Meeting Abstract

107.6  Sunday, Jan. 6  Survival of the weakest: Decreased frond mechanical strength increases survival in a wave-swept kept via self-pruning DEMES, KW*; PRUITT, JN; HARLEY, CDG; CARRINGTON, E; University of British Columbia; University of Pittsburgh; University of British Columbia; University of Washington, Friday Harbor Labs demes@zoology.ubc.ca

Organisms’ ability to withstand the physical forces of their environment is a key determinant of their success. Mechanical performance of organisms is often dictated by the properties of the tissues which compose them. In mechanically stressful habitats, intraspecific variation in tissue properties may result in differential fitness and enable natural selection to act on material performance. We tested the hypothesis that tissue mechanical properties influence survivorship (a fitness component) of the perennial kelp, Egregia menziesii, in a mechanically stressful, wave-swept intertidal habitat. We measured intraspecific variation in frond strength and flexibility in 38 E. menziesii and tracked their survivorship in the field over the winter storm season to determine if variation in mechanical properties led to differential survivorship. Significant inter-individual variation was found in most mechanical properties, including strength and flexibility. Individuals with increased flexibility and decreased strength were more likely to survive the duration of our study, although this effect was more pronounced in individuals with smaller holdfasts. Increased frond strength was also associated with a reduction in self-thinning, potentially explaining the observed increase in whole plant mortality with increasing frond strength. Results from this study demonstrate that variation in tissue mechanical properties among conspecifics can influence survivorship and this has important evolutionary implications.