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 males 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.
Heidi Hardman | EurekAlert!
Nerves control the body’s bacterial community
26.09.2017 | Christian-Albrechts-Universität zu Kiel
Ageless ears? Elderly barn owls do not become hard of hearing
26.09.2017 | Carl von Ossietzky-Universität Oldenburg
Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.
Graphene is up to the job
At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.
Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
26.09.2017 | Life Sciences
26.09.2017 | Physics and Astronomy
26.09.2017 | Information Technology