Loss and deterioraton of indigenous habitat increasingly affect natural populations worldwide. As a result of these processes, new selection pressures are imposed upon organisms, increasing local extinction rates. Simultaneously, reduced movement among remnant patches lowers colonisation rates and affects demographic and genetic population parameters. Yet, organisms with comparable life histories often respond to habitat disturbance in various ways. Why so is a matter of great importance to evolutionists and conservationists alike.
To address the question what factors determine the persistence of species in fragmented habitats, an international team led by Belgian ecologist Luc Lens studied the relative impacts of forest deterioration and fragmentation on the persistence of eight forest-restricted bird species within 430 ha of rainforest remnants in south-east Kenya. Three species are endemic to the Taita Hills, which is part of the Eastern Arc biodiversity hotspot. Over the past decades, the indigenous forest has been reduced to 12 patches, of which only the three largest ones (94-179 ha) are inhabited by all study species. The nine other remnants are tiny (1-8 ha) and heavily disturbed, and host breeding populations of a subset of species only.
The researchers used data collected during six years of trapping, marking, and recapturing more than 3,000 birds to estimate species-specific ability to move among the forest remnants. To estimate stress tolerance, the team relied on earlier studies showing that when birds are under stress, bones in the hind limbs grow longer on one side than on the other. It was determined which species suffered the most stress by comparing measurements of modern birds to those of museum specimens captured when the forest was relatively undisturbed. Based on these estimates, it was shown that more mobile species occupied a higher proportion of patches than expected from their estimated stress sensitivity. Likewise, less sensitive species occupied a higher proportion of patches than predicted from their estimated level of mobility. Together, dispersal rate and change in asymmetry explained an astonishing 88% of the observed variation in patch occupancy between the eight study species.
Luc Lens | alfa
Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen
A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
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...
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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