Some 100 species of birds are what scientists call "obligate brood parasites"--instead of building nests and raising their own young, they lay their eggs in the nests of other species and let those birds do the hard work of parenting for them. The black-headed duck of South America is one of these, but it stands out from all the others in a striking way. Black-headed ducks dont need any parental care other than incubation for their eggs--the ducklings leave the nest one day after hatching and paddle off into the reeds to fend for themselves.
"There doesnt seem to be much if any cost to the host species, so you wouldnt expect there to be much pressure on the hosts to evolve defenses against this kind of parasitism," said Bruce Lyon, a professor of ecology and evolutionary biology at the University of California, Santa Cruz.
When Lyon and John Eadie of UC Davis set out to study the black-headed ducks, they expected to find a highly successful brood parasite, unopposed by the antagonistic strategies that host species deploy against more costly parasites like cuckoos and cowbirds. Instead, they found that black-headed duck eggs are often rejected from host nests, and it took four years of detailed field research to figure out why. Lyon and Eadie published their findings in the November 18 issue of the journal Nature. The key breakthrough was their discovery that each of the black-headed ducks two main host species--the red-gartered coot and red-fronted coot--were busy parasitizing the nests of their own species. The black-headed ducks were being thwarted by defenses that had evolved as a result of brood parasitism among the coots themselves.
Tim Stephens | EurekAlert!
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22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden
The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie
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.
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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...
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Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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