What made finch species in the island of Galapagos have different beak structures?

The finches in the above video were collected from the Galápagos Islands in 1835 by Charles Darwin and his colleagues during the second voyage of HMS Beagle (1831-1836).

The different finch species on the islands are closely related to each other, but show wide variations in beak and body size and feeding behaviour.

In particular, changes to the size and shape of the beaks have enabled the different species to specialise in different types of food: seeds, insects, cactus flowers and fruits or even bird blood. 

The Galápagos finches are a classic example of adaptive radiation. Their common ancestor arrived on the islands a few million years ago. Since then, a single species has evolved into different species that are adapted to fill different lifestyles.

Darwin didn't recognise the significance of these birds when he first encountered them as he didn't realise how closely related they were to each other. Later, he wrote: 'Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends.' (Journals of Researches, 2nd Edition, 1845)

Suggestions for use in class

The video above shows six different species of finch found by Darwin and his colleagues on the Galápagos Islands. Overall, there are about 15 closely related species of Darwin's finches.

The video could be used as starter on a lesson on evolution, adaptation and natural selection, or as a part of a discussion on the evidence gathered by Darwin for his theory of evolution.

The video asks: 'Can you spot the differences between these finches?'

The birds differ in plumage and body size but the most obvious differences between the birds are the size and shape of their beaks, which are dependent on their food preferences and specialisations. The thinnest beak belongs to the green warbler finch which uses it to probe for insects. The massive, stout beak of the large ground finch enables it to crush big hard seeds. The long pointed beak of the common cactus finch helps it extract seeds from cactus fruit.

Other questions you could raise with your class after they have seen the video:

• Why do you think the different species have different shaped beaks?
• Molecular evidence indicates that the single ancestor species of the finches arrived in the Galápagos Islands between 2-3 million years ago. Since that time, these volcanic islands have undergone many changes in sea level, elevation and climate. What selection pressures might the finches have faced?
• The HMS Beagle team collected thousands of specimens of plants and animals during their expedition. Why did they do this?

On the Galapagos Islands, Darwin observed several species of finches with unique beak shapes. ... 1: Darwin's Finches: Darwin observed that beak shape varies among finch species. He postulated that the beak of an ancestral specieshad adapted over time to equip the finches to acquire different food sources.

When Charles Darwin stepped ashore on the Galapagos Islands in September 1835, it was the start of five weeks that would change the world of science, although he did not know it at the time. Among other finds, he observed and collected the variety of small birds that inhabited the islands, but he did not realize their significance, and failed to keep good records of his specimens and where they were collected. It was not until he was back in London, puzzling over the birds, that the realization that they were all different, but closely related, species of finch led him toward formulating the principle of natural selection.
In his memoir, The Voyage of the Beagle, Darwin noted, almost as if in awe, "One might really fancy that, from an original paucity of birds in this archipelago, one species had been taken and modified for different ends."
Indeed, the Galapagos have been called a living laboratory where speciation can be seen at work. A few million years ago, one species of finch migrated to the rocky Galapagos from the mainland of Central or South America. From this one migrant species would come many -- at least 13 species of finch evolving from the single ancestor.
This process in which one species gives rise to multiple species that exploit different niches is called adaptive radiation. 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. As a result, certain of the finches have lived or died depending on which species' beak structure was best adapted for the most abundant food -- just as Darwin would have predicted.

How were the finches on Galapagos Islands different from one another?

What made finch species in the island of Galapagos have different beak structure Brainly?

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