santa barbara, Calif. – The old theory in ecology is that every ecosystem, Small animal species will be more populous than large species. You need a proven point of Summer Picnic: your Grill can end attract thousands of tiny ants — but only a few Chipmunks, Rex.
Equations based on ecological theories as scientists one assistance and natural resource managers predict abundance and health of the population of animals, such as to understand which species are naturally rare and about how rare it is. But you reanalyzing published this week in the journal Science reviewed the specific rule.
"A theory really should also say ' depending on the position of the food chain", "says Ryan Hechinger, lead Author of studies and associate research scientist at the University of California at Santa Barbara.
The population of animals are often limited by their supply of food and metabolic rate. Tiny animal burns less calories than large animal, "says Hechinger, so you need to consume less food than the large animals in order to stay alive. "This is why small animals are usually more often than the big ones" adds Hechinger. "However, it is also important to the food chain. There is less food to travel higher up the food chain, which you can go. This is why the top consumers as mountain lions are relatively rare. "
But ecologists know that although the representativity, the parasites also feed high up in the food chain. "For example, tapeworm, which infests feeds deer, in the same place in the food chain as a mountain lion," says Hechinger. "So we wondered whether a parasite population may be less common you expect the fed to the old rule."
Examine whether the tiny parasites exhibit patterns for abundance of top consumers, Hechinger and colleagues from the University of California-Santa Barbara, U.S. Geological Survey, Princeton University, Santa Fe Institute and the University of New Mexico Albuquerque studied three estuarine ecosystems in Southern California and Baja California. Counted and weighed parasites and other animals before confirmation that the parasites were in fact less populated than other similar sized animals.
"But once we was a contributory factor in the food chain, single, improved the equation was able to explain the observed patterns of population both parasites and other animals," says USGS ecologist Kevin Lafferty, testing on a second author.
The findings also led to another revelation of profound: regardless of the volume of the body on the species, species occupying the same position in the chain have the same rate of biomass production — annual yields of their weight. With this logic of population biomass and biomass tapeworm deer mountain lion population may increase at about the same.
Whether Lafferty revised theory has broad implications for researchers and managers, "he says. "We can now more easily predict the abundance and biomass production of all species of the ecosystem — including parasites."
The study is available online.
More information on research a parasite by the USGS ecologist Kevin Lafferty.
The images accompanying this release messages are available online.
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