Unpicking the demographic causes and consequences of individual differences

Demographic models are widely used to investigate how variation in survival and reproduction (‘demography’) drive population dynamics and life history evolution. Methods to explore how population processes depend on environmental factors and age- or stage-dependent demographic variation are well-established. More recently, using integral projection models (IPMs), researchers have also begun to explore how among-individual trait variation modulates population processes. However, these powerful tools typically consider a limited range of traits (almost always body size!) and are seldom used outside the traditional boundaries of population ecology.
This multidisciplinary project will use demographic methods to investigate the genetic and physiological basis of demographic variation, and in turn, explore how trait-linked demographic processes influence population dynamics. The project will use data from the long-term study of Soay sheep on St Kilda, Scotland. Arguably the best long-term ecological dataset in the world, the Soay project has amassed an unparalleled demographic, genomic, and physiological data set during more than 30 years of intensive data collection. This is an open-ended project with considerable scope for the successful candidate to shape their own research agenda. Two potential research strands are:
Demographically informed genomic prediction --- Genomic prediction is a relatively new tool to that predicts the genetic value of individual traits. The approach is currently being used by Prof Slate to examine the genetic response to selection on morphological traits. A significant difficulty with applying genomic prediction in natural populations is the stochastic nature of individual life trajectories: the observed fitness of an individual is largely a consequence of the chance demographic events and environmental conditions they experience during their life. By using a demographic model, we will derive the expected fitness of an individual under standardised environmental conditions to significantly improve the performance of genomic prediction in the wild.
Physiological drivers of demographic variation --- Demographic methods are often used to investigate how dynamic variation in morphological traits impacts upon vital rates and population dynamics. However, the interplay between demography and physiological variation is largely unstudied. Prof Nussey has accumulated an extensive dataset of ageing (telomeres) and immune function (antibodies) biomarkers. Putative demography-fitness associations have already been identified, but little is known about the population-level consequences of this variation. We will use these data to explore how among individual variation in physiological status influences population dynamics.
The PhD will suit a motivated student excited by the opportunity to work across traditional discipline boundaries, using state-of-the-art statistical and population modelling techniques. Biologists with a quantitative Masters or candidates with a mathematics or statistics background who wish to make the transition to a career in mathematical biology are encouraged to apply. Potential candidates are strongly encouraged to email Dr Dylan Childs ([Email Address Removed]) with informal enquiries.