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201630Apr07:47

Birds of prey con­strained in the beak evo­lu­tion race

Infor­ma­tion
pub­lished 30 April 2016 | mod­i­fied 30 April 2016
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birds of prey skullNew research reveals that eat­ing dif­fer­ent foods does not deter­mine how birds of prey’s beaks evolve.

A clas­sic exam­ple of evo­lu­tion by nat­ural selec­tion is the way the beaks of bird species evolved into char­ac­ter­is­tic shapes to eat the dif­fer­ent food in their habi­tat. How­ever, new research from the Uni­ver­si­ties of Bris­tol, Sheffield, Madrid and York, pub­lished online on 28 April in the jour­nal Pro­ceed­ings of the National Acad­emy of Sci­ences, found this does not apply to all species, and that rap­tors in par­tic­u­lar have not enjoyed this evo­lu­tion­ary flexibility.

Lead author of the study, Dr Jen Bright, of the Uni­ver­sity of Sheffield, said: “Our results show that in birds of prey such as eagles and fal­cons, the shapes of the skulls change in a pre­dictable way as species increase or decrease in size. The shape of the beak is linked to the shape of the skull, and these birds can’t change one with­out chang­ing the other.

We think that being able to break this con­straint — let­ting the beak evolve inde­pen­dently from the brain­case, may have been a key fac­tor in enabling the rapid and explo­sive evo­lu­tion of the thou­sands of species of song­birds such as Darwin’s finches and Hawai­ian honeycreepers”.

The researchers used a method that allowed them to sta­tis­ti­cally quan­tify vari­a­tion in the shape of preda­tory bird skulls and see how this shape vari­a­tion com­pared with size, what the birds ate and how they are related to each other.

Our results are impor­tant because they may help us iden­tify one of the dri­ving fac­tors behind the out­stand­ing diver­sity of bird species we see in the mod­ern world
Samuel N. Cobb, co-​author, Depart­ment of Archae­ol­ogy and Hull York Med­ical School, Uni­ver­sity of York, UK »

Our research does not cast doubt on Darwin’s ideas, far from it,” said project lead Pro­fes­sor Emily Ray­field, of the Uni­ver­sity of Bris­tol. “Instead it demon­strates how evo­lu­tion has con­strained rap­tor skulls to a par­tic­u­lar range of shapes.”

“Basi­cally, if you’re a bird of prey and you’re small, you look like a tiny fal­con, and if you’re a bird of prey and you’re large, your skull looks like a vul­ture,” said co-​author Jesus Marugán-​Lobón, of the Autonomous Uni­ver­sity of Madrid.

The research team is now keen to extend and test their ideas in other groups of birds.


(Source: Uni­ver­sity of Bris­tol press release, 29.04.2016)


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