By carmen3521
1 years ago

Discovered on the spot in Galapagos: observe for the first time directly how a species is transformed into a new one

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Researchers discovered a population of Galapagos finches in Ecuador, in the process of becoming a new species.
This is the first example of speciation that could be observed directly on the ground.
The scientists detected the progress of speciation by observing the entire population of finches inhabiting a small island of the Galapagos called Daphne Mayor for several years.
The assistants of Darwin who are in danger of disappearing in Galápagos
The research was published in the journal Science.
The group of finches species to which the population of the new species called "Big Bird" belongs collectively known as Darwin's finches, since these were the birds that helped the British naturalist to discover the process of evolution by natural selection.
Unexpected visitor
In 1981, researchers noticed the arrival on the island of a male of a non-native bird species: the large cactus finch (G. conirostris).
Rosemary and Peter Grant saw that this male mated with a female of a local species (medium ground finch or G. fortis), resulting in fertile chicks.
Ave. Photo: P.R. Grant.
Image caption
This is an example of G. conirostris, the species that came to Daphne Major Island and gave rise to hybridization. Photo: P.R. Grant.
Almost 40 years later, the offspring of this couple - about 30 individuals - remains under observation.
What is the rapid evolution and how it transformed in a surprising way some small South American reptiles (and other animals)
"It is an extreme case of something that we are beginning to notice in general over the years, and evolution, in general, can happen very quickly," Roger Butlin, an expert in speciation who was not involved in the study, told the BBC. .
How to define a species?
This new population of finches is sufficiently different in its form and in its habits to native birds to be considered a new species, and individuals from different populations do not cross.In the past, it was thought that two different species could not produce fertile offspring to be recognized each as a different species.

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But in recent years, it has been established that many birds and other animals that we consider as unique species can in fact cross each other and produce fertile offspring.
"We no longer debate what is what defines a species because it is a futile discussion," says Butlin.
What is more interesting, he adds, is to understand the role that hybridization can have in the process of creating a new species. That is why this observation of the Galápagos finches is so important.
Stressful trip
Researchers believe that the original male may have flown about 100 kilometers from the habitat of the large cactus finch on Española Island.
This is a very large distance for a small finch, so it is very unlikely that he could have returned.
By identifying one of the ways in which a nine species can emerge and following the evolution of the entire population, the researchers made this case an example of speciation that takes place in an observable time span.For this reason, researchers have called these animals "the population of the Great Bird".
To scientifically verify if this population was genetically distinct from the native finch of the island, Peter and Rosemary Grant collaborated with the scientist Leif Andersson of the University of Upsala, in Sweden, who analyzed the population genetically for this study.
"One would have expected that the hybrid would begin to reproduce with one of the other species on the island until eventually disappearing ... but to our surprise we have confirmed that they are a closed reproductive group," Andersson told the BBC.
Due to their inability to recognize the songs of the new males, the native females do not mate with this new species.
And, in this study, the new genetic evidence revealed that only after two generations, complete reproductive isolation of the native species occurred.
Hybridization
For years, the individuals of the new species have reproduced exclusively among them.
"What we are saying is that this group of birds behaves like a different species, if a taxonomist came to this island and knew nothing of its history, I would say that there are four species here," explains Anderson.There is no evidence that they will reproduce again with an individual of the native medium finch species.
But even if they do, they now have a larger size and can exploit new opportunities.
It is likely that these traits are maintained by natural selection.
Thus, hybridization can lead to speciation, simply by adding an individual to a population. This can be a way for the new traits to evolve quickly.
"If you wait for mutations to change from one trait to another, it is a more difficult way to create a new species, but hybridization can be more effective than mutation," concludes Butlin.
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