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Using predator-prey theory to predict outcomes of a broad-scale test of apparent competition

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posted on 16.09.2020 by R Serrouya, M Wittmann, B McLellan, Heiko Wittmer, S Boutin
© 2015 by The University of Chicago. 0003-0147/2015/18505-55371$15.00. All rights reserved. Apparent competition is an important process influencing many ecological communities. We used predator-prey theory to predict outcomes of ecosystem experiments aimed at mitigating apparent competition by reducing primary prey. Simulations predicted declines in secondary prey following reductions in primary prey because predators consumed more secondary prey until predator numbers responded to reduced prey densities. Losses were exacerbated by a higher carrying capacity of primary prey and a longer lag time of the predator’s numerical response, but a gradual reduction in primary prey was less detrimental to the secondary prey. We compared predictions against two field experiments where endangered woodland caribou (Rangifer tarandus caribou) were victims of apparent competition. First, when deer (Odocoileus sp.) declined suddenly following a severe winter, cougar (Puma concolor) declined with a 1– 2-year lag, yet in the interim more caribou were killed by cougars, and caribou populations declined by 40%. Second, when moose (Alces alces) were gradually reduced using a management experiment, wolf (Canis lupus) populations declined but did not shift consumption to caribou, and the largest caribou subpopulation stabilized. The observed contrasting outcomes of sudden versus gradual declines in primary prey supported theoretical predictions. Combining theory with field studies clarified how to manage communities to mitigate endangerment caused by apparent competition that affects many taxa.

History

Preferred citation

Serrouya, R., Wittmann, M., McLellan, B., Wittmer, H. & Boutin, S. (2015). Using predator-prey theory to predict outcomes of a broad-scale test of apparent competition. The American Naturalist, 185(5), 665-679. https://doi.org/10.1086/680510

Journal title

The American Naturalist

Volume

185

Issue

5

Publication date

01/01/2015

Pagination

665-679

Publisher

University of Chicago Press

Publication status

Published

Contribution type

Article

ISSN

0003-0147

eISSN

1537-5323

Language

en

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