galapagos islands

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 archipelago of islands which compose thirteen main islands and six smaller isles. The vast majority of these finches varied from island to island. Darwin was fascinated on the large variety of the finches and how they differed from one another. E.g., in their beak shape and size from island to island. The major driving force of diversification was due to ecological changes. Darwin did not think of the birds of the Galapagos as significant; all Darwin discerned was that the finches beaks were different compared to the finches native to Ecuador. To this day the Galapagos is still famed for their vast number of endemic species. Darwin later hypothesized that the finches of the Galapagos had evolved from a single ancestor species of finch, which had emerged from the mainland and later migrated to the islands. Darwin's finches underwent two evolutionary changes after a severe El Nino event which caused a drastic change in the food supply on the Galapagos Islands. The finches different shape and size of their beaks had adapted to the food and resources available specifically on each island. When they settled on different islands, they each developed differently, according to the ecosystem of the island. Moreover, the finches on the Galapagos Islands was twofold they played a pivotal movement on Darwin’s original theory of biological evolution, through the idea of natural selection due to environmental conditions and introgressive hybridization.

The research, Darwin performed and the species he had brought back to England from his expe...

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...cies to shrink, that is, they observed evolution by means of natural selection (Grant P. R., et al. Science, 313. 224 - 226 (2006). The finches adapted to take advantage of the food in the local environment they inhabited. Thin, and sharp beaks where the birds' main source of food was insects and grubs, and large claw-shaped beaks where their diet was buds, fruit and nuts. The finch population somehow developed beaks through natural selection that were suitable for that particular they were isolated on.

Hybridizations among Darwin’s finches occurred repeatedly though rarely, resulting in elevated morphological features with the (cactus finch) Geospiza Scandens and the (medium ground finch) Geospiza fortiz. Hybridization between the variations had an introgressive effect on their genotypes but demonstrated higher relative fitness under various climatic settings.