For the answer to the question above, the genetic evidence of phylogenetic relationships proves that organisms that are different now shared common ancestors.
The fossil record shows how organisms have evolved.
You could use the example of how humans have significantly changed the form of many animals by selective breeding.
There is evidence of adaptive radiation like the tortoises or finches of Galapagos. It also exists in the similarity of many species like all the different species of cats, horses, dogs
