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Presentation Title: Consequences of calcification for coralline algal ecology and evolution Dr. Patrick Martone is a professor in the Botany Department at the University of British Columbia. Research in his lab spans a wide range of phycological topics, encompassing the biodiversity, biomechanics, ecophysiology, and evolution of seaweeds. Dr. Martone thinks carefully about the functional morphology of seaweeds and the evolutionary innovations that permit seaweeds to survive along wave-swept rocky shores. His work on seaweed biomechanics considers not only the movement of thalli in flow, but the structural and chemical nature of seaweed materials to resist breakage. He uses phylogenetic and taxonomic methods to explore the morphological diversification of seaweeds through time, and he is well known for his research on the evolutionary gains and losses of flexible joints in segmented calcified algae. His work on seaweed biodiversity has inspired renewed efforts to characterize and monitor hundreds of seaweed species along the Pacific coast of Canada and to better anticipate the physiological and ecological impacts of changing ocean conditions on seaweed communities. |
Presentation title: Consequences of calcification for coralline algal ecology and evolution
Calcification is a defining characteristic of coralline red algae that has likely impacted their ecology and the trajectory of their evolution for millions of years. Yet, the exact influence of calcification on ecological and evolutionary processes is fraught with assumptions, especially as adaptive landscapes may have shifted over time. For example, coralline have repeatedly overcome the biomechanical challenge of a calcified thallus and the resulting limitation on vertical growth by evolving flexible joints (genicula), giving rise to species with upright articulated fronds. However, some erect coralline thalli have weakened or restricted calcification, resembling fleshy seaweeds, and still persist alongside their calcified relatives. Moreover, recent work has identified crust species that evolved from articulated ancestors, representing evolutionary reversals that raise questions about the adaptive significance of upright growth entirely. Ecologically, calcified thalli are generally resistant to herbivory, but the exact mechanism of protection remains unclear. Serial decalcification of several coralline species had no significant effect on urchin or isopod grazing rates: fully calcified thalli were eaten as much as fully decalcified thalli. In only one coralline-grazer interaction did we document an increase in herbivory after decalcification, suggesting that protection provided by calcification is not generalizable and may be interaction-specific. Moreover, we found that the caloric value of a standardized volume (or “mouthful”) of coralline algae is similar to – and sometimes greater than – that of kelp, undermining past claims of caloric differences. As coralline research expands, we should revisit our basic assumptions about the past and present impact of calcification on coralline ecology and evolution.