Determinants of Diversity (continued)

Determinants of Diversity (First Blog)

Hot and relevant news! Can we use this in the metaphor for economy? No reason why not, it mostly just confirms long-standing observations that diverse systems are stable.

Stefano Allesina and Si Tang, both of the University of Chicago published an article in Nature online (Feb 19) that revises the peculiarly troubling equation posited by Robert May (a physicist) in 1972. May’s simple model described the relationship between diversity and stability in a theoretical ecosystem based on random interactions among species. Ecologists had observed richer, more diverse environments to be inherently more stable while May’s model suggested that more species creates less stability.

Example of a highly diverse jungle; trees are the organic matrix in this system

I must admit at the time I was reminded of the engineering work that demonstrated bumble bees could not fly, and wondered why he had bothered to publish something that so obviously did not match the observations. My own work on organic matrices argued that more diversity tended to produce more stability, but only in the instances where there was an organic matrix that provided for extensive interactions that included but were not just predator-prey interactions and that were mediated by an organic matrix, not just a physical or non-biological matrix.

However, it turns out that May’s work could be useful and that it was based on some incorrect assumptions which Allesina and Tang (Nature Feb 19) were able to adjust. The results of Allesina and Tang’s network analyses demonstrate that stability in complex ecosystems is determined by the type of interaction among species including predation, competition, and mutualism as well as the strength of those interactions. They further determined that a stable system could comprise any number of species. If we add to that work the idea of an organic matrix that allows a diverse system to develop, we have a model that both describes and predicts at least some of the observed development, behaviour, and nature of complex biological ecosystems.

In an upcoming blog, I will investigate how we can use this in an economic system.

Leave a Reply

Your email address will not be published. Required fields are marked *