Oecologia

, Volume 163, Issue 3, pp 625–636

Spatial heterogeneity and functional response: an experiment in microcosms with varying obstacle densities

  • Céline Hauzy
  • Thomas Tully
  • Thierry Spataro
  • Grégory Paul
  • Roger Arditi
Population ecology - Original Paper

DOI: 10.1007/s00442-010-1585-5

Cite this article as:
Hauzy, C., Tully, T., Spataro, T. et al. Oecologia (2010) 163: 625. doi:10.1007/s00442-010-1585-5

Abstract

Spatial heterogeneity of the environment has long been recognized as a major factor in ecological dynamics. Its role in predator–prey systems has been of particular interest, where it can affect interactions in two qualitatively different ways: by providing (1) refuges for the prey or (2) obstacles that interfere with the movements of both prey and predators. There have been relatively fewer studies of obstacles than refuges, especially studies on their effect on functional responses. By analogy with reaction–diffusion models for chemical systems in heterogeneous environments, we predict that obstacles are likely to reduce the encounter rate between individuals, leading to a lower attack rate (predator–prey encounters) and a lower interference rate (predator–predator encounters). Here, we test these predictions under controlled conditions using collembolans (springtails) as prey and mites as predators in microcosms. The effect of obstacle density on the functional response was investigated at the scales of individual behavior and of the population. As expected, we found that increasing obstacle density reduces the attack rate and predator interference. Our results show that obstacles, like refuges, can reduce the predation rate because obstacles decrease the attack rate. However, while refuges can increase predator dependence, we suggest that obstacles can decrease it by reducing the rate of encounters between predators. Because of their opposite effect on predator dependence, obstacles and refuges could modify in different ways the stability of predator–prey communities.

Keywords

Encounter rates Habitat complexity Mutual interference Predator–prey interaction 

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Céline Hauzy
    • 1
    • 3
    • 4
  • Thomas Tully
    • 1
    • 2
  • Thierry Spataro
    • 1
    • 3
  • Grégory Paul
    • 5
  • Roger Arditi
    • 1
    • 3
  1. 1.UMR7625 Écologie et ÉvolutionUniversité Pierre et Marie CurieParisFrance
  2. 2.IUFM de ParisUniversité Paris 4 - SorbonneParisFrance
  3. 3.USC2031-INRA Écologie des populations et communautésAgroParisTechParisFrance
  4. 4.IFM Theory and ModellingLinköping UniversityLinköpingSweden
  5. 5.Institute of Theoretical Computer Science and Swiss Institute of BioinformaticsETH ZürichZurichSwitzerland

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