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Content archived on 2023-03-06

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Scientists uncover key to food web stability

An international team of scientists has worked out the rules that govern the stability of food webs. The study, which was partly funded by the EU, is published in the journal Science and should help those involved in conservation work. All plants and animals are part of compl...

An international team of scientists has worked out the rules that govern the stability of food webs. The study, which was partly funded by the EU, is published in the journal Science and should help those involved in conservation work. All plants and animals are part of complex, interwoven food chains, in which species can be both predator and prey. Understanding the factors that influence the stability of these food webs is important, especially in the light of growing concerns regarding the stability of natural systems. Food web stability refers to the relative permanence and strength of the links between the different species in a system. In a stable system, the interactions remain unchanged for a long time. Earlier studies of the factors influencing food web stability tended to oversimplify food webs and limit the number of influencing factors. In this study, scientists from Austria, Germany and the US used a computing approach called 'generalised modelling' to analyse billions of food webs (for comparison, earlier research only looked at thousands of food webs). Generalised modelling allows researchers to analyse the influence of countless factors on complex systems. As such it can also be used to study human metabolism or the control of gene activity, for example. 'With the help of so-called generalised models we calculate whether a given food web can, in principle, be stable; in other words, whether the species involved can live together in the long term,' explained lead author Thilo Gross of the Max Planck Institute for the Physics of Complex Systems in Germany. 'In this way we can estimate which parameters keep ecosystems stable and which ones bring them out of balance.' The team succeeded in identifying two universal rules of food web stability. 'Large predators stabilise communities if they feed off many different prey species,' said Ulf Dieckmann of the International Institute for Applied Systems Analysis in Austria. 'At the same time, ecosystems are more stable if prey species in the middle of the food chain provide food to several species of predator.' The researchers also discovered that smaller food webs behave quite differently to food webs with many species. Small food webs are more stable when there are very strong links between some species and weak links between others. In larger food webs the opposite applies; extremely strong or weak predator-prey relationships should therefore be rarer in nature in large food webs.

Countries

Austria, Germany