What did Darwin observe about animals on Galapagos?

Answer 1

Darwin's studies here were important because he could study a couple different island communities and see how/why they differ from their neighbors. These observation led to his theories on evolution. One of his most famous observations on the islands were of finches, sometimes called Darwin's finches. He noticed that the beak shape of the finches were different depending on the different habitats. The finches with the medium beak could be found where there were a large amount of seeds, and this size beak is the perfect size for seed eating. The finches that ate grubs had long skinny beaks that were perfect for digging out worms. Those that ates buds had the perfect bill shape for bud eating, those that ate leaves had the perfect bill shape for eating leaves, etc. This meant that although there were many finches on the islands, there was not much competition (fighting) over food because the finches were specialized.

Now this connects to Darwin's theories of evolution. Think about this possible scenario (a simplification of the Galapagos Islands): Imagine an island with worms, seeds, and leaves. Originally there was just one type of finch on an island, with a medium shape bill (that is good at eating seeds but can also eat leaves and worms). If every finch had a medium shape bill then every finch was just as good as the next at getting food. This means that there was a lot of competition and not every bird could get food (so not every bird could live and have babies). Overtime, through genetic variation/mutations, some birds were born with slightly longer bills and some with slightly shorter ones. Th birds with the longer bill were better at eating worms and this advantage helped them to survive and have babies (with longer bills). The finches with the shorter bill were experts at leaf eating and they survived and had children. The medium bill birds were still the best at seed eating so they survived and had children. Generations later this made three types of finches with three different beaks and three different foods that they are partial to. Since the three beak sizes ate different food, there was no longer competition, and every bird could eat. Overtime the birds may develop other advantages and become more different.

In short the Galapagos islands gave Darwin a view of how speciation works and what pressures encourage speciation.