Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Meaningless sex? Male mounting reduces sexual promiscuity of females

12.07.2005


Fakery is seen throughout the animal kingdom and is especially evident in the realm of mate selection and mating behavior. A puzzling behavior frequently observed in many species is copulation between males and females without the delivery of semen. In a world where reproduction is key to a species, survival, such behavior poses a real mystery. In a study that sheds new light on the evolution of sexual behavior, researchers have utilized a novel technique to reveal that in feral chickens, the simple stimulus generated by male mounting--in the absence of actual insemination--reduces the sexual promiscuity of a hen, indicating that even copulations that do not result in semen transfer may be crucial to defend the paternity of a male.




Females of many species often copulate with multiple males, leading to the phenomenon of sperm competition--the competition between the ejaculates of different males to successfully fertilize eggs. The battles of sperm competition occur at the cellular and molecular levels and involve the production of sperm-associated substances that boost the competitiveness of a male’s sperm; however, the production of these substances comes at an energetic cost to males. Males who can avoid such costs--and still successfully mate--may be at a reproductive advantage. Therefore, in some species, males may avoid sperm competition by preventing females from mating with other males. However, previous studies have not fully considered the possibility that female promiscuity may be inhibited by stimuli generated by the simple act of male mounting.

In the new study, a team of researchers led by Dr. Tommaso Pizzari of the University of Oxford tested this idea in the feral chicken, a sexually promiscuous species. By using a novel but technologically simple technique--fitting some hens with a light plastic harness covering their cloaca and thus preventing insemination--the researchers were able to separate the effect of insemination products from that of mounting alone and to detect the behavioral response of hens. The use of this technique demonstrated that mounting alone (independently of insemination) not only drastically inhibits the propensity of a hen to mate with a new rooster but also reduces the number of sperm that she obtains from a new rooster in the 2–4 days following mounting.


The researchers therefore showed that roosters can defend their paternity by reducing the promiscuity of the hens that they have inseminated; they do so by exploiting in these hens the response to the simple stimulus of mounting. Consistent with this idea, roosters often mount hens that they previously inseminated, but without subsequently delivering additional semen.

The study demonstrates that even though the ultimate function of sex is fertilization, copulations resulting in the delivery of little or no sperm are not necessarily functionally meaningless but may instead have an important evolutionary significance.

Heidi Hardman | EurekAlert!
Further information:
http://www.cell.com

More articles from Life Sciences:

nachricht Scientists coax proteins to form synthetic structures with method that mimics nature
15.01.2019 | University of Texas at Austin

nachricht DNA library of apoid wasps published
15.01.2019 | Staatliche Naturwissenschaftliche Sammlungen Bayerns

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Nanocellulose for novel implants: Ears from the 3D-printer

Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.

It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:

Im Focus: Elucidating the Atomic Mechanism of Superlubricity

The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.

One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...

Im Focus: Mission completed – EU partners successfully test new technologies for space robots in Morocco

Just in time for Christmas, a Mars-analogue mission in Morocco, coordinated by the Robotics Innovation Center of the German Research Center for Artificial Intelligence (DFKI) as part of the SRC project FACILITATORS, has been successfully completed. SRC, the Strategic Research Cluster on Space Robotics Technologies, is a program of the European Union to support research and development in space technologies. From mid-November to mid-December 2018, a team of more than 30 scientists from 11 countries tested technologies for future exploration of Mars and Moon in the desert of the Maghreb state.

Close to the border with Algeria, the Erfoud region in Morocco – known to tourists for its impressive sand dunes – offered ideal conditions for the four-week...

Im Focus: Programming light on a chip

Research opens doors in photonic quantum information processing, optical signal processing and microwave photonics

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a new integrated photonics platform that can...

Im Focus: Physicists uncover new competing state of matter in superconducting material

A team of experimentalists at the U.S. Department of Energy's Ames Laboratory and theoreticians at University of Alabama Birmingham discovered a remarkably long-lived new state of matter in an iron pnictide superconductor, which reveals a laser-induced formation of collective behaviors that compete with superconductivity.

"Superconductivity is a strange state of matter, in which the pairing of electrons makes them move faster," said Jigang Wang, Ames Laboratory physicist and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

11th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Aachen, 3-4 April 2019

14.01.2019 | Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

 
Latest News

Scientists coax proteins to form synthetic structures with method that mimics nature

15.01.2019 | Life Sciences

Next generation photonic memory devices are light-written, ultrafast and energy efficient

15.01.2019 | Information Technology

Viennese scientists develop promising new type of polymers

15.01.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>