Predicting invasive species impacts in a changing world

By Katy Ratcliffe

Based on a seminar given by Professor Jaimie Dick written in the style of a Letter to Nature summary paragraph.

In ecology, a functional response is defined as the intake rate of a consumer as a function of food density (7). The ecological process of predation involves several, basic components that underlie all further research (2). Analysing the complexity of predator-prey relationships requires models that provide conclusive findings (5) and have been previously tested (4). Here is shown how assessment of predatory functional responses plays important roles in predator-prey dynamics and how further interactions such as parasitism and higher-order predation, have the potential to modify predator–prey interactions and the ability to predict comparative functional responses (6). Experimentation found that invasive amphipods had a higher predatory impact than native amphipods. Parasitism was shown to influence predation and had the potential to both reduce the impact of the invasive species and increase the impact of the native species. Consumption of prey was similar for both predators and was associated with increasing prey densities (6) in context, this study further supports the application of comparative functional responses in order to predict and assess the impacts of invasive species (3). Continuing to determine the functional responses of predators throughout their life may further improve our understanding and prediction of their impacts in the community (1). The introduction of a more than two species dynamic can also provide a powerful tool when advancing our understanding of how predation and parasitism influence community composition (3).


1. Alexandera, M.E., Dick, J.T.A. & O’Connora, N.E. Born to kill: Predatory functional responses of the littoral amphipod Echinogammarus marinus Leach throughout its life history. Journal of Experimental Marine Biology and Ecology. 439, 92 – 99 (2013)

2. Cheng, T.C. Current Topics in Comparitive Pathobiology, Volume 2. Academic Press Incorporated, New York (1973)

3. Gange, A.C. & Brown, V.K. Multitrophic Interactions in Terrestrial Systems. Cambridge University Press, New York. (2009)

4. Holling, C.S. The Analysis of Complex Population Processes. The Canadian Entomologist. 96, 335-347 (1964)

5. Holling, C.S. The Functional Response of Predators to Prey Density and its Role in Mimicry and Population Regulation. Memoirs of the Entomological Society of Canada. 97, 5-60 (1965)

6. Paterson, R.A., Dick, J.T.A., Pritchard D.W., Ennis, M., Hatcher, M.J. & Dunn, A.M. Predicting invasive species impacts: a community module functional response approach reveals context dependencies. Journal of Animal Ecology. 84, 453-463 (2014)

7. Walley, G.S. Review of Edmund M. Walker. The Odonata of Canada and Alaska. The Canadian Entomologist. 91, 291-292 (1959)

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