourable variations than others.
2.Even though all species produce large number of offsprings populations remain fairly constant
3.This is due to struggle between members of same and different species for mate,food and space.
4.The struggle for survival between populations eliminates unfit individuals.the fit individuals wit favourable variations are nturally selected.
5.Individuals with favourable variations pass on these variations to their progeny.
6.These variations when accumulated over a long period of time lead to origin of new species.