Why does a male copulate without delivering semen? In a study that sheds new light on the evolution of sexual behaviour, researchers have utilised a novel technique to reveal that in feral chickens, the simple stimulus generated by male mounting reduces the sexual promiscuity of a hen, indicating that even copulations that do not result in semen transfer, a puzzling male behaviour frequently observed in the chicken and many other species, may be crucial to defend the paternity of a male.
Females of many species often copulate with multiple males, leading to the competition between the ejaculates of different males over fertilisation (sperm competition). Males are therefore selected to avoid sperm competition by preventing females from mating with other males. In a number of species, mostly insects, female promiscuity is temporarily reduced following copulation and this has been associated with highly specialised male insemination products. However, these paternity defence mechanisms typically require costly male investment in a female, and are at odds with the fact that males often copulate without delivering semen. Importantly, previous studies have not considered that female promiscuity may be inhibited by stimuli generated by the simple act of male mounting.
In a new study, a team of researchers from Stockholm University (Sweden), University of Sheffield and University of Oxford (UK) tested this idea in the sexually promiscuous chicken, using a novel technique that separates the effect of insemination products from that of mounting alone. The researchers detected the response of hens to the mounting of a rooster, by fitting some hens with a light plastic harness covering their cloaca, thus preventing insemination. 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. Therefore, roosters can defend their paternity by reducing the promiscuity of the hens that they have inseminated, by exploiting the hen’s response to the simple stimulus of mounting. Consistent with this idea, roosters often mount hens that they previously inseminated without delivering additional semen. Therefore, this study demonstrates that even though the ultimate function of sex is fertilisation, copulations resulting in the delivery of little or no sperm are not necessarily functionally meaningless but may have an important evolutionary significance.
Hanne Lovlie | alfa
Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
UMD, NOAA collaboration demonstrates suitability of in-orbit datasets for weather satellite calibration
"Traffic and weather, together on the hour!" blasts your local radio station, while your smartphone knows the weather halfway across the world. A network of...
Fiber-reinforced plastics (FRP) are frequently used in the aeronautic and automobile industry. However, the repair of workpieces made of these composite materials is often less profitable than exchanging the part. In order to increase the lifetime of FRP parts and to make them more eco-efficient, the Laser Zentrum Hannover e.V. (LZH) and the Apodius GmbH want to combine a new measuring device for fiber layer orientation with an innovative laser-based repair process.
Defects in FRP pieces may be production or operation-related. Whether or not repair is cost-effective depends on the geometry of the defective area, the tools...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
16.01.2017 | Power and Electrical Engineering
16.01.2017 | Information Technology
16.01.2017 | Power and Electrical Engineering