Explain how a sudden change in the environment either through a disaster or through shifts in conditions

A sudden change in the environment can cause something called Bottle-neck effect. Wherein it might affect the evolution of species in the area because it can reduce the size of the population at a rapid rate. This drop in population number can push be a 'bottle-neck' decrease of their size. In this case, certain alleles may be overrepresented among the survivors

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Explanation: