Peppered moths. They were initially light coloured but the industrial revolution came and cover the trees with soot or dust, darkening the tree barks. The light coloured moths were preyed on easily so more dark coloured moths who were able to camouflage survived. The darker coloured moths has better reproductive success, passed on the favourable alleles to their young, over generations, increase the frequency of dark coloured allele in the gene pool.
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