title: Age-specific cost of first reproduction in female southern elephant seals.
abstract: When to commence breeding is a crucial life-history decision that may be the most important determinant of an individual's lifetime reproductive output and can have major consequences on population dynamics. The age at which individuals first reproduce is an important factor influencing the intensity of potential costs (e.g. reduced survival) involved in the first breeding event. However, quantifying age-related variation in the cost of first reproduction in wild animals remains challenging because of the difficulty in reliably recording the first breeding event. Here, using a multi-event capture-recapture model that accounts for both imperfect detection and uncertainty in the breeding status on an 18-year dataset involving 6637 individuals, we estimated age and state-specific survival of female elephant seals (Mirounga leonina) in the declining Macquarie Island population. We detected a clear cost of first reproduction on survival. This cost was higher for both younger first-time breeders and older first-time breeders compared with females recruiting at age four, the overall mean age at first reproduction. Neither earlier primiparity nor delaying primiparity appear to confer any evolutionary advantage, rather the optimal strategy seems to be to start breeding at a single age, 4 years.
authors.affiliation: Marine Predator Research Group, Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia marine.desprez@mq.edu.au.
authors.forename: Marine
authors.initials: M
authors.lastname: Desprez
authors.affiliation: Marine Predator Research Group, Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia.
authors.forename: Robert
authors.initials: R
authors.lastname: Harcourt
authors.affiliation: Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania 7001, Australia.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Hindell
authors.affiliation: Department of Zoology, University of Oxford, The Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Cubaynes
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive, Campus CNRS, UMR 5175, 1919 Route de Mende, 34293 Montpellier Cedex 5, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Gimenez
authors.affiliation: Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania 7001, Australia Sydney Institute of Marine Science, 19 Chowder Bay Road, Mosman, New South Wales 2088, Australia.
authors.forename: Clive R
authors.initials: CR
authors.lastname: McMahon
mesh_terms: D000367:Age Factors; D000818:Animals; D005260:Female; D009026:Mortality; D012098:Reproduction / Q000502:physiology*; D046048:Seals, Earless / Q000502:physiology*
keywords: Mirounga leonina; capture–mark–recapture; demography; life history; primiparity; survival