Caught in the middle: Asymmetric competition causes high variance in intermediate trait abundances

Edwin van Leeuwen*, Rampal S. Etienne

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

7 Citations (Scopus)

Abstract

In asymmetric competition between two individuals of the same or different species, one individual has a distinct advantage over the other due to a particular beneficial trait. An important trait that induces asymmetric competition is size (body size in animals, height in plants). There is usually a trade-off between fecundity and the trait that leads to competitive superiority (e.g. seed number vs seed size), enabling coexistence of populations with different trait values. These predictions on coexistence are based on classic deterministic models. Here, we explore the behaviour of a stochastic model of asymmetric competition where stochasticity is assumed to be demographic. We derive approximations for the temporal variance and covariance of the population sizes of the coexisting species. The derivations highlight that the variability of the population size of a species strongly depends on the stochastic fluctuations of species with higher trait values, while they are less influenced by species with lower trait values. Particularly, species with intermediate trait values are strongly affected resulting in relatively high variability. As a result these species have a relative high probability of extinction even though they have a larger population size than species with high trait values. We confirm these approximations with individual-based simulations. Thus, our analysis can explain gaps in size distributions as an emergent property of systems with a fecundity-competition trade-off. (c) 2013 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)26-37
Number of pages12
JournalTheoretical Population Biology
Volume85
DOIs
Publication statusPublished - May-2013

Keywords

  • Asymmetric competition
  • Temporal variance
  • Evolution
  • Plant height
  • Stochasticity
  • Adaptive dynamics
  • BODY-SIZE
  • EVOLUTIONARY GAME
  • INTERSPECIFIC COMPETITION
  • LIMITING SIMILARITY
  • FIELD EXPERIMENTS
  • RED DEER
  • POPULATIONS
  • VARIABILITY
  • DYNAMICS
  • STOCHASTICITY

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