A new study published in the journal Evolution suggests the beaks of birds did not adapt to the food types they feed on as previously thought.
The observation that Galapagos finch species possessed different beak shapes to obtain different foods was central to the theory of evolution by natural selection.
It has been assumed that this form-function relationship holds true across all bird species.
Connection Between Beak Shapes and Function
An international team of scientists from the United Kingdom, Spain and the U.S. used computational and mathematical techniques to better understand the connection between beak shapes and functions in living birds.
Researchers measured beak shape in a wide range of modern bird species from museum collections.
And looked at information about how the beak is used by different species to eat different foods.
This information helped the team assess the link between beak shape and feeding behavior.
“This is, to our knowledge, the first approach to test a long-standing principle in biology that the beak shape and function of birds is tightly linked to their feeding ecologies,” says Professor Emily Rayfield, from the University of Bristol’s School of Earth Sciences, and senior author of the study.
“The connection between beak shapes and feeding ecology in birds was much weaker and more complex than we expected,” says Guillermo Navalón, lead author of the study and a final year Ph.D. student at Bristol’s School of Earth Sciences.
“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,” adds Navalón.
He says that this is something that has been shown in other animal groups, but in birds, this relationship was always assumed to be stronger.
Birds Use Their Beaks for Everything
Co-author, Dr. Jesús Marugán-Lobón from Universidad Autónoma de Madrid says the results only made sense when you realize birds use the beak for literally everything.
“Therefore, it also makes sense they evolved a versatile tool not just for getting food, but also to accomplish many other tasks,” adds Dr. Marugán-Lobón.
The study is part of a larger research effort by the team in collaboration with researchers from other universities across Europe and the U.S. to better understand the main drivers of the evolution of the skull in birds.
Implications for Study of Fossil Birds
Dr. Jen Bright, a co-author from the University of South Florida, says they’ve seen similar results before in birds of prey.
But says this is the first time they studied the link between beak shape and ecology across all bird groups.
“We looked at a huge range of beak shapes and feeding ecologies including hummingbirds, eagles, parrots, puffins, flamingos, pretty much every beak you can think of,” adds Dr. Bright.
Navalón says 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,” says Navalón.
“We’re just starting to scratch the surface, and a lot more research is needed to fully understand the drivers behind beak shape evolution,” he adds.
Read the paper in the Evolution here.