Food webs, or ecological networks representing consumer-resource relationships, are widely used tools for studying relationships between ecosystem stability, resilience, and diversity. Combined with dynamic models, food webs have been used to understand how many types of ecological interactions play a role in shaping ecosystem structure. However, the strengths and nature of the interactions can change over longer time scales as ecosystems evolve and undergo natural changes in composition with species adapting, going extinct, and new species emerging. In this talk I will present an evolutionary game theory model that combines deterministic ecological dynamics with a stochastic speciation process and discuss patterns in abundance, extinction, trait distribution, and structural changes that emerge as food webs evolve.
Many of the simulated food webs in this study persist over hundreds of speciation events, exhibiting varying degrees of diversity and connectance over time. During the food web evolution process, some food webs steadily increase in richness and exhibit infrequent extinction events. Others exhibit cascading extinctions of many species over a short period, and in some cases the food webs crash entirely. Resulting food webs often also have properties that are in the range of natural food webs. I will show how the distributions of traits change over time and in relation to extinction events, and describe the properties of food webs that are vulnerable to cascading extinctions. This work demonstrates how a few relatively simple evolutionary and ecological assumptions can be integrated to model ecological change and produce complex ecosystem structures that can be used to study vulnerability and stability of natural systems.