Darwin’s finches offer fresh insights

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A bird family that helped Charles Darwin devise his famed theory has offered new insight into island biodiversity thanks to a study from Edinburgh University.

Darwin’s finches, which the famous naturalist collected from the Galapagos Islands, have reached a plateau in terms of how many different species of the birds can exist at any given time, according to new research from Scotland’s top university.

In the first study of its kind, scientists examined DNA from birds on the islands, including finches, to understand how the number of species had changed over millions of years.

Zebra finches
Zebra finches

 

They were investigating a theory predicting that islands can support a limited number of species.

Scientists were surprised to find that the number of bird species in the Galapagos is rising overall.

However, Darwin’s finches were found to contradict this outcome by having a fixed number of species, with new species frequently coming into existence, but only as others die out.

Researchers from the Universities of Potsdam, Edinburgh, and Groningen say their work gives a new perspective on whether island species’ diversity is limited or not.

Most of the finch species in the study – which have differently shaped beaks according to the food available locally – are found only on the Galapagos archipelago.

Darwin hypothesised that each species’ beak had evolved to suit the food available, which was central to his theory 0f evolution.

The research involved reconstructing the timeline of bird species arriving and diverging into new species in the Galapagos.

Dr Ally Phillimore of the School of Biological Sciences said: “Darwin’s finches have long been famous as an example of how a group can rapidly adapt to fill empty niches, but now it appears that there are limits to this.”

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