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, Zoolog ical 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.
The authors provide a model of carnivore energetics in relation to predator and prey size, and compare the model predictions with observed estimates of metabolic rates and intake rates taken from animals in the wild. By analyzing the balance between energy intake and expenditure across a range of species, the authors reveal that mammalian carnivores would not be able to exceed a body mass of one ton. Their model predictions are consistent with the data we have. Most mammalian carnivores are relatively small compared with the largest extinct terrestrial herbivorous mammals, such as the Indricothere, which weighed around 15 tons. The largest existing carnivore, the polar bear, is only around half a ton, while the largest known extinct carnivores, such as the short-faced bear, weighed around one ton. The authors also note that the largest terrestrial non-mammalian predators, such as Giganotosaurus and Tyrannosaurs, may have achieved their massive size by having a lower metabolic rate. Indeed, previous estimates of total metabolic rate for these species are similar to those of a mammal weighing about a ton.
We know that the largest carnivores that exist today are particularly vulnerable to threats imposed by humans and have been shown to have higher rates of extinction in the fossil record than smaller species even prior to the evolution of man. Carnivores at the upper limits of body mass would have been heavily reliant on abundant large prey to both minimize energy expenditure and maintain high rates of energy intake. Slight environmental perturbations, anthropogenic or otherwise, leading to lower prey availability, could readily upset this energy balance. It may have also contributed to the extinction of the largest carnivores and explain why the largest modern mammalian carnivores are so rare and vulnerable today.
Citation: Carbone C, Teacher A, Rowcliffe JM (2007) The costs of carnivory. PLoS Biol 5(2): e22. doi:10.1371/journal.pbio.0050022.
Andrew Hyde | alfa
Bacteria as pacemaker for the intestine
22.11.2017 | Christian-Albrechts-Universität zu Kiel
Researchers identify how bacterium survives in oxygen-poor environments
22.11.2017 | Columbia University
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
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