14 DAY TRIAL // A new scientific breakthrough finally makes it possible for scientists to create more precise computer models for how the various species living in an ecosystem interact. Thus far, progress in this area has been stymied by an apparent paradox, which halted further advancements for a long time.
Over the years, scientists have figured out that we are currently heading towards the sixth global extinction event. Figuring out how this will occur requires a deeper understanding of the intricate patterns of relationships that govern the interactions of species in today's ecosystems.
But the sheer complexity of such interactions is staggering. As if that were not enough, scientists studying these things also had to account for a conclusion that previous computer models kept spitting out, which is that complex ecosystems cannot persist.
Obviously, they do persist. Over the past 500 million years or so, habitats such as coral reefs, forests, jungles and so on have been home to thousands of interacting species. But every time researchers placed these data in a computer model, the simulation predicted the ultimate decay of the ecosystem.
A similar type of conclusion also plagues the field of astronomy. The Big Bang model explains the formation of the Universe, but does not allow for the existence of galaxies and planets. Scientists struggling to explain this believe that normal matter managed to defeat antimatter in an ancient battle.
Investigators from the University of Chicago, led by Stefano Allesina and Si Tang, managed to provide a solution for the apparent paradox concerning ecosystems. The fallacy was discovered more than 40 years ago, and has remained a mystery until now.
Their research, which was sponsored by the US National Science Foundation (NSF), was published in this week's issue of the top scientific journal Nature. The main conclusion is that large ecosystems featuring many species do not necessarily have to be extremely unstable, as previously thought.
The old “model assumes that any two species in a large ecological network interact with one another at random, and without any consideration of the specific type of interaction between them, whether it is a predator-prey relationship, a mutualistic relationship or a competitive relationship,” Allesina explains.
What the new study reveals is that, in addition to interacting with each other as mutualists or competitors, species in an ecosystem also consume each other. This key factor may help explain why a habitat does not experience extinctions regularly, as the past models predicted.
“The results of Allesina and Tang's network analyses are important, because they show that the stability properties of complex ecological systems are determined by the type of interaction among species (predation, competition, mutualism) and the strength of those interactions,” NSF program director David Spiller concludes.