There is a phenomenon of chaos everywhere, from the weather systems to the planets. Chaos in the living world was thought to be rare. A new analysis shows that there is more chaos in the world than thought.
When she looked through the scientific literature for recent studies on chaos in the environment, she found that no one had ever done a quantitative analysis of it. Rogers is a research ecologist at the University of California, Santa Cruz. 'I can't believe no one's done this'
She decided to do it her way. Rogers and her colleagues found that chaos was present in a third of the 170 sets of time- dependent data they analyzed. They found that certain groups of organisms, like plankton, insects and algae, were more prone to chaos than larger organisms.
Stephan Munch is an evolutionary ecologist at Santa Cruz and a co-author of the study. It is possible and necessary to build more complex population models in order to protect vulnerable species, according to their findings.
When ecology was first recognized as a formal science in the 19th century, it was assumed that nature follows the same rules as a mechanical clock. Scientists could predict the outcome if they could measure the right variables.
George Sugihara, who was not involved in the new research, said that the world is more chaotic because of it. Predictability is reflected in chaos. A system is said to be stable if it doesn't change much over a long period of time. A chaotic system may be predictable over a short period but is subject to dramatic shifts the further out you go.
The weather is an example of a chaotic system. A summer breeze over the open ocean probably won't affect tomorrow's forecast, but it could theoretically send a Hurricane plowing into the Caribbean in a few weeks
Ecologists were flirting with the idea of chaos in the 70s when Robert May developed a revolutionary tool. Chaos creeps into simple models of population growth in this branching diagram. Ecologists assumed that species populations in nature would rise and fall chaotically since the survival of organisms is affected so much by the weather. Logistic maps became standard in the field as theorists sought to explain population fluctuations in organisms that cause red tides.
By the early '90s, ecologists had amassed enough time-series data sets to test their ideas. The chaos didn't seem to be there Only a small percentage of the populations seemed to change chaotically. By the mid- 1990s, theories of chaos were no longer used in science.
The new results show that the older work missed a place where chaos was hiding. The population size of one species over time was used as a model for detecting chaos. They didn't consider the changes in real-world factors that might affect populations. They didn't capture why the populations changed, but how they changed.
A professor of ecology and evolutionary biology at the University of Michigan, who was not involved in the study, said that Rogers and Munch looked forchaos in a more sensible way. They analyzed 172 time series of different organisms' populations as models with as many as six dimensions rather than just one and left room for the influence of environmental factors. They could look at the one-dimensional representation of the population shifts to see if chaotic patterns were present. It is possible that more rain is linked to population increases or decreases, but only after a few years.
The signatures of chaotic interactions were found in the data for 34% of the species. The population changes for the species did not seem chaotic at first, but the relationship of the numbers to underlying factors was more important. Whatever environmental factors were responsible for the chaos, their fingerprints were on the data.
The inverse relationship between body size and population dynamics was discovered by the researchers. Small organisms that breed more often are also more affected by outside variables. Populations of diatoms with generations of around 15 hours show more chaos than packs of wolves.
That doesn't mean that wolves are stable. There is a chance that we are not seeing chaos because we don't have enough data to see it. He and Rogers think that because of the constraints of their data, their models might underestimate how much chaos is present.
New results may be important for the preservation of the environment. Predicting toxic algal blooms could be done better by improved models with the right element of chaos. It is possible to meaningfully predict population size by considering chaos. He thinks that the issue should be in people's minds.
He and King don't want to place too much faith in these models. King said that the classical concept of chaos is based on the assumption that chaotic fluctuations are a departure from a predictable norm. Climate change is making most real-world ecosystems unstable in the short term. Scientists will have to be aware of this baseline even though they take many dimensions into account.
Chaos is an important step in the right direction. "I think it's really exciting," said the man. It doesn't jive with the way we think about ecology.
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