Evolution of Stable Ecosystems in Populations of Digital Organisms

Competition for resources has long been believed to be fundamental to the evolution of diversity. However, the difficulty of working with natural ecosystems has meant that this theory has rarely been tested. Here, we use the Avida experimental platform to demonstrate the evolution of ecosystems composed of digital organisms. We show that stable ecosystems are formed during evolution in an environment where organisms must compete for limiting resources. Stable coexistence was not observed in environments where resource levels were not limiting, suggesting that competition for resources was responsible for coexistence. To test this, we restarted populations evolved in the resource-limited environment but increased resource levels to be non-limiting. In this environment, ecosystems previously supporting multiple genotypes could maintain only a single genotype. These results demonstrate the utility of the Avida platform for addressing ecological questions and demonstrate its potential in addressing questions involving ecosystem-level processes.