Darwin y las islas

Resumo

In his journey of circumnavigation aboard H.M.S. Beagle, Charles Darwin visited several islands. His extraordinary observations lay the foundations of evolutionary thought and influenced the subsequent development of his theories. The islands are also perceptively studied from a geological viewpoint, leading to the proposal of a general hypothesis, still extant, on the formation of coralline atolls. Likewise, Darwin developed some biogeographical hypotheses on the process of colonization of the islands from the evidence accumulated during his long journey. Perhaps the visit to the Galapagos Islands is, despite its brevity, the most important step of the trip. Specimens and data collected from tortoises and finches served years later as a solid basis for the explanation of adaptive radiation of a group of species from a common ancestor. Probably less well known is the crucial influence of observations on Galapagos’ mockingbirds (family Mimidae), from which Darwin outlined, within his famous ornithological notes and during the return journey, the first thoughts of his evolutionary theory. Since Darwin’s times, islands have played a key role in the genesis of the theory of evolution by natural selection. In fact, islands are today the best natural laboratory for the study of selective processes. The paradigmatic case is the remarkable research conducted in the Galapagos over several decades on Darwin’s finches by Peter and Rosemary Grant.