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Evo­lu­tion


A Col­lec­tion of News by Moos


201723Oct19:59

Great tits may be adapt­ing their beaks to birdfeeders

Infor­ma­tion
pub­lished 23 Octo­ber 2017 | mod­i­fied 07 Decem­ber 2018
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A British enthu­si­asm for feed­ing birds may have caused UK great tits to have evolved longer beaks than their Euro­pean coun­ter­parts — accord­ing to a new study.

The find­ings, pub­lished on 20 Octo­ber in Sci­ence, iden­tify for the first time the genetic dif­fer­ences between UK and Dutch great tits which researchers were then able to link to longer beaks in UK birds.

Great tit by Lewis SpurgenGreat tit. Image credit: Lewis Spurgin/​UEA

Using genetic and his­tor­i­cal data, the research team also found that the dif­fer­ences in beak length had occurred within a rel­a­tively short time frame. This led them to spec­u­late that there may be a link with the rel­a­tively recent prac­tice of putting out food for gar­den birds.

The research is an inter­na­tional col­lab­o­ra­tion involv­ing researchers from the Uni­ver­si­ties of Sheffield, East Anglia, Oxford, Exeter, Wagenin­gen and the Nether­lands Insti­tute of Ecology.

The find­ings are part of a long term study being car­ried out on pop­u­la­tions of great tits in Wytham Woods, in the UK, and in Oost­er­hout and the Veluwe, in the Nether­lands. The team screened DNA from more than 3000 birds to search for genetic dif­fer­ences between the British and the Dutch pop­u­la­tions. These dif­fer­ences indi­cate where nat­ural selec­tion might be at work.

The spe­cific gene sequences which had evolved in the British birds were found to closely match human genes known to deter­mine face shape. There were also strong sim­i­lar­i­ties with genes iden­ti­fied with beak shape in Darwin’s study of finches – one of the best-​known exam­ples of how phys­i­cal traits have adapted to dif­fer­ent envi­ron­ments in the wild. This led the researchers to think that great tit beaks were evolv­ing by nat­ural selec­tion in British great tits, per­haps in response to the wide­spread use of bird feeders.

Researchers at Oxford Uni­ver­sity have been study­ing the Wytham Woods great tit pop­u­la­tion in Oxford­shire for 70 years and so the team had access to a wealth of his­tor­i­cal data which clearly showed that the British great tits’ beaks were get­ting longer over time. They were also able to access data from elec­tronic tags fit­ted to some of the Wytham Woods birds, which enabled them to track how much time was spent at auto­mated bird feeders.

Between the 1970s and the present day, beak length has got longer among the British birds. That’s a really short time period in which to see this sort of dif­fer­ence emerg­ing,” says Pro­fes­sor Jon Slate, of the Depart­ment of Ani­mal and Plant Sci­ences at the Uni­ver­sity of Sheffield. “We now know that this increase in beak length, and the dif­fer­ence in beak length between birds in Britain and main­land Europe, is down to genes that have evolved by nat­ural selection.”

The team also found that birds with genetic vari­ants for longer beaks were more fre­quent vis­i­tors to the feed­ers than those birds which did not have that genetic variation.

Dr Lewis Spur­gin, co-​first author, from the School of Bio­log­i­cal Sci­ences of the Uni­ver­sity of East Anglia, said: “In the UK we spend around twice as much on bird­seed and bird­feed­ers than main­land Europe – and, we’ve been doing this for some time. In fact, at the start of the 20th cen­tury, Punch mag­a­zine described bird feed­ing as a British national pas­time. Although we can’t say defin­i­tively that bird feed­ers are respon­si­ble, it seems rea­son­able to sug­gest that the longer beaks amongst British great tits may have evolved as a response to this sup­ple­men­tary feeding.”

The team car­ried out fur­ther inves­ti­ga­tions into the gene with the strongest asso­ci­a­tion with beak length and con­firmed that British birds with the longer-​beaked gene vari­ants were more suc­cess­ful at repro­duc­ing in the UK but not in the Nether­lands, giv­ing even more evi­dence that nat­ural selec­tion is at work in the UK population.

It’s cer­tainly true that birds who have adapted to bet­ter access food will be in bet­ter con­di­tion gen­er­ally, and so bet­ter able to repro­duce and out­per­form oth­ers with­out that adaptation.

Dr Lewis Spur­gin, School of Bio­log­i­cal Sci­ences, Uni­ver­sity of East Anglia

The researchers have already started to fol­low up the study by look­ing at DNA sam­ples from great tit pop­u­la­tions across Europe and their ini­tial evi­dence sug­gests that the longer beak genetic vari­ants are spe­cific to the UK.

Dr Mirte Bosse, of the Nether­lands Insti­tute of Ecol­ogy and Wagenin­gen Uni­ver­sity, and co-​first author of the paper, explains: “The way we’ve detected evo­lu­tion­ary dif­fer­ences in the wild is unique. It was the genome that led the way. That this is pos­si­ble for a trait influ­enced by so many genes, holds many promises for future discoveries.”

(Source: Uni­ver­sity of East Anglia press release, 19.10.2017)


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