Age, size, and spatiotemporal variation in ovulation patterns of a seasonal breeder, the Norwegian moose (Alces alces).

• Published in: The American Naturalist
• Main Authors: Garel, M., Solberg, E.J., Sæther, B.-E., Grøtan, V., Tufto, J., Heim, M.
• Other Authors: Laboratoire de Biométrie et Biologie Evolutive - UMR 5558 (LBBE), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Recherche en Informatique et en Automatique (Inria)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Centre National de la Recherche Scientifique (CNRS), CCIN2P3
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2009
• Subjects: MESH: Aging; MESH: Animals; MESH: Seasons; MESH: Body Size; MESH: Deer; MESH: Female; MESH: Geography; MESH: Models; Biological; Statistical; MESH: Norway; MESH: Ovulation; [SDV.OT]Life Sciences [q-bio]/Other [q-bio.OT]; Norway; Alces alces
• Online Access: https://hal.archives-ouvertes.fr/hal-00428315; https://doi.org/10.1086/593359

In seasonal environments, timing of reproduction is an important fitness component. However, in ungulates, our understanding of this biological process is limited. Here we analyze how age and body mass affect spatiotemporal variation in timing of ovulation of 6,178 Norwegian moose. We introduced a parametric statistical model to obtain inferences about the seasonal timing of ovulation peak, the degree of synchrony among individuals, and the proportion of individuals that ovulate. These components showed much more spatiotemporal variation than previously reported. Young (primiparous) and old (> or =11.5 years of age) females ovulated later than prime-aged (2.5-10.5 years of age) females. In all age classes, ovulation was delayed with decreasing body mass. Ovulation rates were lower and more variable among primiparous females than among older females. Young females required higher body mass than older females did to ovulate. The body-mass-to-ovulation relationship varied with age, showed large regional variation, and differed among years within region. These results suggest that (1) environmental and population characteristics contribute to shape seasonal variation in the breeding pattern and (2) large regional variation exists in the size-dependent age at maturity in moose. Hence, the life-history trade-off between reproduction and body growth should differ regionally in moose.