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Genotypic similarity among algal symbionts corresponds to associations with closely related coral hosts

Reich, Hannah G. and Kitchen, Sheila A. and Stankiewicz, Kathryn H. and Devlin-Durante, Meghann and Fogarty, Nicole D. and Baums, Iliana B. (2020) Genotypic similarity among algal symbionts corresponds to associations with closely related coral hosts. . (Unpublished)

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Mutualisms where hosts are coupled metabolically to their symbionts often exhibit high partner fidelity. Most reef-building corals form obligate symbioses with specific species of photosymbionts, dinoflagellates in the family Symbiodiniaceae, despite needing to acquire symbionts early in their development from environmental sources. Three Caribbean acroporids (Acropora palmata, A. cervicornis, and their hybrid A. prolifera) are geographically sympatric across much of their range in the greater Caribbean, but often occupy different depth and light habitats. Both species and their hybrid associate with Symbiodinium 'fitti', a genetically diverse species of symbiont that is specific to these hosts. Since the physiology of the dinoflagellate partner is strongly influenced by light (and therefore depth), we investigated whether S. 'fitti' populations from each host source were differentiated genetically. We generated shallow genome sequences of acroporid colonies sampled from across the Caribbean. Single Nucleotide Polymorphisms (SNPs) among S. 'fitti' strains were identified by aligning sequences to a ~600 Mb draft assembly of the S. 'fitti' genome, assembled from an A. cervicornis metagenome. Phylogenomic and multivariate analyses revealed that allelic variation among S. 'fitti' partitioned to each host species, as well as their hybrid, rather than by biogeographic origin. This is particularly noteworthy because the hybrid, A. prolifera, has a sparse fossil record and may be of relatively recent origin. Many of the SNPs putatively under selection were non-synonymous mutations predicted to alter protein efficiency. Differences in allele frequency among S. 'fitti' populations from each host taxon may correspond to distinct phenotypes that thrive in the different cellular environments found in each acroporid. The non-random sorting among genetically diverse strains, or genotypes, to different hosts could be the basis for lineage diversification via disruptive selection, leading to ecological specialization and ultimately speciation.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Reich, Hannah G.0000-0002-8622-8801
Kitchen, Sheila A.0000-0003-4402-8139
Fogarty, Nicole D.0000-0003-3811-3791
Baums, Iliana B.0000-0001-6463-7308
Alternate Title:Allelic variation of an endangered coral symbiont
Additional Information:The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. Posted September 26, 2020. We thank the PSU genomics facility for assistance with library prep and sequencing. We thank Prof. Todd LaJeunesse for assistance with the psbA phylogeny. Funding for this project was supported by NSF-OCE-1537959 (to IBB) and NSF-OCE-1538469 (to NDF). HGR was supported through NSF-OCE-1636022 (to T. LaJeunesse). Permits for samples include Florida: CRF permit numbers CRF-2017-009, CRF-2017-012, NOAA FKNMS permit numbers FKNMS-2011-159-A4, FKNMS-2001-009, FKNMS-2014-148-A2, and FKNMS-2010-130-A, Belize: CITES Permit 0385, 7487 and 7488; Curacao: CITES Permit 16US784243/9 and 12US784243/9; and USVI Department of planning and natural resources, Division of fish and wildlife DFW14017T.
Funding AgencyGrant Number
Subject Keywords:Acropora, hybrid, niche diversification, single-nucleotide polymorphisms, Symbiodiniaceae, symbiosis
Record Number:CaltechAUTHORS:20200928-124858321
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Official Citation:Genotypic similarity among algal symbionts corresponds to associations with closely related coral hosts. Hannah G. Reich, Sheila A. Kitchen, Kathryn H. Stankiewicz, Meghann Devlin-Durante, Nicole D. Fogarty, Iliana B. Baums. bioRxiv 2020.09.26.314773; doi:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105585
Deposited By: Tony Diaz
Deposited On:28 Sep 2020 21:17
Last Modified:16 Nov 2021 18:44

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