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Title: Downstream resource leakage a necessary condition for the stress-gradient hypothesis in processing chain commensalisms
Authors: Sim, Hong Jhun
Lam, Weng Ngai
Chisholm, Ryan A.
Chong, Kwek Yan
Keywords: Science::Biological sciences
Issue Date: 2022
Source: Sim, H. J., Lam, W. N., Chisholm, R. A. & Chong, K. Y. (2022). Downstream resource leakage a necessary condition for the stress-gradient hypothesis in processing chain commensalisms. Journal of Theoretical Biology, 538, 111043-.
Journal: Journal of Theoretical Biology
Abstract: The stress-gradient hypothesis (SGH) in ecology predicts that the strength and frequency of positive interspecific interactions, including processing chain commensalisms (PCCs), increase with environmental stress. Although observed in some empirical PCC studies, a recent theoretical study of PCCs using a consumer-resource-type model found that, given the model's assumptions, the SGH never occurs. To investigate if this is a true reflection of PCCs or merely an artefact of the model, in this study, we modified this earlier model formulation by incorporating generalized, monotonically increasing resource uptake functions in place of linear functions, and added a term to represent the spontaneous leakage of the downstream resource to the environment. Mathematical analyses of the model revealed two key insights: 1) the specific algebraic forms of the functional responses of the species in a PCC do not affect the long-term behaviour of the system; 2) the SGH can occur in a facilitative interaction only if the consumer-independent leakage rate of the downstream resource exceeds the consumer-independent input rate. The first insight shows that the outcomes of consumer-resource interactions are robust to details of the functional responses when the functional responses are monotonically increasing, while the second insight shows that the SGH is not a universal feature of positive interactions but instead holds only under a well-defined set of conditions which may vary between PCC interactions and the environmental contexts in which they take place.
ISSN: 0022-5193
DOI: 10.1016/j.jtbi.2022.111043
Schools: Asian School of the Environment 
Organisations: National University of Singapore
Rights: © 2022 Elsevier Ltd. All rights reserved.
Fulltext Permission: none
Fulltext Availability: No Fulltext
Appears in Collections:ASE Journal Articles

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