Supervised by:

Pierre Legagneux (Regular Member (Co-researcher))

Co-supervised by:

Gilles Gauthier (Regular Member (Co-researcher))

Research project description

Combining physiology, population dynamics and evolution to shed light on biological enigma: the determinants of senescence in vertebrates

Introduction

Senescence is the set of negative consequences of ageing, notably illustrated by a decrease in an individual’s reproduction and survival probability with age. This phenomenon is well known, though not yet totally understood in humans, and is expected to be largely widespread in animal species. However, recent research has shown that senescence is far from being as widespread in the living world. In fact, numerous species do not seem to show signs of decreased reproduction and survival with age. This questions previous theories and highlights the need to study senescence with a new angle and different approaches. Indeed, it raises the need to better understand the determining factors, be it age or other variables, to better apprehend its impact on population dynamics. This project will allow us to both clarify a fundamental biological question and refine our understanding of greater snow goose populations, a structurally important species for arctic ecosystems.

Objectives

This project will study the senescence of the greater snow goose using demographic data on survival and reproduction, looking at the link between these parameters and age as well as other variables which could potentially affect an individual’s performance. This project could be divided into three principal objectives: First, I will establish the relationships between reproduction, survival, and age in the greater snow goose, using multi-event models. Second, I will determine the link between age and physiological variables (indicators of body condition, telomere length and microbiome). This will enable us to identify factors which could explain reproductive and survival senescence differently. I will also compare models explaining senescence using age or using the other physiological factors in order to better describe the effects observed at the demographic scale.

Study Sites

The greater snow goose winters along the American east coast and reproduces in the Arctic in the North of Canada during the summer. During this summer, the geese are banded on Bylot Island, Nunavut, where the colony holds 20% of the Canadian breeding population. This colony has been monitored for more than 30 years and we have marked more than 100.000 individuals.

Material and methods

We now have rich data from the ecological monitoring of Bylot Island over the last 30 years which enable a fine analysis of senescence and its impact on the dynamic of the population. To establish the effects of age or of the other physiological variables on the population dynamics, multi-event capture-recapture models will be used, with which survival rates and reproduction rates will be estimated. The data for the study of the physiological variables will come from the analysis of blood and fecal samples.

Expected results

According to similar studies done on other species in the literature, a decrease in reproduction and survival with age can be expected. I also expect age to have an effect on the physiological variables of interest, notably a shortening of telomeres and a change in microbiome with age. Thus, these variables should have a negative effect on survival and reproduction. However, according to preliminary results, there seems to be an important individual variability in the effect of age on these physiological variables as well as on survival and reproduction. It could therefore be possible that these physiological variables better explain the decrease in reproduction and survival than age.

Research Site Coordinates