Oecologia

, Volume 162, Issue 3, pp 627–639

Observational evidence of risk-sensitive reproductive allocation in a long-lived mammal

  • Bård-Jørgen Bårdsen
  • Torkild Tveraa
  • Per Fauchald
  • Knut Langeland
Behavioral ecology - Original Paper

Abstract

Organisms should adopt a risk-sensitive reproductive allocation when summer reproductive allocation competes with survival in the coming winter. This trade off is shown through autumn female body mass, which acts as an insurance against unpredictable winter environmental conditions. We tested this hypothesis on female reindeer in a population that has experienced a time period of dramatic increase in abundance. Environmental conditions during winter were fairly stable (with the exception of 1 year). We conclude that increased population abundance (perhaps in interaction with winter environmental conditions) could have represented a worsening of winter environmental conditions as both autumn offspring and spring female body mass decreased during the course of the study. Moreover, we found that the cost of reproduction was related to environmental conditions as: (1) autumn body mass was larger for barren than for lactating females, and this difference was temporally highly variable; (2) lactating females produced smaller offspring than barren ones in the following year; and (3) reproductive output (offspring size) decreased over time. We also found evidence of quality effects as lactating females had a higher reproductive success in the following year. In sum, a worsening of winter conditions lead to: (1) decreased reproductive output; (2) lowered autumn body mass for lactating females; and (3) increased body mass for barren females. Since females reduce their reproductive allocation as winter conditions becomes more severe, we conclude that reindeer have adopted a risk-sensitive reproductive allocation.

Keywords

Density dependence Environmental stochasticity Life history Phenotypic plasticity Rangifer tarandus 

Supplementary material

442_2009_1537_MOESM1_ESM.pdf (95 kb)
Supplementary material 1 (PDF 95 kb)
442_2009_1537_MOESM2_ESM.pdf (92 kb)
Supplementary material 2 (PDF 92 kb)
442_2009_1537_MOESM3_ESM.pdf (87 kb)
Supplementary material 3 (PDF 87 kb)

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Bård-Jørgen Bårdsen
    • 1
    • 2
  • Torkild Tveraa
    • 1
  • Per Fauchald
    • 1
    • 2
  • Knut Langeland
    • 1
    • 2
  1. 1.Arctic Ecology DepartmentNorwegian Institute for Nature Research (NINA), Polar Environmental CentreTromsøNorway
  2. 2.Department of BiologyUniversity of Tromsø (UIT)TromsøNorway

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