CEES Extra seminar: When the going gets tough, the tough get going: effect of extreme climate on an Antarctic seabird life history
By Stéphanie Jenouvrier from Woods Hole Oceanographic Institution (USA) and Centre d’études Biologiques de Chizé (France)
Individuals differ in many ways, with most producing few or no offspring while a “tough'' few contribute disproportionately to the next generation. Extreme poor environmental conditions may exacerbate differences among individuals, such that when the going gets tough, only the “tough'’ get going. Some individual differences are observable but substantial unobserved heterogeneity (UH) often remains.
Accounting for UH revealed three groups of individuals with specific life histories within a population of an Antarctic seabird. These groups differ substantially in longevity, lifetime reproductive output, age at first reproduction, and in the proportion of the life spent in each reproductive state:
- 14% of individuals at edging have a delayed but high probability of recruitment and extended reproductive lifespan.
- 67% of individuals are less likely to reach adulthood, recruit late and skip breeding often but have the highest adult survival rate.
- 19% of individuals recruit early and attempt to breed often. They are likely to raise their offspring successfully, but experience a relatively short lifespan.
We found that these groups respond differently to extreme sea ice conditions (SICs) in their in vital rates, life history outcomes (LO) and fitness. The differences in these life history traits dramatically increase in extreme low sea ice conditions. Furthermore, we detected substantial variance in LO, which result from the combined effect of individual stochasticity (evolutionary neutral) and heterogeneity (potentially adaptive). There is an intense debate on the relative importance of these contributions and we found for the first time that the relative contributions of individual stochasticity and heterogeneity varied greatly across sea ice conditions.
Stéphanie Jenouvrier is an associate scientist at the Woods Hole Oceanographic Institution (USA) and Centre d’études Biologiques de Chizé (France). She is an ecologist interested in understanding and predicting the effect of climate change on life history and population dynamics, especially for seabirds in the Southern Ocean. Her work combines long-term longitudinal data with demographic, statistical and mathematical models coupled with climates models participating in the Intergovernmental Panel on climate change assessment.