The Ecology of Fertilization in Free-Spawning Invertebrates
This chapter addresses the likelihood of fertilization in the sea, the factors that can mediate fertilization success, and the ecological and evolutionary consequences of variation in fertilization success. Spawning behavior, the number and distribution of individuals, and flow conditions may dictate the local concentration of sperm and eggs, but understanding the transition between gamete concentration and fertilization success requires detailed study in the laboratory. Spawning is rarely witnessed, and when it is, appropriate data-collection equipment may not be readily available. Predicting fertilization success in the laboratory is fairly straightforward, as the relevant parameters are relatively easy to measure, but the highly complex water mass in which natural fertilization occurs can make even the most simple measurements, such as gamete concentration, difficult to obtain. Adult and offspring survivorship may also be influenced by behaviors associated with increased spawning success. Spawning individuals often place themselves in an exposed posture while releasing gametes, which might increase the risk of predation.