| Summary: | Predation is a key selective force driving prey trait evolution. Yet, the extent to which predator-consumptive and predation risk effects shape phenotypes is still poorly understood. Since predation risk increases the cost of current reproduction, long-lived prey are predicted to prioritize survival and future reproduction by reducing reproductive investment under high predation risk (e.g., through changes in life-history, behaviour, physiology or morphology). However, the relative roles played by adaptive plastic responses (i.e., withinindividual phenotypic variation) and selective processes (i.e., among-individual phenotypic variation) in allowing populations and individuals to persist under fluctuating predation threat in the wild have been overlooked. In my thesis, I shed light on these knowledge gaps by evaluating the responses of a sea duck species, the common eider Somateria mollissima, to fluctuating predation risk from their native predator, the white-tailed eagle Haliaeetus albicilla. I focused on adjustments of behavioural and physiological traits to the recovery of white-tailed eagles in southwestern Finland. As a longlived species characterised by energetically-costly fasting during incubation and frequent intermittent breeding, common eiders are ideal for studying the life-history trade-off between reproduction and survival. I relied on a longterm individual-based monitoring of breeding females (> 2500 breeding attempts from > 1000 individuals in 2008-2022) to explore variations in risktaking behaviour (measured by flight initiation distance) and physiological proxies of energy allocation (baseline corticosterone levels) and parental effort (baseline prolactin levels) in response to temporally and spatially variable predation risk. The longitudinal data collection was not restricted to the focal variables, but also integrated a monitoring of female characteristics (e.g., age, body condition and clutch size) and parameters such as nesting microhabitat and fine- and large-scale predation risk ...
|
|---|