Senescence in wild European badgers: the roles of parental age effects and immunosenescence
Lead Research Organisation:
University of Exeter
Department Name: Biosciences
Abstract
It is widely recognised that humans experience age-related declines in immune function, leading to increased susceptibility to infectious disease in old age. While recent research has also revealed immune-system ageing in wild animal populations, its effects on the dynamics of wildlife disease have rarely been investigated. This is significant, as individual variation in disease susceptibility (as would be expected to arise from ageing) can markedly impact the predictions of epidemiological models about disease dynamics and the effectiveness of control measures. This project will therefore utilise an exceptional 40 year field study of an economically-significant disease in its primary wildlife host (bovine tuberculosis [bTB] in the European badger) to investigate the impacts of ageing on disease dynamics and the mechanisms that mediate such links.
Our CASE partners will provide an unparalleled epidemiological and life-history data set arising from a long-running (1976 - present) capture mark recapture (CMR) study of European badgers at Woodchester Park, Glos. Quarterly trapping at 20-25 social groups, coupled with diagnostic bTB tests and immunological and morphological assessments, have yielded life-long records for >3000 known-age badgers. Our ageing research to date (led by Young) has revealed age-related declines in body condition and two key immune traits (ICTL and the IFNy response), and that reduced levels of each are linked with bTB infection. We now propose a novel and timely investigation of the epidemiological consequences of these age-related declines. The project will comprise three work packages:
1. Age-related declines in disease resistance and resilience: test and mechanisms
First, we will build on our existing state-dependent CMR models of bTB in badgers to test for late-life increases in the probability of epidemiological transitions (bTB infection, progression and disease-induced mortality)]. Second, we will investigate candidate mechanisms by testing whether these transitions are also predicted by age-sensitive immune traits (ICTL and the IFNy response) and body condition.
2. Parental age effects on offspring disease resistance and resilience
Biomedical studies suggest that ageing could also have important epidemiological consequences via transgenerational effects on disease susceptibility in offspring. We will therefore investigate, for the first time in a natural population, the impacts of paternal and maternal age at conception (which may act through distinct mechanisms) on the probability of these epidemiological transitions in offspring. We will fit maternal and paternal age (derived from recent genetic parentage assignments) alongside an individual's own age in the state-dependent CMR models developed in Aim 1. We will also investigate candidate mechanisms by testing for maternal and paternal age effects on offspring ICTL, IFNy response and body condition.
3. Does bTB infection exacerbate ageing?
The ageing process itself could in turn be accelerated by bTB infection, given the potential for chronic infections to elevate somatic damage and reduce repair. Despite intense current interest in the causes of variation in ageing trajectories, the impact of disease remains poorly understood. We will therefore investigate the impact of bTB infection on the onset and rates of sex-specific age-related declines in survival, reproductive success and ICTL
Our CASE partners will provide an unparalleled epidemiological and life-history data set arising from a long-running (1976 - present) capture mark recapture (CMR) study of European badgers at Woodchester Park, Glos. Quarterly trapping at 20-25 social groups, coupled with diagnostic bTB tests and immunological and morphological assessments, have yielded life-long records for >3000 known-age badgers. Our ageing research to date (led by Young) has revealed age-related declines in body condition and two key immune traits (ICTL and the IFNy response), and that reduced levels of each are linked with bTB infection. We now propose a novel and timely investigation of the epidemiological consequences of these age-related declines. The project will comprise three work packages:
1. Age-related declines in disease resistance and resilience: test and mechanisms
First, we will build on our existing state-dependent CMR models of bTB in badgers to test for late-life increases in the probability of epidemiological transitions (bTB infection, progression and disease-induced mortality)]. Second, we will investigate candidate mechanisms by testing whether these transitions are also predicted by age-sensitive immune traits (ICTL and the IFNy response) and body condition.
2. Parental age effects on offspring disease resistance and resilience
Biomedical studies suggest that ageing could also have important epidemiological consequences via transgenerational effects on disease susceptibility in offspring. We will therefore investigate, for the first time in a natural population, the impacts of paternal and maternal age at conception (which may act through distinct mechanisms) on the probability of these epidemiological transitions in offspring. We will fit maternal and paternal age (derived from recent genetic parentage assignments) alongside an individual's own age in the state-dependent CMR models developed in Aim 1. We will also investigate candidate mechanisms by testing for maternal and paternal age effects on offspring ICTL, IFNy response and body condition.
3. Does bTB infection exacerbate ageing?
The ageing process itself could in turn be accelerated by bTB infection, given the potential for chronic infections to elevate somatic damage and reduce repair. Despite intense current interest in the causes of variation in ageing trajectories, the impact of disease remains poorly understood. We will therefore investigate the impact of bTB infection on the onset and rates of sex-specific age-related declines in survival, reproductive success and ICTL
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| NE/R012237/1 | 01/10/2017 | 31/03/2023 | |||
| 1921010 | Studentship | NE/R012237/1 | 01/10/2017 | 28/02/2023 | Melanie Weedon |
| NE/W503010/1 | 01/04/2021 | 31/03/2022 | |||
| 1921010 | Studentship | NE/W503010/1 | 01/10/2017 | 28/02/2023 | Melanie Weedon |
| Description | We have investigated and described reproductive senescence in European badgers in greater detail than has been previously published. We now know that maternal age impacts the number of offspring she produces as well as the lifespan and mortality risk of these offspring. We have also begun to collaborate with the Endocrinology lab at Chester Zoo, UK and the lab of Dr Joao Passos at the Mayo Clinic, USA. |
| Exploitation Route | This award is still active so I shall continue to be working on my PhD thesis. Future work once this award has ended could include further academic research in evolutionary ecology and the results may also be applicable to agriculture and the environment in terms of bovine TB management. |
| Sectors | Agriculture, Food and Drink,Environment,Other |