I am developing and applying biodemographic methods. Specifically, my research is focused on

I refer to improvement in individual performance beyond sexual maturity caused by learning, development, or changes in dominance status as post-maturational enhancement.

Traditional theories argue that the strength of selection against phenotypic deterioration should decrease progressively with age after maturity. Using optimization models, Vaupel et al (2004, Theoretical Population Biology 65: 339-351) and Baudisch (2008, Inevitable Aging? Springer) showed that performance could however continue to increase for some time after maturity and argued that senescence is not inevitable. A growing number of studies have provided anecdotal support for the new theory by reporting improvements in age-specific survival probability and fertility after maturity, although these results have not been used to formally test this theory. I propose to challenge the theory with data to provide insight on selection for post-maturational enhancement. In particular I hope to investigate the processes that have shaped this particular strategy. Although there is mounting evidence for post-maturational enhancement it does not appear to be sufficient for most species to indefinitely delay senescence, and one pressing question beyond characterizing the prevalence and strength of post-maturational enhancement is for how long a period does it last. Second, does post-maturational enhancement occur in both survival and fertility, in particular the probability of reproduction, the number of eggs, the number of hatchlings or the number of fledglings?

There are trade-offs at multiple levels of biological organization that shape all aspects of life-history. Different fields tend to focus on one level: demographers and evolutionary ecologists often characterize trade-offs at the phenotypic and demographic level using optimization methods, while quantitative geneticists characterize trade-offs using genetic variance-covariance matrices. After I have characterized the prevalence and magnitude of post-maturational enhancement across a range of populations I hope to examine how working at different levels of biological organization provide insight into the processes that have moulded the evolution of post-maturational enhancement. Clearly this research will involve a mixture of statistical modeling and theory development. Long-lived birds offer an ideal group of organisms to address these questions. Currently I am identifying data sets that would allow me to address one or both aspects of my planned research.

Tim Coulson from Imperial College London and James W. Vaupel from the Max Planck Institute for Demographic Research (MPIDR) jointly supervise my project.

I am funded by a MPIDR studentship.