The genetic and physiological basis of ageing in a wild mammal

Supervisors: Daniel Nussey, Tom McNeilly

Project description:

Our understanding of the genetic and physiological mechanisms underpinning the ageing process has been transformed by the study of short-lived model organisms in the laboratory. This research has identified common genetically controlled pathways which influence lifespan and ageing rates across distantly related species under lab conditions. However, it remains to be determined whether variation in these pathways plays a significant role in organismal health and fitness under challenging natural conditions representative of those under which species’ lifespans evolved. There is now overwhelming evidence that ageing is detectable in wild vertebrate systems and that the process can have significant fitness costs [1]. However, the important question of whether the same genetic pathways and physiological processes identified in studies of laboratory models and humans are involved in ageing in wild populations remains to be addressed.

The long-term study of wild Soay sheep on the remote St Kilda archipelago has monitored and sampled thousands of individuals continuously from birth to death since 1985. This rich and detailed study system reveals strong evidence for age-related declines in key health and fitness traits [2]. As part of an ongoing multi-disciplinary collaboration between field ecologists, geneticists, veterinary scientists and cellular biologists, we have been developing tools to assay key biomarkers of ageing using samples collected as part of this long-term study. For example, as part of a recently completed BBSRC-EASTBIO studentship, we demonstrated sex- and age-related variation across a suite of immunological phenotypes and in leukocyte telomere length in this wild population, which were comparable to those observed in humans [3]. 

This PhD project will utilise the wealth of longitudinal phenotypic, environmental, physiological and genomic data available from the long-term study. The student will address how early-life environment and genetics shape the ageing process in a wild mammal in unprecedented detail. Key questions that would be addressed include: 

- How heritable are lifespan and ageing in this system and are particular genes that are associated with ageing in model systems involved?

- How do early life environmental conditions and early life reproductive investment influence age-related declines in immunity, telomere length, body mass and fitness?

The project will be largely analytical and would suit candidates with some background in statistics and the use of R, and an interest in working with large, complex data sets. Relevant training in statistics will be provided as part of the project, and there will be opportunities to gain experience with both research in the field on St Kilda and in assaying biomarkers of ageing and immunity in the laboratory.


[1] Nussey et al (2013) Senescence in natural populations of animals: Widespread evidence and its implications for bio-gerontology. Ageing Research Reviews 112, 214-225. 

[2] Hayward et al (2015) Asynchrony of senescence among phenotypic traits in a wild mammal population. Experimental Gerontology 71, 56-68.

[3] Watson et al (2017) Sex differences in leucocyte telomere length in a free-living mammal. Molecular Ecology 26, 3230-3240.