Coverdale, TC, McGeary, IJ, O'Connell, RD et al. (6 more authors) (2019) Strong but opposing effects of associational resistance and susceptibility on defense phenotype in an African savanna plant. Oikos, 128 (12). pp. 1772-1782. ISSN 0030-1299
Abstract
The susceptibility of plants to herbivores can be strongly influenced by the identity, morphology and palatability of neighboring plants. While the defensive traits of neighbors often determine the mechanism and strength of associational resistance and susceptibility, the effect of neighbors on plant defense phenotype remains poorly understood. We used field surveys and a prickle-removal experiment in a semi-arid Kenyan savanna to evaluate the efficacy of physical defenses against large mammalian herbivores in a common understory plant, Solanum campylacanthum. We then quantified the respective effects of spinescent Acacia trees and short-statured grasses on browsing damage and prickle density in S. campylacanthum. We paired measurements of prickle density beneath and outside tree canopies with long-term herbivore-exclusion experiments to evaluate whether associational resistance reduced defense investment by decreasing browsing damage. Likewise, we compared defense phenotype within and outside pre-existing and experimentally created clearings to determine whether grass neighbors increased defense investment via associational susceptibility. Removing prickles increased the frequency of browsing by ~25%, and surveys of herbivory damage on defended leaves suggested that herbivores tended to avoid prickles. As predicted, associational resistance and susceptibility had opposing effects on plant phenotype: individuals growing beneath Acacia canopies (or, analogously, within large-herbivore exclosures) had a significantly lower proportion of their leaves browsed and produced ~ 70–80% fewer prickles than those outside refuges, whereas plants in grass-dominated clearings were more heavily browsed and produced nearly twice as many prickles as plants outside clearings. Our results demonstrate that associational resistance and susceptibility have strong, but opposing, effects on plant defense phenotype, and that variable herbivore damage is a major source of intraspecific variation in defense phenotype in this system.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2019 Nordic Society Oikos. This is an author produced version of a paper published in Oikos. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Associational effects; associational refuge; herbivory; physical plant defences; Solanum incanum; spines and thornes |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Biological Sciences (Leeds) > School of Biology (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 17 Sep 2019 10:33 |
Last Modified: | 18 Jul 2020 00:38 |
Status: | Published |
Publisher: | Nordic Ecological Society |
Identification Number: | 10.1111/oik.06644 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:150920 |