Mechanisms and Evolution of Post-Reproductive Lifespan

Post-reproductive lifespan (PRL) is a life history stage found in distantly related taxa in both vertebrates and invertebrates. Ultimate explanations for the evolution of PRL remain contentious, and the proximate mechanisms which facilitate and regulate PRL are poorly understood. The potential influences of life history traits, physiological condition and ecological constraints on the occurrence of PRL are not known. In social insects, PRL may represent a stage in the transition from simple cooperative sociality (where workers retain reproductive potential) to pre-imaginal caste determination, a defining feature of complex eusociality. This project will investigate reproductive potential and PRL in the sister species Polistes lanio and Polistes canadensis, two simply eusocial tropical paper wasp. The workers of tropical Polistes species display loss of reproductive potential with age. I will determine the functional consequences of PRL on 'risky' altruistic behaviour, reproductive conflict and reproductive physiology through field experiments, behavioural analyses and examination in the lab. Using transcriptomics and gene ontology, I will identify potential molecular mechanisms associated with PRL in this invertebrate system. Understanding the molecular and physiological mechanisms and the phenotypic consequences of PRL will provide insights into the evolution of reproductive plasticity and the predetermination of caste identity in complex eusociality.