A new species of bird has arisen on the Galapagos Islands within just two generations of breeding, a new study has found.

In a case of history repeating itself, scientists made the discovery by observing Darwin's finches, named for their influence on the work of the evolutionary biologist.

Researchers discovered a 'newcomer' finch on the small island of Daphne Major 36 years ago, which bred with native birds to result in the new 'big bird' species.

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A new species of bird, the Galapagos 'big bird', has arisen on the pacific islands within just two generations of breeding. Scientists made the discovery by observing Darwin's finches, named for their influence on the work of the evolutionary biologist

NEW SPECIES IS BORN The Grants and their research team followed the new 'big bird' lineage on Daphne Island for six generations, taking blood samples for use in genetic analysis. The investigators discovered that the original male parent was a large cactus finch of the species Geospiza conirostris from Española island, which is around 62 miles (more than 100 km) to the southeast in the archipelago. The remarkable distance meant that the male finch was not able to return home to mate with a member of his own species and so chose a mate from among the three species already on Daphne Major. This reproductive isolation is considered a critical step in the development of a new species when two separate species interbreed. The offspring were also reproductively isolated because their song, which is used to attract mates, was unusual and failed to attract females from the resident species. The offspring also differed from the resident species in beak size and shape, which is a major cue for mate choice. As a result, the offspring mated with members of their own lineage, strengthening the development of the new species. Advertisement

Experts from Uppsala University in Sweden analysed DNA from the parent birds, collected over the years by biologists from Princeton University, as well as their offspring.

Over the last four decades, Barbara and Peter Grant have been carrying out field work on the islands.

In 1981, a graduate student working with the Grants on Daphne Major noticed a male that sang an unusual song and was much larger in body and beak size than the three resident species of birds on Daphne Major.

They found that the newcomer, belonging to one species, mated with a member of another resident on the island.

The researchers took a blood sample and released the bird, which later bred with a resident medium ground finch of the species Geospiz fortis, initiating a new lineage.

This gave rise to a new species, within just two generations, that today consists of roughly 30 individuals

Dr Barbara Grant, a senior research biologist at Princeton's department of ecology and evolutionary biology, said: 'The novelty of this study is that we can follow the emergence of new species in the wild.

'Through our work on Daphne Major, we were able to observe the pairing up of two birds from different species and then follow what happened to see how speciation occurred.'

While studying wildlife on the Galapagos Islands in the 19th century, Charles Darwin noticed finches found across different islands were fundamentally similar, but showed variations in their size, beaks and claws.

This led him to conclude that because of the distance between the islands, the finches must have evolved over time to the different environments they lived in and this ultimately inspired his 1858 theory of evolution by natural selection.

Darwin's finches only live in islands off the coast of mainland Ecuador.

The finches began as one species and started evolving into separate species an estimated three to five million years ago.

A member of the G conirostris species, this bird flew from around 62 miles (100 km) away to establish a new home on the Galapagos island of Daphne Major. There, the bird mated with a member of the G fortis species to give rise to the 'big bird' lineage

DARWIN'S FINCHES While studying wildlife on the Galapagos Islands in the 19th century, Charles Darwin noticed finches found across different islands were fundamentally similar, but showed variations in their size, beaks and claws. This led him to conclude that because of the distance between the islands, the finches must have evolved over time to the different environments they lived in and this ultimately inspired his 1858 theory of evolution by natural selection. Darwin's finches only live in islands off the coast of mainland Ecuador. The finches began as one species and started evolving into separate species an estimated three to five million years ago. Advertisement

The Grants and their research team followed the new 'big bird' lineage on Daphne Island for six generations, taking blood samples for use in genetic analysis.

The investigators discovered that the original male parent was a large cactus finch of the species Geospiza conirostris from Española island, which is around 62 miles (more than 100 km) to the southeast in the archipelago.

The remarkable distance meant that the male finch was not able to return home to mate with a member of his own species and so chose a mate from among the three species already on Daphne Major.

This reproductive isolation is considered a critical step in the development of a new species when two separate species interbreed.

The offspring were also reproductively isolated because their song, which is used to attract mates, was unusual and failed to attract females from the resident species.

The offspring also differed from the resident species in beak size and shape, which is a major cue for mate choice.

As a result, the offspring mated with members of their own lineage, strengthening the development of the new species

Researchers previously assumed that the formation of a new species takes a very long time.

Researchers previously assumed that the formation of a new species takes a very long time, but they observed it happening in just two generation. This image shows bird that is a member of the G fortis species, one of two species that interbred to give rise to the Big Bird lineage

The investigators discovered that the original male parent was a large cactus finch of the species Geospiza conirostris from Española island, which is around 62 miles (more than 100 km) to the southeastof Daphne Major in the Galapagos archipelago

NATURE'S LABORATORY: THE GALAPAGOS ISLANDS The Galapagos islands are situated 563 miles (900 km) west of mainland Ecuador, of which they are a part. They are some of the most remote land masses in the world. There are 21 islands but only four of them are inhabited, with a population of around 25,000. They contain more than 1,300 species found nowhere else on earth. With the islands at the intersection of three ocean currents, the sea is a mecca for marine life. The most famous species unique to the Galapagos include the giant tortoise, marine iguana, flightless cormorant and the Galapagos penguin - the only penguin species to be found in the Northern Hemisphere. Unesco decided to declare Galapagos a World Heritage Site In Danger in 2007 due to a boom in tourism. Annual visitor numbers have increased from 12,000 in 1979 to more than 300,000 today. Dozens of Galapagos species are now 'critically endangered'. Advertisement

But in the 'big bird' lineage it happened in just two generations, according to observations made by the Grants in the field in combination with the genetic studies.

The definition of a species has traditionally included the inability to produce fully fertile progeny from interbreeding species, as is the case for the horse and the donkey, for example.

However, in recent years it has become clear that some closely related species, which normally avoid breeding with each other, do indeed produce offspring that can pass genes to subsequent generations.

The authors of the study have previously reported that there has been a considerable amount of gene flow among species of Darwin's finches over the last several thousand years.

The full findings of the study were published in the journal Science.