In the natural ecosystem, innumerable species coexist while interacting with each other.In such ecosystems, there are not many dramatic changes in population, such as outbreaks or extinctions of specific species.On the other hand, theoretical studies predict that the greater the number of species of organisms, the more difficult it is to maintain the ecosystem.This gap between theory and empirical suggests that some unknown mechanism is at work.

　Therefore, the research group constructed and analyzed a mathematical model that incorporates the fact that the influence of other species on an organism changes depending on the degree of "success (how prosperous)" of the organism in the biological system.As a result, it became clear that the mechanism to prevent "winning alone" maintains a natural balance.In other words, it was found that when the number of certain species increases (= prospers), the stability of the ecosystem becomes higher when there is an interspecies relationship that causes harm.This study shows that differences in density dependence among beneficial and harmful interspecific relationships are key to maintaining complex ecosystems.

　This result is expected not only to understand the mechanism for maintaining the balance of nature, but also to be applied to the development of efficient diversity conservation methods.

Paper information:[Proceedings of the Royal Society B] Density-dependent interspecific interactions and the complexity-stability relationship