Henri Weimerskirch

Publications (5)91.66 Total impact

• Source

  Available from: Owen R Jones

  Article: Senescence rates are determined by ranking on the fast-slow life-history continuum.

  Owen R Jones, Jean-Michel Gaillard, Shripad Tuljapurkar, Jussi S Alho, Kenneth B Armitage, Peter H Becker, Pierre Bize, Jon Brommer, Anne Charmantier, Marie Charpentier, [......], Hannu Pietiäinen, Thor Harald Ringsby, Alexandre Roulin, Bernt-Erik Saether, Joanna M Setchell, Ben C Sheldon, Paul M Thompson, Henri Weimerskirch, E Jean Wickings, Tim Coulson
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  ABSTRACT: Comparative analyses of survival senescence by using life tables have identified generalizations including the observation that mammals senesce faster than similar-sized birds. These generalizations have been challenged because of limitations of life-table approaches and the growing appreciation that senescence is more than an increasing probability of death. Without using life tables, we examine senescence rates in annual individual fitness using 20 individual-based data sets of terrestrial vertebrates with contrasting life histories and body size. We find that senescence is widespread in the wild and equally likely to occur in survival and reproduction. Additionally, mammals senesce faster than birds because they have a faster life history for a given body size. By allowing us to disentangle the effects of two major fitness components our methods allow an assessment of the robustness of the prevalent life-table approach. Focusing on one aspect of life history - survival or recruitment - can provide reliable information on overall senescence.
  Ecology Letters 08/2008; 11(7):664-73. · 17.56 Impact Factor
• Source

  Available from: Res Altwegg

  Article: Generation time and temporal scaling of bird population dynamics.

  Bernt-Erik Saether, Russell Lande, Steinar Engen, Henri Weimerskirch, Magnar Lillegård, Res Altwegg, Peter H Becker, Thomas Bregnballe, Jon E Brommer, Robin H McCleery, Juha Merilä, Erik Nyholm, Wallace Rendell, Raleigh R Robertson, Piotr Tryjanowski, Marcel E Visser
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  ABSTRACT: Theoretical studies have shown that variation in density regulation strongly influences population dynamics, yet our understanding of factors influencing the strength of density dependence in natural populations still is limited. Consequently, few general hypotheses have been advanced to explain the large differences between species in the magnitude of population fluctuations. One reason for this is that the detection of density regulation in population time series is complicated by time lags induced by the life history of species that make it difficult to separate the relative contributions of intrinsic and extrinsic factors to the population dynamics. Here we use population time series for 23 bird species to estimate parameters of a stochastic density-dependent age-structured model. We show that both the strength of total density dependence in the life history and the magnitude of environmental stochasticity, including transient fluctuations in age structure, increase with generation time. These results indicate that the relationships between demographic and life-history traits in birds translate into distinct population dynamical patterns that are apparent only on a scale of generations.
  Nature 08/2005; 436(7047):99-102. · 36.28 Impact Factor
• Article: Generation time and temporal scaling of bird population dynamics

  Bernt-Erik S|[aelig]|ther, Russell Lande, Steinar Engen, Henri Weimerskirch, Magnar Lilleg|[aring]|rd, Res Altwegg, Peter H. Becker, Thomas Bregnballe, Jon E. Brommer, Robin H. McCleery, Juha Meril|[auml, Erik Nyholm, Wallace Rendell, Raleigh R. Robertson, Piotr Tryjanowski, Marcel E. Visser
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  ABSTRACT: Theoretical studies have shown that variation in density regulation strongly influences population dynamics
  Nature 07/2005; 436(7047):99-102. · 36.28 Impact Factor
• Source

  Available from: math.ntnu.no

  Article: Extinction in relation to demographic and environmental stochasticity in age-structured models.

  Steinar Engen, Russell Lande, Bernt-Erik aether, Henri Weimerskirch
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  ABSTRACT: The demographic variance of an age-structured population is defined. This parameter is further split into components generated by demographic stochasticity in each vital rate. The applicability of these parameters are investigated by checking how an age-structured population process can be approximated by a diffusion with only three parameters. These are the deterministic growth rate computed from the expected projection matrix and the environmental and demographic variances. We also consider age-structured populations where the fecundity at any stage is either zero or one, and there is neither environmental stochasticity nor dependence between individual fecundity and survival. In this case the demographic variance is uniquely determined by the vital rates defining the projection matrix. The demographic variance for a long-lived bird species, the wandering albatross in the southwestern part of the Indian Ocean, is estimated. We also compute estimates of the age-specific contributions to the total demographic variance from survival, fecundity and the covariance between survival and fecundity.
  Mathematical Biosciences 07/2005; 195(2):210-27. · 1.54 Impact Factor
• Source

  Available from: János Török

  Article: Life-history variation predicts the effects of demographic stochasticity on avian population dynamics

  Bernt-Erik Saether, Steinar Engen, Anders Pape Møller, Henri Weimerskirch, Marcel E Visser, Wolfgang Fiedler, Erik Matthysen, Marcel M Lambrechts, Alexander Badyaev, Peter H Becker, [......], Frederick R Gehlbach, Dik Heg, Hermann Hötker, Juha Merilä, Jan Tøttrup Nielsen, Wallace Rendell, Raleigh J Robertson, David L Thomson, János Török, Piet Van Hecke
  Hastings Natural History Reservation. 13(93924).