Meeting Abstract

S4.6  Monday, Jan. 4  Bending corallines: biomechanical adaptations of segmented calcified seaweeds MARTONE, Patrick T.; University of British Columbia pmartone@interchange.ubc.ca

Flexibility is a critical characteristic of plants growing in unsteady flow. For example, leaves flutter in the wind and seaweeds ‘go with the flow’ to reduce drag. Given this paradigm of flexibility, I explore calcified coralline algae (Rhodophyta, Corallinaceae) which thrive in and dominate wave-exposed coastlines around the world. Many corallines produce flexible upright fronds by separating calcified segments with joints, called genicula. Such segmentation has evolved convergently in several lineages of hydrodynamically-stressed calcifying seaweeds and is thought to represent a common evolutionary trade-off decreasing herbivory susceptibility while increasing flexibility. In this study, I explore the consequences of segmentation on seaweed flexibility and the biomechanical adaptations of articulated coralline algae to facilitate bending. Using a numerical model, I evaluate the effects of genicular morphology and material properties on frond flexibility and demonstrate that several genicular features appear to be adaptations to hydrodynamic stress. In addition, I describe the adaptive significance of genicular material properties and cellular structure and explore the developmental and chemical underpinnings that likely contribute to their emergent mechanical properties. By exploring the biomechanics of genicula at a variety of scales, these studies erect an extensive framework for investigating the convergent evolution of joints in other segmented taxa.