Carnivores are some of the widest ranging terrestrial mammals for their size, and this affects their energy intake and needs. This difference is also played out in the different hunting strategies of small and large carnivores. Smaller species less than 15-20 kg in weight specialize on very small vertebrates and invertebrates, which weigh a small fraction of their own weight, whereas larger species (>15-20 kg) specialize on large vertebrate prey near their own mass. While carnivores around the size of a lynx or larger can obtain higher net energy intake by switching to relatively large prey, the difficulty of catching and subduing these animals means that a large-prey specialist would expend twice as much energy as a small-prey specialist of equivalent body size. In a new article published by PLoS Biology, Dr. Chris Carbone and colleagues from the Institute of Zoology, Zoological Society of London reveal how this relationship might have led to the extinction of large carnivores in the past and why our largest modern mammalian carnivores are so threatened.
New scientific research may close a major loophole in the RNA world hypothesis, the idea that ribonucleic acid -- not the fabled DNA that makes up genes in people and other animals -- was the key to life's emergence on Earth 4.6 billion years ago. That hypothesis states that RNA catalyzed all the biochemical reactions necessary to produce living organisms. Only later were those self-replicating RNA units joined by organisms based on DNA, which evolved into more advanced forms of life.
Bacteria in the world's oceans can efficiently exploit solar energy to grow, thanks to a unique light-capturing pigment. This discovery was made by researchers at University of Kalmar in Sweden, in collaboration with researchers in Gothenburg, Sweden, and Spain. The findings are described in an article in the journal Nature.
"It was long thought that algae were the only organisms in the seas that could use sunlight to grow," says Jarone Pinhassi, a researcher in Marine Microbiology at Kalmar University College. These microscopic algae carry out the same process as green plants on land, namely, photosynthesis with the help of chlorophyll.
In 2000 scientists in the U.S. found for the first time that many marine bacteria have a gene in their DNA that codes for a new type of light-capturing pigment: proteorhodopsin.
Proteorhodopsin is related to the pigment in the retina that enables humans to see colors. It should be possible for this pigment to enable marine bacteria to capture solar light to generate energy, but until now it had not been possible to confirm this hypothesis.
Animated films produced by children offer wide-ranging insights into how the younger generation see the world around them. This was the conclusion of an extensive project run by the "Zoom" Children's Museum in Vienna, Austria. During a number of workshops, children and young people were given the opportunity to make their own animated films. The messages these films contain have now been interpreted as part of the project, which is supported by the Austrian Science Fund (FWF). Initial results indicate that the young generation is in two minds about technological progress and is extremely worried about our impact on the environment. The study also showed that gender stereotypes are far from being overcome.