Reproductive success in large populations: empirical measures and theoretical predictions of fertilization in the sea biscuit Clypeaster rosaceus

For organisms that free-spawn gametes into the environment, sperm limitation can be a major determinant of reproductive success. Previous tests of sperm limitation have been restricted to very small experimental populations. Here we test and then use a fertilization model to explore sperm limitation in large populations. Predictions of the fertilization model are compared with measures of dye diffusion and in situ fertilization of the sea biscuit Clypeaster rosaceus (Linnaeus). The model could not be rejected in either test. Then this model was used to simulate large-scale spawning events in a natural population of C. rosaceus.