Biologists have long argued about how birds evolved the ability to fly, because it is not immediately evident what improvement in fitness would result from ancestral, partly evolved wings. Two theories have recently dominated the debate: one postulates that flight evolved in tree-dwelling ancestors that used their forelimbs to help them glide, while the other considers ancestral birds to be terrestrial dinosaurs that developed powered flight from the ground up.
An article by Kenneth P. Dial and two co-authors in the May 2006 issue of BioScience summarizes experimental evidence indicating that ancestral protobirds incapable of flight could have used their protowings to improve hindlimb traction and thus better navigate steep slopes and obstructions. By using their protowings in this way, they would presumably have had an advantage when pursuing prey and escaping from predators.
Dial and colleagues performed experiments on several species of juvenile galliform (chicken-like) birds, concentrating on chukar partridges. Chukars can run 12 hours after hatching, but they cannot fly until they are about a week old. Even before they are able to fly, however, the birds flap their developing wings in a characteristic way while running, which improves their ability to climb steep slopes and even vertical surfaces. Dial and colleagues have named this form of locomotion "wing-assisted Iincline running" (WAIR). After they are able to fly, chukars often use WAIR in preference to flying to gain elevated terrain, and exhausted birds always resort to WAIR.
Dial and colleagues describe experiments showing that if the surface area of chukar wings is reduced by plucking or trimming the feathers, WAIR becomes less effective for climbing slopes. Dial and colleagues propose that incipiently feathered forelimbs of bipedal protobirds may have provided the same advantages for incline running as have now been demonstrated in living juvenile birds. Their work thus supports a new theory about the evolution of flight in birds. WAIR, which the authors believe to be widespread in birds, appears to offer an answer to the question first posed by St. George Jackson Mivart in 1871: "What use is half a wing?"
Donna Royston | EurekAlert!
Two Group A Streptococcus genes linked to 'flesh-eating' bacterial infections
25.09.2017 | University of Maryland
Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden
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...
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...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
25.09.2017 | Power and Electrical Engineering
25.09.2017 | Health and Medicine
25.09.2017 | Physics and Astronomy