Meeting Abstract

72.5  Monday, Jan. 6 09:00  Using gamete characteristics to model fertilization kinetics in latitudinal comparisons of fertilization success for sea urchins under variable temperature and pCO2 PODOLSKY, RD*; BENFIELD, C; DOOLEY, T; College of Charleston; Cornell University; College of Charleston podolskyr@cofc.edu

Populations evolving under different conditions may show regional adaptation to variation in environmental parameters that are predictable. Although latitudinal patterns of adaptation have been described in adult size, form, coloration, and physiology of several species, less is known about latitudinal adaptation of performance characteristics at early life-history stages. We examined differences in fertilization kinetics between northern and southern populations of the sea urchin Arbacia punctulata. Fertilization assays found that the proportion of eggs fertilized per sperm dilution factor was substantially higher in individuals from the northern population compared to the southern population under all combinations of temperature, pCO2, and sperm age tested. These results suggest that gametes from colder water populations demonstrate greater fertilization efficiency, consistent with expectations in biochemical adaptation under different temperature conditions. We measured and incorporated into a fertilization kinetics model population differences in sperm motility, sperm swimming speed, sperm density of spawn, and egg size to understand whether physical characteristics of gametes and their interactions could explain latitudinal differences in fertilization success. Our results will be presented in the context of the potential for responses of populations of free-spawning organisms to future changes in temperature and pH levels in the ocean.