Innovation, Speciation: Darwin's finches theory doubted (Evolution)

by David Turell , Friday, January 25, 2019, 01:28 (1918 days ago) @ David Turell

As a result of examining all sorts of birds beaks, Darwin's theory about the finches as simply evolving their beaks to fit the food supply is not supported:

https://www.sciencedaily.com/releases/2019/01/190122115043.htm

"The observation that Galapagos finch species possessed different beak shapes to obtain different foods was central to the theory of evolution by natural selection, and it has been assumed that this form-function relationship holds true across all species of bird.

"However, a new study published in the journal Evolution suggests the beaks of birds are not as adapted to the food types they feed on as it is generally believed.

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"By measuring beak shape in a wide range of modern bird species from museum collections and looking at information about how the beak is used by different species to eat different foods, the team were able to assess the link between beak shape and feeding behaviour.

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"Guillermo Navalón, lead author of the study and a final year PhD student at Bristol's School of Earth Sciences, added: "The connection between beak shapes and feeding ecology in birds was much weaker and more complex than we expected and that while there is definitely a relationship there, many species with similarly shaped beaks forage in entirely different ways and on entirely different kinds of food.

"'This is something that has been shown in other animal groups, but in birds this relationship was always assumed to be stronger."

"Co-author, Dr Jesús Marugán-Lobón from Universidad Autónoma de Madrid, said: "These results only made sense when you realise birds use the beak for literally everything!

"'Therefore, also makes sense they evolved a versatile tool not just for getting food, but also to accomplish many other tasks."

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"'We looked at a huge range of beak shapes and feeding ecologies: hummingbirds, eagles, parrots, puffins, flamingos, pretty much every beak you can think of."

"Guillermo Navalón added: "These results have important implications for the study of fossil birds.

"'We have to be careful about inferring ecology in ancient birds, which we often assume based solely on the shape of the beak."

Comment: The finches are losing their prime importance in Darwin's theories. On the other hand it is clear the finch beaks do fit the type of seed they are encountering.