Prey body size mediates the predation risk associated with being "odd"

Morrell, Lesley J.; Downing, Beatrice; Rodgers, Gwendolen M.

Abstract

Despite selection pressures on prey animals to maintain phenotypically homogeneous groups, variation in phenotype within animal groups is commonly observed. Although many prey animals preferentially associate with size-matched individuals, a lack of preference or a preference for nonmatching group mates is also commonly observed. We suggest that the assortative response to predation risk may be mediated by body size because larger bodied prey may be at greater risk of predation than smaller bodied prey when in a mixed group due to their greater potential profitability. We test this idea by observing attacks by three-spine sticklebacks Gasterosteus aculeatus on mixed groups of large and small Daphnia magna prey. We find that smaller Daphnia are at greatest risk when they form the majority of the group, whereas larger Daphnia are at the greatest predation risk when they form the minority. Thus, we predict that both large and small prey should benefit by association with large prey, generating a potential conflict over group membership that may lead to the mixed phenotype groups we observe in nature.

Citation

Morrell, L. J., Downing, B., & Rodgers, G. M. (2015). Prey body size mediates the predation risk associated with being "odd". Behavioral ecology, 26(1), 242-246. https://doi.org/10.1093/beheco/aru185

• Journal Article Type: Article
• Acceptance Date: Sep 16, 2014
• Online Publication Date: Oct 17, 2014
• Publication Date: 2015
• Deposit Date: Mar 24, 2015
• Publicly Available Date: Mar 24, 2015
• Journal: Behavioral ecology
• Print ISSN: 1045-2249
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 26
• Issue: 1
• Pages: 242-246
• DOI: https://doi.org/10.1093/beheco/aru185
• Keywords: Assortment; Confusion effect; Group living; Oddity effect; Shoaling
• Public URL: https://hull-repository.worktribe.com/output/371989
• Publisher URL: http://beheco.oxfordjournals.org/content/26/1/242.full.pdf+html
• Additional Information: Author's accepted manuscript of article published in: Behavioral ecology, 2015, v.26, issue 1 at: http://beheco.oxfordjournals.org/content/26/1/242.full.pdf+html.
• Contract Date: Mar 24, 2015