Stability of an octocoral-algal symbiosis over time and space

• Published in: Marine ecology. Progress series (Halstenbek) 2003-03, Vol.250, p.117-124
• Main Authors: Goulet, Tamar L., Coffroth, Mary Alice
• Format: Article
• Language: English
• Subjects: Bacteriology; Biological and medical sciences; Bleaching; Coral reefs; Corals; DNA; DNA fingerprinting; Fundamental and applied biological sciences. Psychology; Genetics; Genetics of eukaryotes. Biological and molecular evolution; Genotypes; Habitats; Marine; Microbiology; Mutualism; Plexaura kuna; Population genetics, reproduction patterns; Symbionts; Symbiosis; Thallophyta, bryophyta; Vegetals
• ISSN: 0171-8630; 1616-1599
• DOI: 10.3354/meps250117

In symbiosis, 2 taxonomically different organisms co-exist, each pursuing their own agenda and yet, they are linked in one entity. A mutualistic symbiosis may break up if it is no longer beneficial to either one of the partners. Changing needs over time or changing environmental conditions may prompt symbiont switching. For example, corals may survive elevated temperatures by switching their algal symbionts. If switching occurs, the new combination of host and symbiont genotypes may perform better. Conversely, the partners may be fixed for life, with the degree to which the mutualism responds to changing selection pressures dictated by the existing partners. Understanding the genotypic dynamics of a mutualism is important for predicting the potential resilience of a mutualism over time and in the face of environmental perturbations. Although mutualisms tend to be characterized at the species level or higher, host-symbiont dynamics is an individual-level question, requiring individual-level analysis. We used multilocus DNA fingerprinting to examine long-term temporal and spatial symbiont change in the mutualism between the octocoralPlexaura kunaand its algal symbionts (zooxanthellae). We monitored zooxanthella genotypes within a colony for up to 10 yr, amongP. kunaclonemates, across different habitats and in colonies transplanted to novel environments. In all instances, the prominent zooxanthella genotype within aP. kunacolony remained unchanged although zooxanthella genotypes varied among genetically distinctP. kunacolonies. Such tremendous temporal and spatial stability may occur in other coral hosts, influencing the reaction and survival of mutualisms during environmental change.