Department of Ecology and Evolutionary Biology, University of California, 321 Steinhaus Hall, Irvine, CA 92697, USA.
Coastal Science and Policy Program, University of California Santa Cruz, 115 McAllister Way, Santa Cruz, CA 95060, USA.
Proc Biol Sci. 2020 Dec 9;287(1940):20201860. doi: 10.1098/rspb.2020.1860.
Mutualistic symbioses are common, especially in nutrient-poor environments where an association between hosts and symbionts can allow the symbiotic partners to persist and collectively out-compete non-symbiotic species. Usually these mutualisms are built on an intimate transfer of energy and nutrients (e.g. carbon and nitrogen) between host and symbiont. However, resource availability is not consistent, and the benefit of the symbiotic association can depend on the availability of resources to mutualists. We manipulated the diets of two temperate sea anemone species in the genus in the field and recorded the responses of sea anemones and algal symbionts in the family Symbiodiniaceae to our treatments. Algal symbiont density, symbiont volume and photosynthetic efficiency of symbionts responded to changes in sea anemone diet, but the responses depended on the species of sea anemone. We suggest that temperate sea anemones and their symbionts can respond to changes in anemone diet, modifying the balance between heterotrophy and autotrophy in the symbiosis. Our data support the hypothesis that symbionts are upregulated or downregulated based on food availability, allowing for a flexible nutritional strategy based on external resources.
互利共生关系很常见，特别是在营养贫瘠的环境中，宿主和共生体之间的联系可以使共生伙伴得以生存，并共同竞争非共生物种。通常情况下，这些共生关系是基于宿主和共生体之间的能量和营养物质（如碳和氮）的密切转移建立的。然而，资源的可用性并不一致，共生关系的好处可能取决于共生体对资源的可用性。我们在野外操纵了两个温带海葵属物种的饮食，并记录了海葵和共生藻家族 Symbiodiniaceae 对我们处理的反应。藻类共生体密度、共生体体积和共生体的光合作用效率对海葵饮食的变化有反应，但反应取决于海葵的种类。我们认为，温带海葵及其共生体可以对海葵饮食的变化做出反应，从而改变共生关系中异养和自养之间的平衡。我们的数据支持这样一种假设，即共生体根据食物的可利用性被上调或下调，从而允许基于外部资源的灵活营养策略。
