Investigating Potential Trade-Offs Associated with Immunity and Reproduction in the Northern Star Coral, Astrangia Poculata
Date
2023-05
Authors
Villafranca, Natalie
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Abstract
Most living organisms face ubiquitous pathogenic threats, and have consequently evolved immune systems to protect against potential invaders. However, many components of the immune system are physiologically costly to maintain and engage, often drawing resources away from other organismal processes such as growth and reproduction. These trade-offs have been studied in a wide diversity of systems in order to better understand how organisms respond to competing needs and optimize fitness. Research on these topics in cnidarians, which include ecologically important organisms like hard corals, is critical for understanding future ecological dynamics in the face of rapid environmental change. Here, we characterize trade-offs between constitutive immunity and reproduction in the facultatively symbiotic coral Astrangia poculata. We hypothesized that trade-offs would exist between constitutive immunity and reproduction. Further, we expected that corals with higher symbiont density would have proportionally higher energetic budgets, and thus more energy to allocate towards immunity or reproduction. Male colonies underwent ex situ spawning and sperm output was quantified. We then tested for correlations between reproductive output and common metrics of coral immunity including melanin synthesis, antioxidant production, and antibacterial activity. Finally, we tested for correlations between lipid and carbohydrate levels (as a proxy for energetic budget) and immune phenotype activity. We found no significant associations between reproductive output and immunity phenotype activities, and no differences in energetic metrics between symbiotic states. However, we did find a significant positive association between melanin production and lipid and carbohydrate concentration. The lack of observed trade-offs highlights complexities in energetic budgets, the importance of characterizing multiple traits when considering these questions, and the potential nuances associated with laboratory-based approaches. Our results provide a preliminary framework for future studies to understand immune trade-offs in cnidarians which will further improve knowledge on how corals allocate resources in response to disease.
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Keywords
coral, trade-offs
Citation
Villafranca, N. (2023). Investigating potential trade-offs associated with immunity and reproduction in the northern star coral, Astrangia poculata (Unpublished thesis). Texas State University, San Marcos, Texas.