What observations did Darwin make on the Galápagos Islands that helped convince him that evolution occurs? a. the existence of animals that did not fit into Linnaeus's classification system; b. the similarities and differences among cacti and tortoises on the different islands; c. the presence of species he had seen on other tropical islands far from the Galápagos; d. the radioactive age of the rocks of the islands; e. fossils of human ancestors

Video transcript

Hi everyone here we have a question asking what did Darwin observed among the finches that supports his theory of descent with modification a having the same diet and resources. If they all had the same diet and resources, they wouldn't have needed different beak shapes and sizes. So A is incorrect be occupying the same niche if they occupy the same niche, they also wouldn't have to have any modifications. See sharing the same genetic sequences. This is incorrect. D small differences and similarities in the finches, beaks, shapes and sizes. This is correct. Darwin observed that the finches on the Galapagos islands had different beak shapes and sizes depending on what they ate like. If a finch needed to get worms out of a tree, it would have a smaller beak to fit in the nooks and crannies of the tree. He also observed that these finches have a close resemblance to finch species in mainland of South America. So he then imagine that the species he found on the island might be a modified species from one of the original species on the mainland. So our answer here is d small differences and similarities in the finches, beak shapes and sizes. Thank you for watching. Bye.