The relationship between egg size and fertilization success in broadcast-spawning marine invertebrates.

Egg size is a critical life-history trait because it can profoundly influence offspring fitness and the number of offspring that can be produced. Recently, interest has grown in how egg size influences fertilization rate and in turn how sperm availability might influence the evolution of egg size among broadcast-spawning marine invertebrates. In this article I review the empirical evidence on the ways in which egg size and egg accessory structures influence fertilization and theoretical models of the ways sperm availability might influence the evolution of egg size. Evidence suggests that egg size does influence the collision frequency with sperm, and models suggest that sperm availability can influence selection on egg size. Sperm availability appears to be one of the several factors that influence optimal egg size in broadcast-spawning marine invertebrates.