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Facultative lifestyle drives diversity of coral algal symbionts.
- Source :
-
Trends in Ecology & Evolution . Mar2024, Vol. 39 Issue 3, p239-247. 9p. - Publication Year :
- 2024
-
Abstract
- The Symbiodiniaceae have been coral symbionts for over 200 million years, yet they retain a facultative lifestyle because both the symbiotic and free-living stages offer unique selective advantages that ensure persistence of the algal lineage. There exists a dynamic competition and interaction between the coral host and algal symbionts that ensures survival of both under fluctuating environmental conditions. If algal symbiont-derived redox stress does not explain coral host bleaching, then it is possible that either or both partners generate a chemical cue that precipitates algal expulsion independent of malfunctions in their electron transport chains. We propose the 'stepping-stone model' as an explanation for the long-term and successful association between coral animals and their facultative algal symbionts, which in a stepwise manner creates novel Symbiodiniaceae lineages worldwide. The photosynthetic symbionts of corals sustain biodiverse reefs in nutrient-poor, tropical waters. Recent genomic data illuminate the evolution of coral symbionts under genome size constraints and suggest that retention of the facultative lifestyle, widespread among these algae, confers a selective advantage when compared with a strict symbiotic existence. We posit that the coral symbiosis is analogous to a 'bioreactor' that selects winner genotypes and allows them to rise to high numbers in a sheltered habitat prior to release by the coral host. Our observations lead to a novel hypothesis, the 'stepping-stone model', which predicts that local adaptation under both the symbiotic and free-living stages, in a stepwise fashion, accelerates coral alga diversity and the origin of endemic strains and species. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 01695347
- Volume :
- 39
- Issue :
- 3
- Database :
- Academic Search Index
- Journal :
- Trends in Ecology & Evolution
- Publication Type :
- Academic Journal
- Accession number :
- 175772708
- Full Text :
- https://doi.org/10.1016/j.tree.2023.10.005