Comparative studies of leaf evolution in the California Chaparral
In an article published in the May 2004 issue of The American Naturalist, David D. Ackerly (Stanford University) compares the evolution of twelve lineages of the California Chaparral.
Which came first--trait or environment? This question lies at the heart of the study of adaptation by natural selection. In Mediterranean-type climates, many woody plants have small, tough, evergreen leaves (dubbed sclerophylls) which allow them to photosynthesize during the cool wet winters and survive the hot summer dry season. This paper presents the first comparative test of alternative hypotheses to explain these shared features. Did these traits evolve independently in different lineages, in response to the unique Mediterranean-type climate? Alternatively, did the traits evolve first in response to other factors, subsequently promoting the success of these lineages when summer drought conditions arose in the past few million years? Twelve independent plant lineages of the California chaparral were examined, using comparative methods that combine new phylogenetic information and statistical techniques. Only four of the twelve lineages showed the pattern expected if the leaves had evolved to suit the Mediterranean-type climate. In the other cases, the leaf traits appear to be ancestral characteristics of these lineages that predate the climatic conditions. These results, together with biogeographic and paleobotanical information, highlight the importance of ecological processes in concert with adaptive evolution in shaping the form
Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society
Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
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28.04.2017 | Medical Engineering
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28.04.2017 | Life Sciences