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Codominance of two symbiont genera within the same coral host is associated with elevated symbiont productivity and lower host susceptibility to thermal stress
  • Evelyn Abbott,
  • Groves Dixon,
  • Mikhail Matz
Evelyn Abbott
University of Texas at Austin

Corresponding Author:[email protected]

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Groves Dixon
University of Texas
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Mikhail Matz
University of Texas at Austin
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As sea surface temperature increases, many coral species that used to harbor symbionts of the genus Cladocopium have become colonized with the thermally tolerant genus, Durusdinium. Here, we asked how symbionts of one genus react to the presence of another symbiont genus within the same coral host, and what effect this has on the host. We used previously published data from Acropora hyacinthus corals hosting Cladocopium and/or Durusdinium symbionts and looked at gene expression in all three symbiotic partners depending on the relative proportions of symbiont genera within the host. We find that both Cladocopium and Durusdinium change their expression most when their proportions are nearly equal (the state that we call “codominance”): both genera elevate expression of photosynthesis and ribosomal genes, suggesting increase in photosynthesis and growth (i.e. higher productivity). At the same time, the coral host also elevates production of ribosomes suggesting faster cellular growth, and, when heated, shows less pronounced stress response. These results can be explained in two ways. One explanation is that increased competition between symbionts heightens their productivity, which benefits the host, making it more resilient to stress. Alternatively, the symbionts’ elevated productivity might be the consequence of the host being particularly healthy. Under this explanation, rapid growth of the healthy host creates new space, lowering the symbionts’ competition and allowing for codominance. The latter explanation is supported by the fact that codominance is associated with lower symbiont densities. Irrespective of the causation, the presence of mixed symbiont communities could potentially be used as an instant indicator of coral well-being, which would be a useful tool for coral conservation and restoration.
20 Jan 2021Submitted to Molecular Ecology
23 Jan 2021Submission Checks Completed
23 Jan 2021Assigned to Editor
16 Feb 2021Review(s) Completed, Editorial Evaluation Pending
28 Feb 2021Reviewer(s) Assigned
23 Apr 2021Editorial Decision: Revise Minor
03 Jun 2021Review(s) Completed, Editorial Evaluation Pending
03 Jun 20211st Revision Received
10 Jun 2021Reviewer(s) Assigned
16 Aug 2021Editorial Decision: Revise Minor
23 Aug 2021Review(s) Completed, Editorial Evaluation Pending
23 Aug 20212nd Revision Received
10 Sep 2021Editorial Decision: Accept