Answers

2016-02-19T21:32:55+05:30
Overproduction of offsprings by organisms will lead to limited resources which will further lead to struggle for existance.during this time,some variations are found each species which may be favourable or unfavourable.the organisms with favourable variations survive and sustain the species whereas the organisms with unfavourable variations get eliminated.this is why it is said that variation is useful for the survival of species over long time but the variants have unequal chances of survival.
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