Charles Darwin, an English naturalist and geologist, discovered several species of finches on the Galapagos Islands during his second voyage on the HMS Beagle in (1831). The Galapagos Islands are a small island archipelago consisting of thirteen main islands and six smaller islands. The vast majority of these finches varied from island to island. Darwin was fascinated by the wide variety of finches and how they differed from each other. For example, in the shape and size of their beaks from island to island. The main driver of diversification was due to ecological changes. Darwin did not consider Galapagos birds important; all Darwin discerned was that the finches' beaks were different from those of finches native to Ecuador. To this day, the Galapagos are still famous for their large number of endemic species. Darwin later hypothesized that Galapagos finches had evolved from a single ancestor species of finches, which had emerged from the mainland and then migrated to the islands. Darwin's finches underwent two evolutionary changes after a severe El Nino event caused a drastic change in the food supply of the Galapagos Islands. The finches, of varying beak shapes and sizes, had adapted to the food and resources available specifically on each island. When they settled on different islands, they each developed differently, depending on the island's ecosystem. Additionally, Galapagos Island finches played a central dual role in Darwin's original theory of biological evolution, through the idea of ​​natural selection due to environmental conditions and introgressive hybridization. The research carried out by Darwin and the species he brought back to England from his experiment...... middle of paper ......cies to shrink, that is to say they observed evolution by means of natural selection (Grant PR, et al. Science, 313. 224 - 226 (2006). Finches adapted to take advantage of food from the local environment in which they inhabited. Fine beaks and pointed where the birds' main food source was insects and larvae, and large claw-like beaks where their diet consisted of buds, fruits and larvae. The finch population developed in one way or another. on the other hand, beaks by natural selection were adapted to the location on which they were isolated. Hybridizations between Darwin's finches occurred repeatedly, although rarely, resulting in high morphological characteristics with the. (cactus finch) Geospiza Scandens and the (medium ground finch). ) Geospiza fortiz. Hybridization between variations had an introgressive effect on their genotypes but demonstrated higher relative fitness in various climatic contexts..