Positive early-late life-history trait correlations in elephant seals

• Published in: Ecology
• Main Authors: Chris Oosthuizen, W., Péron, Guillaume, Pradel, Roger, Bester, Marthan, N., de Bruyn, Nico
• Other Authors: Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), Université Paul-Valéry - Montpellier 3 (UPVM)-École Pratique des Hautes Études (EPHE), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Sud )-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut Agro - Montpellier SupAgro, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: actuarial senescence; age at first reproduction; breeding age; imperfect detection; theory of ageing; hidden Markov model; life-history covariation; Mirounga leonina; [SDE]Environmental Sciences; Elephant Seals; Southern Elephant Seals
• Online Access: https://hal.science/hal-03021568; https://hal.science/hal-03021568/document; https://hal.science/hal-03021568/file/Oosthuizen%20Ecology%202020%20submitted.pdf; https://doi.org/10.1002/ecy.3288

International audience Correlations between early-and late-life performance are a major prediction of life-history theory. Negative early-late correlations can emerge because biological processes are optimized for early but not late life (e.g., rapid development may accelerate the onset of senescence; "developmental theory of ageing") or because allocation to early life performance comes at a cost in terms of late-life performance (as in the disposable soma theory). But, variation in genetic and environmental challenges that each individual has to cope with during early life may also lead to positive early-late life-history trait correlations (the "fixed heterogeneity" or "individual quality" hypothesis). We analyzed individual life-history trajectories of 7,420 known-age female southern elephant seals (Mirounga leonina) monitored over 36 years to determine how actuarial senescence (a proxy for late-life performance) correlate with age at first reproduction (a proxy for early-life performance). As some breeding events may not be detected in this field study, we used a custom "multievent" hierarchical model to estimate the age at first reproduction and correlate it to other life-history traits. The probability of first reproduction was 0.34 at age 3, with most females breeding for the first time at age 4, and comparatively few at older ages. Females with an early age of first reproduction outperformed delayed breeders in all aspects we considered (survival, rate of senescence, net reproductive output) but one: early breeders appeared to have an onset of actuarial senescence one year earlier compared to late breeders. Genetics and environmental conditions during early-life likely explain the positive correlation between early-and late-life performance. Our results provide the first evidence of actuarial senescence in female southern elephant seals.