Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

More flight than fancy? A new theory on the function of barn swallow tail streamers

05.04.2007
Scientists from the universities of Exeter and Cambridge have turned a textbook example of sexual selection on its head and shown that females may be more astute at choosing a mate than previously thought.

New research, funded by the Leverhulme Trust and published online on 5 April in Current Biology, shows that differences in the lengths of the long tail feathers possessed by male barn swallows are more about aerodynamics than being attractive. Female barn swallows favour mates with longer tails and the prominent male tail ‘streamers’ that extend beyond the tail were cited by Darwin as evidence of sexual selection. Now for the first time, scientists have tested this assumption and found that these ‘ornaments’ are in fact linked to natural selection. Females are selecting mates with longer, more aerodynamic tails, rather than on the basis of attractive, but meaningless ornaments.

By studying individuals with varying tail lengths, the research team established the ideal tail length for catching insects and performing manoeuvres and then determined how much the tail had been extended beyond this. They found that the optimal streamer length for flight varies between individuals but surprisingly there is no variety in the extension beyond this. The research showed the size of tail ornaments developed is determined by natural selection and not sexual selection as previously thought.

Professor Matthew Evans of the University of Exeter explains: ‘The part of the streamer thought to be ornamental, rather than functional, does not vary between individuals. This means that swallow tail streamers are not true ornaments. The streamer’s purpose may just be to signal the sex of the individual, rather than to communicate attractiveness to choosy females. We believe that overall tail length is performing the function of attracting females, but females are choosing between males on the sensible criteria of how good they are at flying and catching prey. The ornamental part of the tail is simply saying ‘I am male’.’

... more about:
»female »individual »sexual »streamer »swallow

Attributions developed through sexual selection can be impractical for other functions but traits developed through natural selection are beneficial to survival. Whereas scientists previously believed female barn swallows to be attracted to a male’s streamer, which had no function, this research suggests that their selection is perhaps based on the more useful information communicated by tail length, which signals their success in flight and hunting.

‘The results of this study force us to question long-term assumptions about the nature of ornamentation and sexual selection,’ concludes Professor Evans.

Sarah Hoyle | alfa
Further information:
http://www.exeter.ac.uk

Further reports about: female individual sexual streamer swallow

More articles from Life Sciences:

nachricht Meadows beat out shrubs when it comes to storing carbon
23.11.2017 | Norwegian University of Science and Technology

nachricht Migrating Cells: Folds in the cell membrane supply material for necessary blebs
23.11.2017 | Westfälische Wilhelms-Universität Münster

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Underwater acoustic localization of marine mammals and vehicles

23.11.2017 | Information Technology

Enhancing the quantum sensing capabilities of diamond

23.11.2017 | Physics and Astronomy

Meadows beat out shrubs when it comes to storing carbon

23.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>