Interacting effects of unobserved heterogeneity and individual stochasticity in the life history of the southern fulmar

• Published in: Journal of Animal Ecology
• Main Authors: Jenouvrier, Stéphanie, Aubry, Lise, Barbraud, Christophe, Weimerskirch, Henri, Caswell, Hal
• Other Authors: Woods Hole Oceanographic Institution (WHOI), Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Colorado State University Fort Collins (CSU), Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam Amsterdam (UvA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: frailty; individual quality; latent; life expectancy; lifetime reproductive success; [SDE]Environmental Sciences; Fulmar; Ile des Pétrels; Pétrels; Antarc*; Antarctica
• Online Access: https://hal.archives-ouvertes.fr/hal-02045560; https://doi.org/10.1111/1365-2656.12752

International audience 1. Individuals are heterogeneous in many ways. Some of these differences are incorporatedas individual states (e.g. age, size, breeding status) in population models.However, substantial amounts of heterogeneity may remain unaccounted for, dueto unmeasurable genetic, maternal or environmental factors.2. Such unobserved heterogeneity (UH) affects the behaviour of heterogeneous cohortsvia intra-cohort selection and contributes to inter-individual variance in demographicoutcomes such as longevity and lifetime reproduction. Variance is alsoproduced by individual stochasticity, due to random events in the life cycle of wildorganisms, yet no study thus far has attempted to decompose the variance in demographicoutcomes into contributions from UH and individual stochasticity for ananimal population in the wild.3. We developed a stage-classified matrix population model for the southern fulmarbreeding on Ile des Pétrels, Antarctica. We applied multievent, multistate mark–recapturemethods to estimate a finite mixture model accounting for UH in all vitalrates and Markov chain methods to calculate demographic outcomes. Finally, wepartitioned the variance in demographic outcomes into contributions from UH andindividual stochasticity.4. We identify three UH groups, differing substantially in longevity, lifetime reproductiveoutput, age at first reproduction and in the proportion of the life spent in eachreproductive state.– 14% of individuals at fledging have a delayed but high probability of recruitmentand extended reproductive life span.– 67% of individuals are less likely to reach adulthood, recruit late and skip breedingoften but have the highest adult survival rate.– 19% of individuals recruit early and attempt to breed often. They are likely to raisetheir offspring successfully, but experience a relatively short life span.Unobserved heterogeneity only explains a small fraction of the variances in longevity(5.9%), age at first reproduction (3.7%) and lifetime reproduction (22%).5. UH can affect the ...