In the sea, do sperm from different males directly compete for eggs, and do eggs have a choice??

Do Sperm Really Compete and Do Eggs Ever Have a Choice? Adult Distribution and Gamete Mixing Influence Sexual Selection, Sexual Conflict, and the Evolution of Gamete Recognition Proteins in the Sea.

Don R. Levitan. 2018. American Naturalist. 191:1, 88-105

Dr. Levitan’s recent publication in the American Naturalist is a result of intensive field experiments conducted at BMSC since 2011. Our 2012 Science Diving class was part of the field crew to assist with this research.

“Field experiments and a simple heuristic model examining the degree of sperm mixing for the sea urchin sea urchin, Strongylocentrotus franciscanus, indicate that degree of competitive fertilization depends on density and distribution of competing males, and that the nature of this competition influences whether males with high- or low-affinity gamete recognition protein genotypes have higher reproductive success. These results provide a potential explanation for the generation and maintenance of variation in gamete recognition proteins and why effectiveness of conspecific sperm precedence can be density dependent.”