Model complexity affects transient population dynamics following a dispersal event: A case study with pea aphids

Brigitte Tenhumberg, Andrew J. Tyre, Richard Rebarber

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Stage-structured population models predict transient population dynamics if the population deviates from the stable stage distribution. Ecologists' interest in transient dynamics is growing because populations regularly deviate from the stable stage distribution, which can lead to transient dynamics that differ significantly from the stable stage dynamics. Because the structure of a population matrix (i.e., the number of life-history stages) can influence the predicted scale of the deviation, we explored the effect of matrix size on predicted transient dynamics and the resulting amplification of population size. First, we experimentally measured the transition rates between the different life-history stages and the adult fecundity and survival of the aphid, Acythosiphon pisum. Second, we used these data to parameterize models with different numbers of stages. Third, we compared model predictions with empirically measured transient population growth following the introduction of a single adult aphid. We find that the models with the largest number of life-history stages predicted the largest transient population growth rates, but in all models there was a considerable discrepancy between predicted and empirically measured transient peaks and a dramatic underestimation of final population sizes. For instance, the mean population size after 20 days was 2394 aphids compared to the highest predicted population size of 531 aphids; the predicted asymptotic growth rate (λmax) was consistent with the experiments. Possible explanations for this discrepancy are discussed.

Original languageEnglish (US)
Pages (from-to)1878-1890
Number of pages13
Issue number7
StatePublished - Jul 2009


  • Acythosiphon pisum
  • Aphids
  • Life-history stages
  • Matrix population models
  • Population dynamics
  • Transient amplification

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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