Communities in nature are likely to be a lot more sensitive to change than previously thought, according to a new study at Rice University.
The study, which appears this week in Nature Communications, shows that scientists concerned about human influence on the biosphere need to take a deeper look at how altering the dynamics of a population — for example, by removing large members of a species through overfishing — can have measurable consequences, said Rice ecologist Volker Rudolf.
“Natural communities are increasingly altered through human impact, and ecologists have long strived to determine how these changes influence communities,” Rudolf said. He noted the disappearance of a species is the most extreme but not the only cause of biodiversity loss.
“That’s the last thing that happens after you mess up the entire ecosystem for a long period of time,” he said. By then, changes forced upon the structure of a population — such as the ratio of young to old in a species — have already been felt up and down the food chain.
Rudolf suspected species play various roles and their effects on the environment change as they progress through their lifecycles, to the degree that altering these life “stages” within a species could have a significant impact. He and Rice graduate student Nick Rasmussen made a considerable effort to prove it.
For the painstaking experiments that started in 2009, Rudolf, Rasmussen and their colleagues chose dragonflies and water-diving beetles to represent species that have major impact on their respective communities — in this case, fishless ponds — and then created dozens of miniature environments to analyze that impact. Manipulating the presence of different developmental stages within a predator species in each pond helped the researchers determine that such changes did alter the dynamics of complex ecosystems in a measurable way.
“Other than being the largest and most voracious predators in these communities, they’re totally different,” Rudolf said of the apex predators. “We figured if we saw any generalities across these two species, then there’s something to our theory.”
They found that altering which classes of size were present in a population also altered the structure of the entire community and ultimately how the whole ecosystem functioned. Also important, Rudolf said, was that changing the structure of populations sometimes had bigger effects on the ecosystem than changing the predator species.
The results, he said, “challenge classical assumptions and studies that say we can make predictions by assuming that all individuals of a species are the same. You don’t expect a toddler to do the same thing as a grownup, and the same is the case for animals.”
The study could also explain why such human activities as size-selective harvesting can alter the structure of entire food webs in some ocean systems, even when no species had gone extinct and the total biomass of the targeted fish remained the same, he said.
“While these changes would be hard to predict by the classical approach, our results suggests such changes are expected when human activities alter the population structure of keystone species in an ecosystem,” Rudolf said. “Thus, natural ecosystems are likely to be much more fragile then we previously thought.”Rice University
David Ruth | EurekAlert!
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...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences