1
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Wuitchik DM, Aichelman HE, Atherton KF, Brown CM, Chen X, DiRoberts L, Pelose GE, Tramonte CA, Davies SW. Photosymbiosis reduces the environmental stress response under a heat challenge in a facultatively symbiotic coral. Sci Rep 2024; 14:15484. [PMID: 38969663 PMCID: PMC11226616 DOI: 10.1038/s41598-024-66057-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 06/26/2024] [Indexed: 07/07/2024] Open
Abstract
The symbiosis between corals and dinoflagellates of the family Symbiodiniaceae is sensitive to environmental stress. The oxidative bleaching hypothesis posits that extreme temperatures lead to accumulation of photobiont-derived reactive oxygen species ROS, which exacerbates the coral environmental stress response (ESR). To understand how photosymbiosis modulates coral ESRs, these responses must be explored in hosts in and out of symbiosis. We leveraged the facultatively symbiotic coral Astrangia poculata, which offers an opportunity to uncouple the ESR across its two symbiotic phenotypes (brown, white). Colonies of both symbiotic phenotypes were exposed to three temperature treatments for 15 days: (i) control (static 18 °C), (ii) heat challenge (increasing from 18 to 30 °C), and (iii) cold challenge (decreasing from 18 to 4 °C) after which host gene expression was profiled. Cold challenged corals elicited widespread differential expression, however, there were no differences between symbiotic phenotypes. In contrast, brown colonies exhibited greater gene expression plasticity under heat challenge, including enrichment of cell cycle pathways involved in controlling photobiont growth. While this plasticity was greater, the genes driving this plasticity were not associated with an amplified environmental stress response (ESR) and instead showed patterns of a dampened ESR under heat challenge. This provides nuance to the oxidative bleaching hypothesis and suggests that, at least during the early onset of bleaching, photobionts reduce the host's ESR under elevated temperatures in A. poculata.
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Affiliation(s)
- D M Wuitchik
- Department of Biology, Boston University, Boston, MA, USA.
- Department of Biology, Tufts University, Medford, MA, USA.
| | - H E Aichelman
- Department of Biology, Boston University, Boston, MA, USA
| | - K F Atherton
- Department of Biology, Boston University, Boston, MA, USA
- Bioinformatics Graduate Program, Boston University, Boston, MA, USA
| | - C M Brown
- Department of Biology, Boston University, Boston, MA, USA
| | - X Chen
- Department of Biology, Boston University, Boston, MA, USA
| | - L DiRoberts
- Department of Biology, Boston University, Boston, MA, USA
| | - G E Pelose
- Department of Biology, Boston University, Boston, MA, USA
| | - C A Tramonte
- Department of Biology, Boston College, Boston, MA, USA
| | - S W Davies
- Department of Biology, Boston University, Boston, MA, USA.
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2
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Strader ME, Wright RM, Pezner AK, Nuttall MF, Aichelman HE, Davies SW. Intersection of coral molecular responses to a localized mortality event and ex situ deoxygenation. Ecol Evol 2024; 14:e11275. [PMID: 38654712 PMCID: PMC11036075 DOI: 10.1002/ece3.11275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 03/22/2024] [Accepted: 04/01/2024] [Indexed: 04/26/2024] Open
Abstract
In July 2016, East Bank of Flower Garden Banks (FGB) National Marine Sanctuary experienced a localized mortality event (LME) of multiple invertebrate species that ultimately led to reductions in coral cover. Abiotic data taken directly after the event suggested that acute deoxygenation contributed to the mortality. Despite the large impact of this event on the coral community, there was no direct evidence that this LME was driven by acute deoxygenation, and thus we explored whether gene expression responses of corals to the LME would indicate what abiotic factors may have contributed to the LME. Gene expression of affected and unaffected corals sampled during the mortality event revealed evidence of the physiological consequences of the LME on coral hosts and their algal symbionts from two congeneric species (Orbicella franksi and Orbicella faveolata). Affected colonies of both species differentially regulated genes involved in mitochondrial regulation and oxidative stress. To further test the hypothesis that deoxygenation led to the LME, we measured coral host and algal symbiont gene expression in response to ex situ experimental deoxygenation (control = 6.9 ± 0.08 mg L-1, anoxic = 0.083 ± 0.017 mg L-1) in healthy O. faveolata colonies from the FGB. However, this deoxygenation experiment revealed divergent gene expression patterns compared to the corals sampled during the LME and was more similar to a generalized coral environmental stress response. It is therefore likely that while the LME was connected to low oxygen, it was a series of interconnected stressors that elicited the unique gene expression responses observed here. These in situ and ex situ data highlight how field responses to stressors are unique from those in controlled laboratory conditions, and that the complexities of deoxygenation events in the field likely arise from interactions between multiple environmental factors simultaneously.
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Affiliation(s)
- Marie E. Strader
- Department of BiologyTexas A&M UniversityCollege StationTexasUSA
| | - Rachel M. Wright
- Department of Biological SciencesSouthern Methodist UniversityDallasTexasUSA
| | | | | | | | - Sarah W. Davies
- Department of BiologyBoston UniversityBostonMassachusettsUSA
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3
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Connelly MT, Snyder G, Palacio-Castro AM, Gillette PR, Baker AC, Traylor-Knowles N. Antibiotics reduce Pocillopora coral-associated bacteria diversity, decrease holobiont oxygen consumption and activate immune gene expression. Mol Ecol 2023; 32:4677-4694. [PMID: 37317893 DOI: 10.1111/mec.17049] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 05/22/2023] [Accepted: 05/31/2023] [Indexed: 06/16/2023]
Abstract
Corals are important models for understanding invertebrate host-microbe interactions; however, to fully discern mechanisms involved in these relationships, experimental approaches for manipulating coral-bacteria associations are needed. Coral-associated bacteria affect holobiont health via nutrient cycling, metabolic exchanges and pathogen exclusion, yet it is not fully understood how bacterial community shifts affect holobiont health and physiology. In this study, a combination of antibiotics (ampicillin, streptomycin and ciprofloxacin) was used to disrupt the bacterial communities of 14 colonies of the reef framework-building corals Pocillopora meandrina and P. verrucosa, originally collected from Panama and hosting diverse algal symbionts (family Symbiodiniaceae). Symbiodiniaceae photochemical efficiencies and holobiont oxygen consumption (as proxies for coral health) were measured throughout a 5-day exposure. Antibiotics altered bacterial community composition and reduced alpha and beta diversity, however, several bacteria persisted, leading to the hypothesis that these bacteria are either antibiotics resistant or occupy internal niches that are shielded from antibiotics. While antibiotics did not affect Symbiodiniaceae photochemical efficiency, antibiotics-treated corals had lower oxygen consumption rates. RNAseq revealed that antibiotics increased expression of Pocillopora immunity and stress response genes at the expense of cellular maintenance and metabolism functions. Together, these results reveal that antibiotic disruption of corals' native bacteria negatively impacts holobiont health by decreasing oxygen consumption and activating host immunity without directly impairing Symbiodiniaceae photosynthesis, underscoring the critical role of coral-associated bacteria in holobiont health. They also provide a baseline for future experiments that manipulate Pocillopora corals' symbioses by first reducing the diversity and complexity of coral-associated bacteria.
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Affiliation(s)
- Michael T Connelly
- Department of Marine Biology and Ecology, University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science, Miami, Florida, USA
| | - Grace Snyder
- Department of Marine Biology and Ecology, University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science, Miami, Florida, USA
| | - Ana M Palacio-Castro
- University of Miami Cooperative Institute for Marine and Atmospheric Studies, Miami, Florida, USA
- Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration, Miami, Florida, USA
| | - Phillip R Gillette
- Department of Marine Biology and Ecology, University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science, Miami, Florida, USA
| | - Andrew C Baker
- Department of Marine Biology and Ecology, University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science, Miami, Florida, USA
| | - Nikki Traylor-Knowles
- Department of Marine Biology and Ecology, University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science, Miami, Florida, USA
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4
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Haydon TD, Matthews JL, Seymour JR, Raina JB, Seymour JE, Chartrand K, Camp EF, Suggett DJ. Metabolomic signatures of corals thriving across extreme reef habitats reveal strategies of heat stress tolerance. Proc Biol Sci 2023; 290:20221877. [PMID: 36750192 PMCID: PMC9904954 DOI: 10.1098/rspb.2022.1877] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 01/11/2023] [Indexed: 02/09/2023] Open
Abstract
Anthropogenic stressors continue to escalate worldwide, driving unprecedented declines in reef environmental conditions and coral health. One approach to better understand how corals can function in the future is to examine coral populations that thrive within present day naturally extreme habitats. We applied untargeted metabolomics (gas chromatography-mass spectrometry (GC-MS)) to contrast metabolite profiles of Pocillopora acuta colonies from hot, acidic and deoxygenated mangrove environments versus those from adjacent reefs. Under ambient temperatures, P. acuta predominantly associated with endosymbionts of the genera Cladocopium (reef) or Durusdinium (mangrove), exhibiting elevated metabolism in mangrove through energy-generating and biosynthesis pathways compared to reef populations. Under transient heat stress, P. acuta endosymbiont associations were unchanged. Reef corals bleached and exhibited extensive shifts in symbiont metabolic profiles (whereas host metabolite profiles were unchanged). By contrast, mangrove populations did not bleach and solely the host metabolite profiles were altered, including cellular responses in inter-partner signalling, antioxidant capacity and energy storage. Thus mangrove P. acuta populations resist periodically high-temperature exposure via association with thermally tolerant endosymbionts coupled with host metabolic plasticity. Our findings highlight specific metabolites that may be biomarkers of heat tolerance, providing novel insight into adaptive coral resilience to elevated temperatures.
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Affiliation(s)
- Trent D. Haydon
- Center for Genomics and Systems Biology, New York University Abu Dhabi, PO Box 129188, Abu Dhabi, UAE
- Faculty of Science, Climate Change Cluster, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| | - Jennifer L. Matthews
- Faculty of Science, Climate Change Cluster, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| | - Justin R. Seymour
- Faculty of Science, Climate Change Cluster, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| | - Jean-Baptiste Raina
- Faculty of Science, Climate Change Cluster, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| | - Jamie E. Seymour
- Division of Tropical Health and Medicine, Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, QLD 4811, Australia
| | - Kathryn Chartrand
- Centre for tropical Water and Aquatic Ecosystem Research, James Cook University, Cairns, QLD 4811, Australia
| | - Emma F. Camp
- Faculty of Science, Climate Change Cluster, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| | - David J. Suggett
- Faculty of Science, Climate Change Cluster, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
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5
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Al-Hammady MA, Silva TF, Hussein HN, Saxena G, Modolo LV, Belasy MB, Westphal H, Farag MA. How do algae endosymbionts mediate for their coral host fitness under heat stress? A comprehensive mechanistic overview. ALGAL RES 2022. [DOI: 10.1016/j.algal.2022.102850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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6
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Rodriguez-Casariego JA, Cunning R, Baker AC, Eirin-Lopez JM. Symbiont shuffling induces differential DNA methylation responses to thermal stress in the coral Montastraea cavernosa. Mol Ecol 2021; 31:588-602. [PMID: 34689363 DOI: 10.1111/mec.16246] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 10/17/2021] [Accepted: 10/19/2021] [Indexed: 12/11/2022]
Abstract
Algal symbiont shuffling in favour of more thermotolerant species has been shown to enhance coral resistance to heat-stress. Yet, the mechanistic underpinnings and long-term implications of these changes are poorly understood. This work studied the modifications in coral DNA methylation, an epigenetic mechanism involved in coral acclimatization, in response to symbiont manipulation and subsequent heat stress exposure. Symbiont composition was manipulated in the great star coral Montastraea cavernosa through controlled thermal bleaching and recovery, producing paired ramets of three genets dominated by either their native symbionts (genus Cladocopium) or the thermotolerant species (Durusdinium trenchi). Single-base genome-wide analyses showed significant modifications in DNA methylation concentrated in intergenic regions, introns and transposable elements. Remarkably, DNA methylation changes in response to heat stress were dependent on the dominant symbiont, with twice as many differentially methylated regions found in heat-stressed corals hosting different symbionts (Cladocopium vs. D. trenchii) compared to all other comparisons. Interestingly, while differential gene body methylation was not correlated with gene expression, an enrichment in differentially methylated regions was evident in repetitive genome regions. Overall, these results suggest that changes in algal symbionts favouring heat tolerant associations are accompanied by changes in DNA methylation in the coral host. The implications of these results for coral adaptation, along with future avenues of research based on current knowledge gaps, are discussed in the present work.
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Affiliation(s)
- Javier A Rodriguez-Casariego
- Environmental Epigenetics Laboratory, Institute of Environment, Florida International University, Miami, Florida, USA
| | - Ross Cunning
- Daniel P. Haerther Center for Conservation and Research, John G. Shedd Aquarium, Chicago, Illinois, USA.,Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida, USA
| | - Andrew C Baker
- Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida, USA
| | - Jose M Eirin-Lopez
- Environmental Epigenetics Laboratory, Institute of Environment, Florida International University, Miami, Florida, USA
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7
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Abbott E, Dixon G, Matz M. Shuffling between Cladocopium and Durusdinium extensively modifies the physiology of each symbiont without stressing the coral host. Mol Ecol 2021; 30:6585-6595. [PMID: 34551161 DOI: 10.1111/mec.16190] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 08/23/2021] [Accepted: 09/10/2021] [Indexed: 12/28/2022]
Abstract
As sea surface temperatures increase, many coral species that used to harbour symbionts of the genus Cladocopium have become colonized with the thermally tolerant genus, Durusdinium. Here, we asked how gene expression in the symbionts of one genus changes depending on the abundance of another symbiont genus within the same coral host, and what effect this interaction has on the host. Symbiont gene expression was overwhelmingly driven by whether the genus was the minority or the majority within the host, which affected 79% (Durusdinium) and 96% (Cladocopium) of all genes. Particularly strong effects in both genera were observed for photosynthesis components (upregulated in the minority state) and proteins putatively associated with cell motility (upregulated in the majority state). Importantly, there was no distinct gene expression signature associated with the mixed symbiosis state when both genera were represented in comparable proportions within the host, which could lead to more intense competition. The mixed symbiosis was also not associated with elevated host stress: in fact, after heat treatment, stress signatures were the lowest in mixed-symbiosis corals compared to both Cladocopium- and Durusdinium-dominated corals. In conclusion, during shuffling between Cladocopium and Durusdinium both symbiont genera go through extensive and largely reciprocal physiological transitions, but there is no evidence of intensifying antagonistic interactions that are detrimental to the host. Unless the mixed-symbiosis corals in this study are not representative of the typical transition between Cladocopium and Durusdinium, the process of shuffling from one symbiont genus to another appears to be cost-free for the coral host, and even appears to be associated with lower stress susceptibility. This raises optimism for the future corals, which will probably have to rely on symbiont shuffling more and more to withstand environmental challenges.
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Affiliation(s)
- Evelyn Abbott
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA
| | - Groves Dixon
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA
| | - Mikhail Matz
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA
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8
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Rivera HE, Aichelman HE, Fifer JE, Kriefall NG, Wuitchik DM, Wuitchik SJS, Davies SW. A framework for understanding gene expression plasticity and its influence on stress tolerance. Mol Ecol 2021; 30:1381-1397. [PMID: 33503298 DOI: 10.1111/mec.15820] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 12/10/2020] [Accepted: 01/20/2021] [Indexed: 12/18/2022]
Abstract
Phenotypic plasticity can serve as a stepping stone towards adaptation. Recently, studies have shown that gene expression contributes to emergent stress responses such as thermal tolerance, with tolerant and susceptible populations showing distinct transcriptional profiles. However, given the dynamic nature of gene expression, interpreting transcriptomic results in a way that elucidates the functional connection between gene expression and the observed stress response is challenging. Here, we present a conceptual framework to guide interpretation of gene expression reaction norms in the context of stress tolerance. We consider the evolutionary and adaptive potential of gene expression reaction norms and discuss the influence of sampling timing, transcriptomic resilience, as well as complexities related to life history when interpreting gene expression dynamics and how these patterns relate to host tolerance. We highlight corals as a case study to demonstrate the value of this framework for non-model systems. As species face rapidly changing environmental conditions, modulating gene expression can serve as a mechanistic link from genetic and cellular processes to the physiological responses that allow organisms to thrive under novel conditions. Interpreting how or whether a species can employ gene expression plasticity to ensure short-term survival will be critical for understanding the global impacts of climate change across diverse taxa.
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Affiliation(s)
- Hanny E Rivera
- Department of Biology, Boston University, Boston, MA, USA
| | | | - James E Fifer
- Department of Biology, Boston University, Boston, MA, USA
| | | | | | - Sara J S Wuitchik
- Department of Biology, Boston University, Boston, MA, USA.,FAS Informatics, Harvard University, Cambridge, MA, USA
| | - Sarah W Davies
- Department of Biology, Boston University, Boston, MA, USA
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9
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Chan WY, Chung J, Peplow LM, Hoffmann AA, van Oppen MJH. Maternal effects in gene expression of interspecific coral hybrids. Mol Ecol 2020; 30:517-527. [PMID: 33179328 DOI: 10.1111/mec.15727] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 11/03/2020] [Accepted: 11/04/2020] [Indexed: 12/24/2022]
Abstract
Maternal effects have been well documented for offspring morphology and life history traits in plants and terrestrial animals, yet little is known about maternal effects in corals. Further, few studies have explored maternal effects in gene expression. In a previous study, F1 interspecific hybrid and purebred larvae of the coral species Acropora tenuis and Acropora loripes were settled and exposed to ambient or elevated temperature and pCO2 conditions for 7 months. At this stage, the hybrid coral recruits from both ocean conditions exhibited strong maternal effects in several fitness traits. We conducted RNA-sequencing on these corals and showed that gene expression of the hybrid Acropora also exhibited clear maternal effects. Only 40 genes were differentially expressed between hybrids and their maternal progenitor. In contrast, ~2000 differentially expressed genes were observed between hybrids and their paternal progenitors, and between the reciprocal F1 hybrids. These results indicate that maternal effects in coral gene expression can be long-lasting. Unlike findings from most short-term stress experiments in corals, no genes were differentially expressed in the hybrid nor purebred offspring after seven months of exposure to elevated temperature and pCO2 conditions.
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Affiliation(s)
- Wing Yan Chan
- Australian Institute of Marine Science, Townsville, QLD, Australia.,School of BioSciences, University of Melbourne, Parkville, VIC, Australia
| | - Jessica Chung
- Bio21 Institute, University of Melbourne, Parkville, VIC, Australia.,Melbourne Bioinformatics, University of Melbourne, Parkville, VIC, Australia
| | - Lesa M Peplow
- Australian Institute of Marine Science, Townsville, QLD, Australia
| | - Ary A Hoffmann
- Bio21 Institute, University of Melbourne, Parkville, VIC, Australia
| | - Madeleine J H van Oppen
- Australian Institute of Marine Science, Townsville, QLD, Australia.,School of BioSciences, University of Melbourne, Parkville, VIC, Australia
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10
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Davies SW, Moreland KN, Wham DC, Kanke MR, Matz MV. Cladocopium community divergence in two Acropora coral hosts across multiple spatial scales. Mol Ecol 2020; 29:4559-4572. [PMID: 33002237 DOI: 10.1111/mec.15668] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 09/14/2020] [Accepted: 09/18/2020] [Indexed: 12/11/2022]
Abstract
Many broadly-dispersing corals acquire their algal symbionts (Symbiodiniaceae) "horizontally" from their environment upon recruitment. Horizontal transmission could promote coral fitness across diverse environments provided that corals can associate with divergent algae across their range and that these symbionts exhibit reduced dispersal potential. Here we quantified community divergence of Cladocopium algal symbionts in two coral host species (Acropora hyacinthus, Acropora digitifera) across two spatial scales (reefs on the same island, and between islands) across the Micronesian archipelago using microsatellites. We find that both hosts associated with a variety of multilocus genotypes (MLG) within two genetically distinct Cladocopium lineages (C40, C21), confirming that Acropora coral hosts associate with a range of Cladocopium symbionts across this region. Both C40 and C21 included multiple asexual lineages bearing identical MLGs, many of which spanned host species, reef sites within islands, and even different islands. Both C40 and C21 exhibited moderate host specialization and divergence across islands. In addition, within every island, algal symbiont communities were significantly clustered by both host species and reef site, highlighting that coral-associated Cladocopium communities are structured across small spatial scales and within hosts on the same reef. This is in stark contrast to their coral hosts, which never exhibited significant genetic divergence between reefs on the same island. These results support the view that horizontal transmission could improve local fitness for broadly dispersing Acropora coral species.
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Affiliation(s)
- Sarah W Davies
- Department of Biology, Boston University, Boston, MA, USA.,Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
| | - Kelsey N Moreland
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
| | - Drew C Wham
- Department of Biology, Pennsylvania State University, University Park, PA, USA
| | - Matt R Kanke
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
| | - Mikhail V Matz
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
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11
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van Oppen MJH, Medina M. Coral evolutionary responses to microbial symbioses. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190591. [PMID: 32772672 PMCID: PMC7435167 DOI: 10.1098/rstb.2019.0591] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/09/2020] [Indexed: 12/19/2022] Open
Abstract
This review explores how microbial symbioses may have influenced and continue to influence the evolution of reef-building corals (Cnidaria; Scleractinia). The coral holobiont comprises a diverse microbiome including dinoflagellate algae (Dinophyceae; Symbiodiniaceae), bacteria, archaea, fungi and viruses, but here we focus on the Symbiodiniaceae as knowledge of the impact of other microbial symbionts on coral evolution is scant. Symbiosis with Symbiodiniaceae has extended the coral's metabolic capacity through metabolic handoffs and horizontal gene transfer (HGT) and has contributed to the ecological success of these iconic organisms. It necessitated the prior existence or the evolution of a series of adaptations of the host to attract and select the right symbionts, to provide them with a suitable environment and to remove disfunctional symbionts. Signatures of microbial symbiosis in the coral genome include HGT from Symbiodiniaceae and bacteria, gene family expansions, and a broad repertoire of oxidative stress response and innate immunity genes. Symbiosis with Symbiodiniaceae has permitted corals to occupy oligotrophic waters as the algae provide most corals with the majority of their nutrition. However, the coral-Symbiodiniaceae symbiosis is sensitive to climate warming, which disrupts this intimate relationship, causing coral bleaching, mortality and a worldwide decline of coral reefs. This article is part of the theme issue 'The role of the microbiome in host evolution'.
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Affiliation(s)
- Madeleine J. H. van Oppen
- School of BioSciences, The University of Melbourne, Parkville, 3010 Victoria, Australia
- Australian Institute of Marine Science, PMB No. 3, Townsville MC, 4810 Queensland, Australia
| | - Mónica Medina
- Department of Biology, The Pennsylvania State University, 208 Mueller Lab, University Park, PA 16802, USA
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12
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Cunning R, Baker AC. Thermotolerant coral symbionts modulate heat stress‐responsive genes in their hosts. Mol Ecol 2020; 29:2940-2950. [DOI: 10.1111/mec.15526] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 06/05/2020] [Accepted: 06/15/2020] [Indexed: 12/15/2022]
Affiliation(s)
- Ross Cunning
- Department of Marine Biology and Ecology Rosenstiel School of Marine and Atmospheric Science University of Miami Miami FL USA
- Daniel P. Haerther Center for Conservation and Research John G. Shedd Aquarium Chicago IL USA
| | - Andrew C. Baker
- Department of Marine Biology and Ecology Rosenstiel School of Marine and Atmospheric Science University of Miami Miami FL USA
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13
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Studivan MS, Voss JD. Transcriptomic plasticity of mesophotic corals among natural populations and transplants of
Montastraea cavernosa
in the Gulf of Mexico and Belize. Mol Ecol 2020; 29:2399-2415. [DOI: 10.1111/mec.15495] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 05/14/2020] [Accepted: 05/28/2020] [Indexed: 02/06/2023]
Affiliation(s)
- Michael S. Studivan
- Harbor Branch Oceanographic Institute Florida Atlantic University Fort Pierce FL USA
- Cooperative Institute for Marine and Atmospheric Studies University of Miami Rosenstiel School of Marine and Atmospheric Sciences Miami FL USA
| | - Joshua D. Voss
- Harbor Branch Oceanographic Institute Florida Atlantic University Fort Pierce FL USA
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14
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Buerger P, Alvarez-Roa C, Coppin CW, Pearce SL, Chakravarti LJ, Oakeshott JG, Edwards OR, van Oppen MJH. Heat-evolved microalgal symbionts increase coral bleaching tolerance. SCIENCE ADVANCES 2020; 6:eaba2498. [PMID: 32426508 PMCID: PMC7220355 DOI: 10.1126/sciadv.aba2498] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Accepted: 03/06/2020] [Indexed: 05/19/2023]
Abstract
Coral reefs worldwide are suffering mass mortalities from marine heat waves. With the aim of enhancing coral bleaching tolerance, we evolved 10 clonal strains of a common coral microalgal endosymbiont at elevated temperatures (31°C) for 4 years in the laboratory. All 10 heat-evolved strains had expanded their thermal tolerance in vitro following laboratory evolution. After reintroduction into coral host larvae, 3 of the 10 heat-evolved endosymbionts also increased the holobionts' bleaching tolerance. Although lower levels of secreted reactive oxygen species (ROS) accompanied thermal tolerance of the heat-evolved algae, reduced ROS secretion alone did not predict thermal tolerance in symbiosis. The more tolerant symbiosis exhibited additional higher constitutive expression of algal carbon fixation genes and coral heat tolerance genes. These findings demonstrate that coral stock with enhanced climate resilience can be developed through ex hospite laboratory evolution of their microalgal endosymbionts.
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Affiliation(s)
- P. Buerger
- CSIRO Synthetic Biology Future Science Platform, Land & Water, Black Mountain, ACT 2601, Australia
- School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia
| | - C. Alvarez-Roa
- Australian Institute of Marine Science, PMB #3, Townsville, QLD 4810, Australia
| | - C. W. Coppin
- CSIRO Synthetic Biology Future Science Platform, Land & Water, Black Mountain, ACT 2601, Australia
| | - S. L. Pearce
- CSIRO Synthetic Biology Future Science Platform, Land & Water, Black Mountain, ACT 2601, Australia
| | - L. J. Chakravarti
- Australian Institute of Marine Science, PMB #3, Townsville, QLD 4810, Australia
| | - J. G. Oakeshott
- CSIRO Synthetic Biology Future Science Platform, Land & Water, Black Mountain, ACT 2601, Australia
| | - O. R. Edwards
- CSIRO Synthetic Biology Future Science Platform, Land & Water, Black Mountain, ACT 2601, Australia
| | - M. J. H. van Oppen
- School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia
- Australian Institute of Marine Science, PMB #3, Townsville, QLD 4810, Australia
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15
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Wright RM, Mera H, Kenkel CD, Nayfa M, Bay LK, Matz MV. Positive genetic associations among fitness traits support evolvability of a reef-building coral under multiple stressors. GLOBAL CHANGE BIOLOGY 2019; 25:3294-3304. [PMID: 31301206 DOI: 10.1111/gcb.14764] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/09/2019] [Accepted: 06/19/2019] [Indexed: 05/20/2023]
Abstract
Climate change threatens organisms in a variety of interactive ways that requires simultaneous adaptation of multiple traits. Predicting evolutionary responses requires an understanding of the potential for interactions among stressors and the genetic variance and covariance among fitness-related traits that may reinforce or constrain an adaptive response. Here we investigate the capacity of Acropora millepora, a reef-building coral, to adapt to multiple environmental stressors: rising sea surface temperature, ocean acidification, and increased prevalence of infectious diseases. We measured growth rates (weight gain), coral color (a proxy for Symbiodiniaceae density), and survival, in addition to nine physiological indicators of coral and algal health in 40 coral genets exposed to each of these three stressors singly and combined. Individual stressors resulted in predicted responses (e.g., corals developed lesions after bacterial challenge and bleached under thermal stress). However, corals did not suffer substantially more when all three stressors were combined. Nor were trade-offs observed between tolerances to different stressors; instead, individuals performing well under one stressor also tended to perform well under every other stressor. An analysis of genetic correlations between traits revealed positive covariances, suggesting that selection to multiple stressors will reinforce rather than constrain the simultaneous evolution of traits related to holobiont health (e.g., weight gain and algal density). These findings support the potential for rapid coral adaptation under climate change and emphasize the importance of accounting for corals' adaptive capacity when predicting the future of coral reefs.
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Affiliation(s)
- Rachel M Wright
- Department of Biological Sciences, Smith College, Northampton, MA, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
| | - Hanaka Mera
- Australian Institute of Marine Science, Townsville, Qld, Australia
| | - Carly D Kenkel
- Australian Institute of Marine Science, Townsville, Qld, Australia
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Maria Nayfa
- Centre for Sustainable Tropical Fisheries and Aquaculture, College of Science and Engineering, James Cook University, Townsville, Qld, Australia
| | - Line K Bay
- Australian Institute of Marine Science, Townsville, Qld, Australia
| | - Mikhail V Matz
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, USA
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16
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Adapting to extreme environments: can coral reefs adapt to climate change? Emerg Top Life Sci 2019; 3:183-195. [DOI: 10.1042/etls20180088] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 02/23/2019] [Accepted: 03/11/2019] [Indexed: 12/15/2022]
Abstract
Abstract
Reef-building corals throughout the world have an annual value of tens of billions of dollars, yet they are being degraded at an increasing rate by many anthropogenic and environmental factors. Despite this, some reefs show resilience to such extreme environmental changes. This review shows how techniques in computational modelling, genetics, and transcriptomics are being used to unravel the complexity of coral reef ecosystems, to try and understand if they can adapt to new and extreme environments. Considering the ambitious climate targets of the Paris Agreement to limit global warming to 2°C, with aspirations of even 1.5°C, questions arise on how to achieve this. Geoengineering may be necessary if other avenues fail, although global governance issues need to play a key role. Development of large and effective coral refugia and marine protected areas is necessary if we are not to lose this vital resource for us all.
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17
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Helmkampf M, Bellinger MR, Frazier M, Takabayashi M. Symbiont type and environmental factors affect transcriptome-wide gene expression in the coral Montipora capitata. Ecol Evol 2019; 9:378-392. [PMID: 30680121 PMCID: PMC6341978 DOI: 10.1002/ece3.4756] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 11/01/2018] [Accepted: 11/02/2018] [Indexed: 12/18/2022] Open
Abstract
Reef-building corals may harbor genetically distinct lineages of endosymbiotic dinoflagellates in the genus Symbiodinium, which have been shown to affect important colony properties, including growth rates and resilience against environmental stress. However, the molecular processes underlying these differences are not well understood. In this study, we used whole transcriptome sequencing (RNA-seq) to assess gene expression differences between 27 samples of the coral Montipora capitata predominantly hosting two different Symbiodinium types in clades C and D. The samples were further characterized by their origin from two field sites on Hawai'i Island with contrasting environmental conditions. We found that transcriptome-wide gene expression profiles clearly separated by field site first, and symbiont clade second. With 273 differentially expressed genes (DEGs, 1.3% of all host transcripts), symbiont clade had a measurable effect on host gene expression, but the effect of field site proved almost an order of magnitude higher (1,957 DEGs, 9.6%). According to SNP analysis, we found moderate evidence for host genetic differentiation between field sites (F ST = 0.046) and among corals harboring alternative symbiont clades (F ST = 0.036), suggesting that site-related gene expression differences are likely due to a combination of local adaptation and acclimatization to environmental factors. The correlation between host gene expression and symbiont clade may be due to several factors, including host genotype or microhabitat selecting for alternative clades, host physiology responding to different symbionts, or direct modulation of host gene expression by Symbiodinium. However, the magnitude of these effects at the level of transcription was unexpectedly small considering the contribution of symbiont type to holobiont phenotype.
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Affiliation(s)
- Martin Helmkampf
- Tropical Conservation Biology and Environmental ScienceUniversity of Hawaiʻi at HiloHiloHawaii
| | - M. Renee Bellinger
- Tropical Conservation Biology and Environmental ScienceUniversity of Hawaiʻi at HiloHiloHawaii
| | - Monika Frazier
- Tropical Conservation Biology and Environmental ScienceUniversity of Hawaiʻi at HiloHiloHawaii
| | - Misaki Takabayashi
- Tropical Conservation Biology and Environmental ScienceUniversity of Hawaiʻi at HiloHiloHawaii
- Okinawa Institute of Science and TechnologyOnna-son, OkinawaJapan
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