how does acumulated variations affect the evolution of the organisms ? how it promotes the survival of organisms?
Variation in the nature arises from sexual reproduction. Asexual reproduction does not contribute towards the variation as the offspring are identical to parent.The variation which makes organism better adapted for the given environment accumulates in the population. Environment promotes organisms which are best suited (adapted) to it. This is called survival of the fittest. So, only useful variations accumulate in the environment where as non useful don't. The accumulation of the variation leads to formation of the new species thus effect evolution. When there are sudden changes in the environment then the species which can't cope with change dies and others having adaptation ( because of variation) survives. Thus, accumulation of variation affects evolution.