Publication Date:
2022-05-26
Description:
Author Posting. © Ecological Society of America, 2019. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecology, (2019): e02874, doi: 10.1002/ecy.2874.
Description:
Resource competition theory predicts that when two species compete for a single, finite resource, the better competitor should exclude the other. However, in some cases, weaker competitors can persist through intraguild predation, that is, by eating their stronger competitor. Mixotrophs, species that meet their carbon demand by combining photosynthesis and phagotrophic heterotrophy, may function as intraguild predators when they consume the phototrophs with which they compete for light. Thus, theory predicts that mixotrophy may allow for coexistence of two species on a single limiting resource. We tested this prediction by developing a new mathematical model for a unicellular mixotroph and phytoplankter that compete for light, and comparing the model's predictions with a laboratory experimental system. We find that, like other intraguild predators, mixotrophs can persist when an ecosystem is sufficiently productive (i.e., the supply of the limiting resource, light, is relatively high), or when species interactions are strong (i.e., attack rates and conversion efficiencies are high). Both our mathematical and laboratory models show that, depending upon the environment and species traits, a variety of equilibrium outcomes, ranging from competitive exclusion to coexistence, are possible.
Description:
HVM and MGN designed the model. HVM and MDJ designed the experimental test system. HVM performed the model analysis, conducted the experiments, and analyzed the data. All authors wrote the paper. We thank Susanne Wilken for generously providing axenic CCMP 2951 and 1393 cultures for our use. R. Germain, S. Louca, G. Owens, N. Sharp, P. Thompson, and J. Yoder provided valuable feedback on figure design. We also thank J. Bronstein, S. Diehl, J. Huisman, C. Klausmeier, and four anonymous reviewers for comments on earlier versions of this manuscript. HVM was supported by a United States National Science Foundation Postdoctoral Research Fellowship in Biology (Grant DBI‐1401332) and a University of British Columbia Biodiversity Research Centre Postdoctoral Fellowship. This material is based upon work supported by the National Science Foundation under Grants OCE‐1655686 and OCE‐1436169, by a grant from the Simons Foundation/SFARI (561126, HMS), and by the Woods Hole Oceanographic Institution's Investment in Science Program. Research was also sponsored by the U.S. Army Research Office and was accomplished under Cooperative Agreement Number W911NF‐19‐2‐0026 for the Institute for Collaborative Biotechnologies.
Keywords:
community ecology
;
competition
;
Micromonas commoda
;
mixotrophy
;
model‐data comparison
;
Ochromonas
Repository Name:
Woods Hole Open Access Server
Type:
Article
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