A good example may be represented by different shapes and sizes of beaks in finches living on different Galapagos islands
Explanation:
According to the evolutionary theory proposed by Darwin, natural selection is a mechanism that acts on heritable phenotypic variation among individuals within a population. Genetic variation can be considered as the primary source of heritable phenotypic variation. Those organisms that are better adapted for a particular environment will have more chances to survive and reproduce, thereby passing these heritable traits to the next generation. For example, during his work, Darwin observed that the shape and size of beaks in finch species from different islands in the Galapagos archipelago varied as a consequence, i.e., as an adaptation, to the availability of food resources present in each island.
