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

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Researchers invent tiny, light-powered wires to modulate brain's electrical signals

21.02.2018 | Life Sciences

The “Holy Grail” of peptide chemistry: Making peptide active agents available orally

21.02.2018 | Life Sciences

Atomic structure of ultrasound material not what anyone expected

21.02.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>