Villafranca, N. | bioRxiv Science

bioRxiv2025

Morphological plasticity in a reef-building coral is context-dependent and trades off with resistance to thermal stress

In sessile, long-lived organisms, such as reef-building corals, phenotypic plasticity may play a key role in mitigating the impacts of climate change. Plasticity is often context-dependent and has costs and limits, ultimately resulting in adaptive, neutral, or maladaptive effects. However, our understanding of the mechanisms that maintain variation in, and therefore drive the evolution of, plasticity is still limited. We use a field-based transplant experiment to show context-dependent tradeoffs to morphological plasticity in Acropora cervicornis under real-world conditions driven by climate change. We find that while morphological plasticity is neutral under some conditions, it trades off with thermal tolerance during moderate temperature stress during a marine heatwave. Additionally, we find that plasticity changes over time, underlining the importance of its temporal dynamics in long-lived organisms. Our results demonstrate a key role for environmental change in the eco-evolutionary dynamics of plasticity by demonstrating context-dependent costs under real-world thermal stress.

evolutionary biology↗

bioRxiv2023

Characterization of trade-offs between immunity and reproduction in Astrangia poculata

BackgroundLiving 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. Evidence from a diversity of systems has demonstrated that organisms use complex resource allocation mechanisms to manage competing needs and optimize fitness. However, understanding of resource allocation patterns is limited across taxa. Cnidarians, which include ecologically important organisms like hard corals, have been historically understudied in the context of resource allocations. Improving understanding of resource allocation-associated tradeoffs in cnidarians is critical for understanding future ecological dynamics in the face of rapid environmental change. MethodsHere, we characterize trade-offs between constitutive immunity and reproduction in the facultatively symbiotic coral Astrangia poculata. Male colonies underwent ex situ spawning and sperm output was quantified. We then examined the effects of variable symbiont density and energetic budget on physiological traits, including immune activity and reproductive investment. Furthermore, we tested for potential trade-offs between immune activity and reproductive investment. ResultsWe found limited effects of energetic budget on immune metrics; melanin production was significantly positively associated with energetic budget. However, we failed to document any associations between immunity and reproductive output which would be indicative of trade-offs, possibly due to experimental limitations. Our results provide a preliminary framework for future studies investigating immune trade-offs in cnidarians.

immunology↗