The crew made it to South America in a few short months, after a brief stop in the Canary Islands. Darwin spent most of his time on land collecting data. They stayed for more than three years on the continent of South America before venturing on to other locations. Charles Darwin and the rest of the HMS Beagle crew spent only five weeks in the Galapagos Islands, but the research performed there and the species Darwin brought back to England were instrumental in the formation of a core part of the original theory of evolution and Darwin's ideas on natural selection which he published in his first book.
Darwin studied the geology of the region along with giant tortoises that were indigenous to the area. Perhaps the best known of Darwin's species he collected while on the Galapagos Islands were what are now called "Darwin's Finches". In reality, these birds are not really part of the finch family and are thought to probably actually be some sort of blackbird or mockingbird. However, Darwin was not very familiar with birds, so he killed and preserved the specimens to take back to England with him where he could collaborate with an ornithologist.
It was back in Europe when he enlisted in the help of John Gould, a celebrated ornithologist in England. Gould was surprised to see the differences in the beaks of the birds and identified the 14 different specimens as actual different species - 12 of which were brand new species. He had not seen these species anywhere else before and concluded they were unique to the Galapagos Islands. The other, similar, birds Darwin had brought back from the South American mainland were much more common but different than the new Galapagos species.
Charles Darwin did not come up with the Theory of Evolution on this voyage. The ecological niches exert the selection pressures that push the populations in various directions. On various islands, finch species have become adapted for different diets: seeds, insects, flowers, the blood of seabirds, and leaves.
The ancestral finch was a ground-dwelling, seed-eating finch. After the burst of speciation in the Galapagos, a total of 14 species would exist: three species of ground-dwelling seed-eaters; three others living on cactuses and eating seeds; one living in trees and eating seeds; and 7 species of tree-dwelling insect-eaters. Scientists long after Darwin spent years trying to understand the process that had created so many types of finches that differed mainly in the size and shape of their beaks.
Most recently, Peter and Rosemary Grant have spent many years in the Galapagos, seeing changing climatic conditions from year to year dramatically altering the food supply. Charles Darwin's observations, notes and collected organisms from the Galapagos Islands during his 5-year voyage on the Beagle resulted in his theory of evolution by natural selection, one of the best substantiated theories in the history of science.
He collected several finch species , including the warbler finch, sharp-beaked finch, ground finch, small tree finch, large tree finch, common cactus finch and large ground finch. But Darwin failed to note which islands each particular finch came from. We identified HMGA2 gene varies systematically between species with different beak sizes. The large beak HMGA2 variant was more common in birds that died during the episode of drought, while small beak variant was common in those birds that survived.
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