The evolution and stability of cooperation between species: insights from model ant-plant symbioses

Widespread in nature, mutualistic associations –cooperative interactions between unrelated species– are linked to major evolutionary transitions, and are pivotal for ecosystem functioning. The evolution and subsequent stability of mutualisms have long been a riddle: while they are thought to be prone to breakdown, some have persisted for millions of years. In this talk, I will focus on mutualistic dependence – the degree to which a partner is dependent on the interaction for survival or reproduction. Drawing from examples from my research using ant/plant symbioses, I will show that (i) mutualistic dependence is critical in determining the stability of mutualism over the geologic scale, (ii) how highly dependent and specialized mutualisms deal with exploitation and (iii) how cooperation is maintained in low-dependence multi-partner mutualisms.