Evolution in real time

The evolution of a new finch species on the Galapagos islands has been observed

Art by Amanda Cliffe

The Theory of Evolution via natural selection was first postulated by Charles Darwin in his book ‘On the Origin of Species’ nearly 160 years ago. If you know anything about Charles Darwin apart from this theory, you’ll probably know he sailed around South America on the exploratory voyage of the Beagle. You may also know that when he returned, he brought with him some specimens of the Galapagos finches – now one of the most famous examples of adaptive radiation.

 

Adaptive radiation is an evolutionary trend which occurs over many thousands of years, during which a colonizing species spreads out across an archipelago or differentiated environment and evolves into many more species – specifically adapted to the new habitats encountered. Adaptive radiation through natural selection has formed many related but morphologically different species of Finches.  Although the Finches are dull to look at (in 1793 Captain Colnett said of them “they are not remarkable for their novelty or beauty”) Darwin was struck by their differing beak forms. As he wrote, “seeing this gradation of structure in one small intimately related group, one might really fancy that from an original paucity of birds, one species had been taken and modified for different end”-  observing these species was essential to Darwin’s conceptualisation of evolution.

 

Now in 2017, there is real time, recorded, and proven example of Finch evolution. Evolution in microbes, yeast, and other organisms with short generation times has been recorded for years, but speciation events among vertebrates are relatively undocumented. There are two scientists in particular to credit for this discovery; Peter and Rosemary Grant. They are a husband and wife team who have spent six months of every year since 1973 capturing, tagging, and taking blood samples from finches on the island. They focused their study on Daphne Major, a small, ecologically simplistic island. During their studies, a Large Cactus Finch flew onto the island and successfully mated with a normal inhabitant – a Medium Ground Finch. Quite surprisingly, this mating produced fertile offspring.After many generations, they are now breeding successfully alongside the original species of finches. This random event has led to a distinct new species which has been named Big Bird.

 

So how did the speciation of Big Bird actually come about? It started with a mixed marriage – that is that the interloper (a Large Cactus Finch) abnormally bred with a female from another species. This may have occurred because he was so far from his own island that he was unable to return. In other words, he was a bit desperate. Importantly the offspring from this match were fertile, but due to combination of gene variance from the parent generation the offspring had a beak morphology that was unique – and a song which isolated them from reproducing with other birds on the island. The speciation incredibly only took two generations to occur. Even though Big Bird has only been around for a few years it is actually behaving like any of the other well-established Finch species. This truly is evolution in action; we had a chance event – the finch mixed marriage, followed by natural selection – and the survival of the new finche against natural barriers. Big Bird has survived because it was able to occupy a free niche in the environment, reducing competition with other finches. It also survived a severe drought. The most recent population figures show there are eight breeding pairs alive.

 

While observing Big Bird evolve is certainly a phenomenon for science, this kind of event is definitely not rare in nature. The events which caused the speciation of Big Bird are likely the very same which led to the present day situation of 15 different unique Finch species living on the Galapagos archipelago. Watch this space, as there could very easily be a Big Bird 2.

  • aedgeworth

    What we have is one type of finch being able to mate with a different type of finch and producing a new kind of finch species. I don’t quite understand why speciation is considered an example of mutation and natural selection, or even survival of the fittest. There is no evidence they had a survival advantage over any other species of finch. For that matter, all 14 different kinds of Darwin’s finches seemed to be surviving equally well.

    What we don’t know is how many kinds of finches were originally on the Galapagos Islands, or how they came to be there in the first place. That would truly represent “Origin of Species,” at least as far as those finches were concerned.

    No matter how many different species of finch can be produced through cross-breeding; that still is not evidence of a finch producing a non-finch, which evolution would require. Is there any evidence two finches have ever produced anything but a finch?

    It is often indicated that Charles Darwin observed those 14 different kinds of finches on the Galapagos Islands, and that inspired him to formulate his theory of evolution. What we are usually not told is that he was taught evolution theory by his grandfather, Erasmus Darwin, before Charles left on his famous voyage. He also had a copy of the first volume of Charles Lyell’s Principles of Geology. Lyell sent him the other two volumes while he was on his voyage. When Darwin observed those 14 kinds of finches he was viewing them through already established evolutionary eyes. He never gave his grandfather any credit, or Lyell, as far as I know. It would seem, not many others do either. Why would 14 species of finch cause anyone to conclude all life forms must have had a common ancestor? He had help.

    Finches produce finches, cats produce cats, dogs produce dogs, etc. etc. etc. Is there any evidence of one kind of animal producing a “non” anything, as evolution would require?

    Don’t give me the nonsense about evolution takes too long to observe. It supposedly has been going on for 600 million years. That is how you scientifically test evolution theory. If macroevolution has been going on for that long, we should be able to observe millions of life forms in all different stages of transitional change from one life form to another distinctly different life form. That is what would be predicted. All we can observe is life forms basically the way they always have been in recent history. Absolutely no transitional forms can be observed. None can be observed in the fossil record either. There should be millions. There are none.

    As humans we can have our DNA evaluated and find out how many different species of humans we came from. Our ancestry. I understand I have English, Irish, and American Indian ancestry. But what separated the different groups? Why were there English, Irish, French, Norwegian, etc. groups to begin with? They are all distinctively different groups. What was the “Origin” of these different human species?

    If an Englishman marries an Irish woman and produces a new species of human, why isn’t that considered evidence of evolution? What makes that different than the finches? If the new finches chose not to mate with the other two existing species of finch, that was a choice for whatever reason. There is no evidence they would be unable to.

    Speciation does represent change. Just not the type of change required by evolution theory. One type of finch can mate with another type of finch, and that somehow is proof my great, great, great (throw in a few more greats) grandfather was a bacterium? I’m sorry, I guess I just don’t have enough imagination for that. Two things evolution requires: a lot of imagination, and a great amount of faith in a basically unobserved process.

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Harriet Bruce
Isabelle Griffin
Maha Sultan
Megan Luddy
Lucie Rondeau Du Noyer
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Constance Millar
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Chloe Aitken

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