Postcopulatory sexual selection is associated with accelerated evolution of sperm morphology.

摘要: Rapid diversification of sexual traits is frequently attributed to selection, though explicit tests this hypothesis remain limited. Spermatozoa exhibit remarkable variability in size and shape, studies report a correlation between sperm morphology (sperm length shape) competition risk or female reproductive tract morphology. However, whether postcopulatory processes (e.g., cryptic choice) influence the speed evolutionary form unknown. Using passerine birds, we quantified rates divergence among lineages (i.e., species pairs) determined these varied with level (estimated as relative testes mass). We found that mass was significantly positively associated more rapid phenotypic midpiece flagellum lengths, well total length. In contrast, there no association head size, models suggested evolutionarily constrained. Our results are first show an strength evolution, suggest selection promotes