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Temperature variability interacts with mean temperature to influence the predictability of microbial phenotypes


Fu, F-X and Tschitschko, B and Hutchins, DA and Larsson, ME and Baker, KG and McInnes, A and Kahlke, T and Verma, A and Murray, SA and Doblin, MA, Temperature variability interacts with mean temperature to influence the predictability of microbial phenotypes, Global Change Biology, 28, (19) pp. 5741-5754. ISSN 1354-1013 (2022) [Refereed Article]

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Copyright Statement

2022. The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License, ( which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

DOI: doi:10.1111/gcb.16330


Despite their relatively high thermal optima (Topt), tropical taxa may be particularly vulnerable to a rising baseline and increased temperature variation because they live in relatively stable temperatures closer to their Topt. We examined how microbial eukaryotes with differing thermal histories responded to temperature fluctuations of different amplitudes (0 control, +-2, +-4Celsius degree) around mean temperatures below or above their Topt. Cosmopolitan dinoflagellates were selected based on their distinct thermal traits and included two species of the same genus (tropical and temperate Coolia spp.), and two strains of the same species maintained at different temperatures for >500 generations (tropical Amphidinium massartii control temperature and high temperature, CT and HT, respectively). There was a universal decline in population growth rate under temperature fluctuations, but strains with narrower thermal niche breadth (temperate Coolia and HT) showed ~10% greater reduction in growth. At suboptimal mean temperatures, cells in the cool phase of the fluctuation stopped dividing, fixed less carbon (C) and had enlarged cell volumes that scaled positively with elemental C, N, and P and C:Chlorophyll-a. However, at a supra-optimal mean temperature, fixed C was directed away from cell division and novel trait combinations developed, leading to greater phenotypic diversity. At the molecular level, heat-shock proteins, and chaperones, in addition to transcripts involving genome rearrangements, were upregulated in CT and HT during the warm phase of the supra-optimal fluctuation (30 +- 4Celsius degree), a stress response indicating protection. In contrast, the tropical Coolia species upregulated major energy pathways in the warm phase of its supra-optimal fluctuation (25 +- 4Celsius degree), indicating a broadscale shift in metabolism. Our results demonstrate divergent effects between taxa and that temporal variability in environmental conditions interacts with changes in the thermal mean to mediate microbial responses to global change, with implications for biogeochemical cycling.

Item Details

Item Type:Refereed Article
Keywords:climate impact, climate variability, dinoflagellate, primary productivity
Research Division:Biological Sciences
Research Group:Plant biology
Research Field:Phycology (incl. marine grasses)
Objective Division:Environmental Management
Objective Group:Coastal and estuarine systems and management
Objective Field:Assessment and management of coastal and estuarine ecosystems
UTAS Author:Baker, KG (Dr Kirralee Baker)
ID Code:152918
Year Published:2022
Deposited By:Oceans and Cryosphere
Deposited On:2022-08-26
Last Modified:2022-11-21
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