Data from: Ejaculate evolution in external fertilizers: influenced by sperm competition or sperm limitation?

The evolution of sperm quality and quantity is shaped by various selective processes, with sperm competition generally considered the primary selective agent. Particularly in external fertilizers, however, sperm limitation through gamete dispersal can also influence gamete investments, but empirical data examining this effect are limited. Here, we studied the relative importance of sperm competition and the spawning conditions in explaining the macroevolutionary patterns of sperm size and number within two taxa with external fertilization but differences in their reproductive biology. In frogs, sperm swim slowly but for up to hours as they penetrate the gelatinous egg coating, whereas fish sperm typically swim fast, are very short-lived (seconds to minutes), and often face a relatively higher risk of being moved away from the ova by currents. Our phylogenetic models and path analyses revealed different trajectories of ejaculate evolution in these two taxa. Sperm size and number responded primarily to variation in sperm competition in the anurans, but more strongly to egg number and water turbulence in the fishes. Whereas the results across anurans align with the general expectation that sexual selection is the main driver of ejaculate evolution, our findings across the fishes suggest that sperm limitation has been underappreciated.Data frogsData of the 130 anuran species used in this study, including spawning site occurrence of foam nesting, mating system/amplexus, oviposition substrate site, oviposition type, egg capsule consistency, water type, male body mass (in g), combined testes mass (in mg), total sperm length (in µm), sperm head length (in µm), sperm flagellum length (in µm), sperm number (in million), female snout-vent length (in mm), clutch size, and egg diameter (in mm). OD in the references refers to own data.Data_frogs.txtData fishesData of the 57 fish species used in this study, including male body mass (in g), combined testes mass (in g), the presence or absence of hormonal induction of sperm production, sperm number (in billions), total sperm length (in µm), average-path sperm velocity (in µm/s), sperm longevity (in s), female body mass (in g), egg diameter (in mm), egg number (in thousands), the type of spawning water, spawning site, and mating system.Data_fishes.txtPhylogeny frogsPhylogenetic reconstruction for the 130 anurans used in this studyPhylogeny_frogs.nexPhylogeny fishesPhylogenetic reconstruction for the 57 fishes used in this studyPhylogeny_fish.ne