# Theory does not meet experiment: transient dynamics changes patterns of exclusion in an intraguild predation system

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## Abstract

Although empirical verifications of ecological theory are essential for the advance of our understanding of ecosystems functioning, they are often hard to obtain or even impractical. In this work we perform a detailed analysis of unexpected results found in a previous test of intraguild predation (IGP) theory. When the IG prey is the stronger competitor the IGP theory predicts a clear dynamical pattern along a resource gradient. In particular, the IG predator is expected to be excluded at low resources. In the experiment we analyze, IG prey was excluded at a resource level where the IG predator should be eliminated. We use a simple IGP model parametrized using mainly preliminary tests of the experiment. We suggest that experiment and theory agree if we look to the transient dynamics instead of asymptotic states, in which the usual theory is based. We show that extremely low IG prey populations during the transient may drive it to extinction and prevent the system from reaching long-term states. Our results are shown to be robust with respect to changes in initial conditions and parameters.

## Keywords

Community modules Population dynamics Test of ecological theory Transient exclusion## Notes

### Acknowledgements

The authors thank the Brazilian funding agencies CAPES, CNPq and FAPESP for financial support. We also thank André M. de Roos and Renato M. Coutinho for useful comments and suggestions on this work.

## References

- Amarasekare P (2010) Chap 2. Spatial dynamics of multitrophic communities. In: Cantrell S, Cosner C, Ruan S (eds) Spatial ecology. Chapman and Hall, Boca Raton, pp 15–31Google Scholar
- Arim M, Marquet PA (2004) Intraguild predation: a widespread interaction related to species biology. Ecol Lett 7:557–564CrossRefGoogle Scholar
- Borer ET, Briggs CJ, Murdoch WW, Swarbrick SL (2003) Testing intraguild predation theory in a field system: does numerical dominance shift along a gradient of productivity. Ecol Lett 6:929–935CrossRefGoogle Scholar
- Briggs CJ, Borer ET (2005) Why short-term experiments may not allow long-term predictions about intraguild predation. Ecol Appl 15(4):1111–1117CrossRefGoogle Scholar
- Diehl S, Feissel M (2001) Intraguild prey suffer from enrichment of their resources: a microcosm experiment with ciliates. Ecology 82(11):2977–2983CrossRefGoogle Scholar
- Hastings A (2001) Transient dynamics and persistence of ecological systems. Ecol Lett 4:215–220CrossRefGoogle Scholar
- Hastings A (2004) Transients: the key to long-term ecological understanding? Trends Ecol Evol 19(1):39–45CrossRefPubMedGoogle Scholar
- Hirsch MW, Smale S, Devaney RL (2013) Differential equations, dynamical systems, and an introduction to chaos, 3rd edn. Elsevier Academic Press, WalthamGoogle Scholar
- Montserrat M, Magalhes S, Sabelis MW, de Roos AM, Janssen A (2008) Patterns of exclusion in an intraguild predator–prey system depend on initial conditions. J Anim Ecol 77:624–630CrossRefPubMedGoogle Scholar
- Morin P (1999) Productivity, intraguild predation, and population dynamics in experimental food webs. Ecology 80(3):752–760CrossRefGoogle Scholar
- Mylius SD, Klumpers K, de Roos AM, Persson L (2001) Impact of intraguild predation and stage structure on simple communities along a productivity gradient. Am Nat 158(3):259–276CrossRefPubMedGoogle Scholar
- Noonburg EG, Abrams PA (2005) Transient dynamics limit the effectiveness of keystone predation in bringing about coexistence. Am Nat 165(3):322–335CrossRefPubMedGoogle Scholar
- Pimm SL, Lawton JH (1978) On feeding on more than one trophic level. Nature 275:542–544CrossRefGoogle Scholar
- Polis GA, Holt RD (1992) Intraguild predation: the dynamics of complex trophic interactions. Trends Ecol Evol 7:151–155CrossRefPubMedGoogle Scholar
- Polis GA, Holt RD (1997) A theoretical framework for intraguild predation. Am Nat 149(4):745–764CrossRefGoogle Scholar
- Polis GA, Holt RD, Myers CA (1989) The ecology and evolution of intraguild predation: potential competitors that eat each other. Annu Rev Ecol Syst 20:297–330CrossRefGoogle Scholar
- Rosenzweig ML (1971) Paradox of enrichment: destabilization of exploitation ecosystems in ecological time. Science 171:385–387CrossRefPubMedGoogle Scholar
- Rosenzweig ML, MacArthur RH (1963) Graphical representation and stability conditions of predator–prey interactions. Am Nat 97(895):209–223CrossRefGoogle Scholar
- Shulenburger L, Lai Y, Yalinkaya T, Holt RD (1999) Controlling transient chaos to prevent species extinction. Phys Lett A 260:156–161CrossRefGoogle Scholar
- Steiner CF, Klausmeier CA, Litchman E (2012) Transient dynamics and the destabilizing effects of prey heterogeneity. Ecology 93(3):632–644CrossRefPubMedGoogle Scholar
- Tilman D (1990) Mechanisms of plant competition for nutrients: the elements of a predictive theory of competition. In: Grace J, Tilman D (eds) Perspectives on plant competition. Academic Press, San Diego, pp 117–141Google Scholar
- van Rijn PCJ, van Houten YM, Sabelis MW (2002) How plants benefit from providing food to predators even when it is also edible to herbivores. Ecology 83(10):2664–2679CrossRefGoogle Scholar