Fig. 4.

Evolutionary conservation of the sperm motility activation pathway across Metazoan phyla. (Left) Sperm release strategies among the phyla. Spawning refers to release of sperm into an external aquatic environment for internal or external fertilization. Copulation refers to direct sperm transfer and internal fertilization. (Middle) Phyla in which one or more species exhibit cAMP-dependent sperm motility. (Right) Phyla in which one or more species have sAC, SLC9C1, or CatSper expression confirmed in sperm (blue), encoded in the genome (teal), or absent from all available genomes (gray). White circles indicate that no data were found in the published literature.