For many species, the ratio of sons to daughters a mother produces can have a profound effect on her evolutionary success. Too many sons, or too many daughters, may mean a female does not pass on as many copies of her genes to the next generation as another mother. The crucial determinant of sex ratio for many species will be how likely related individuals will interact, in particular whether brothers will be competing amongst themselves to mate with their sisters. This situation becomes increasingly likely in species with very structured populations, where only one or a few females will produce offspring locally, and related males and females will be mating with each other. To reduce this local mate competition between sons, mothers should bias the sex ratio towards daughters, reducing male competition and providing them each with more females to mate with.
Parasitic wasps that lay their eggs on insect hosts often have such a population structure, and work has shown that sex ratios vary with the number of females contributing to a host or group of hosts, as expected. For example, in the parasitic wasp Nasonia vitripennis, females vary their offspring sex ratios in response to both the presence of other females on a patch, and the presence of eggs already laid on the host they are about to use themselves. However, often groups of hosts will be a mixture of parasitised and unparasitised hosts, and the mating environment will be influenced by wasps emerging from all the parasitised hosts, some related to each other but some not.
In a new study featured in the September issue of The American Naturalist, David M. Shuker (University of Edinburgh) and colleagues show that females alter the sex ratio they produce on a host by considering whether there are already eggs on the host they are using and if there are other eggs already laid on other hosts in the patch. The researchers developed a new theory to explain what the best sex ratios should be for different situations and to demonstrate that females qualitatively confirm these novel predictions. This suggests that females are incredibly subtle in their use of information from the whole patch when it comes to making their sex ratio decisions.
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08.12.2017 | DOE/Argonne National Laboratory
‘Spying’ on the hidden geometry of complex networks through machine intelligence
08.12.2017 | Technische Universität Dresden
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
An interdisciplinary group of researchers interfaced individual bacteria with a computer to build a hybrid bio-digital circuit - Study published in Nature Communications
Scientists at the Institute of Science and Technology Austria (IST Austria) have managed to control the behavior of individual bacteria by connecting them to a...
Physicists in the Laboratory for Attosecond Physics (run jointly by LMU Munich and the Max Planck Institute for Quantum Optics) have developed an attosecond electron microscope that allows them to visualize the dispersion of light in time and space, and observe the motions of electrons in atoms.
The most basic of all physical interactions in nature is that between light and matter. This interaction takes place in attosecond times (i.e. billionths of a...
Transistors based on carbon nanostructures: what sounds like a futuristic dream could be reality in just a few years' time. An international research team working with Empa has now succeeded in producing nanotransistors from graphene ribbons that are only a few atoms wide, as reported in the current issue of the trade journal "Nature Communications."
Graphene ribbons that are only a few atoms wide, so-called graphene nanoribbons, have special electrical properties that make them promising candidates for the...
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08.12.2017 | Information Technology
08.12.2017 | Information Technology