Experimental evolution in coral photosymbionts as a tool to increase thermal tolerance

Chakravarti, Leela J., and van Oppen, Madeleine J.H. (2018) Experimental evolution in coral photosymbionts as a tool to increase thermal tolerance. Frontiers in Marine Science, 5. 227.

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Coral reefs are under major threat from ocean warming. When temperatures become too high corals bleach, expelling their symbiotic, photosynthetic microalgae (Symbiodinium), which they depend on for much of their nutritional requirements. Prolonged bleaching has led to widespread coral mortality and the severity and frequency of bleaching events are predicted to increase in the future. Coral bleaching tolerance is influenced by the thermal tolerance of the Symbiodinium harboured, and these microbial members of the coral holobiont may be able to evolve more rapidly than the coral host itself. Here, we examined the response of replicate cultures of five genetically distinct Symbiodinium strains (A3c, two types of D1, G3, and F1) to increasing temperatures over the course of approximately one year. For three Symbiodinium types (types A3c, G3, and F1), we observed a stable adaptive change at the end of this exposure period, which equated to only 41-69 asexual generations. The long-term selected Symbiodinium culture replicates (SS) showed faster growth rates under short-term, acute heat stress, and in some cases higher photosynthetic efficiencies, compared to wild-type populations (WT). Our results considerably extend the field of experimental evolution in Symbiodinium and with further work into the Symbiodinium-coral association and bleaching response, this approach may become a valuable tool in coral reef conservation and restoration initiatives.

Item ID: 58555
Item Type: Article (Research - C1)
ISSN: 2296-7745
Keywords: Acclimation, Adaptation, Assisted evolution, Climate change, Ocean warming, Symbiodinium, Symbiosis
Copyright Information: Copyright © 2018 Chakravarti and van Oppen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Funders: Paul G. Allen Family Foundation, Australian Institute of Marine Science, James Cook University Postgraduate Research Scholarship
Date Deposited: 10 Jun 2019 00:47
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310305 Marine and estuarine ecology (incl. marine ichthyology) @ 50%
41 ENVIRONMENTAL SCIENCES > 4101 Climate change impacts and adaptation > 410102 Ecological impacts of climate change and ecological adaptation @ 50%
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