Assessing the potential for post-ejaculatory female choice in a polyandrous beach-spawning fish

Area of Science:

• Reproductive Biology
• Sexual Selection
• Ichthyology

Background:

• Post-ejaculatory sexual selection, including cryptic female choice, can influence fertilization success in species with limited pre-ejaculatory mate choice.
• Cryptic female choice often involves female-mediated differential fertilization bias through chemical cues affecting sperm performance.

Purpose of the Study:

• To investigate the role of female chemical cues in modulating sperm swimming characteristics in beach-spawning capelin (Mallotus villosus).
• To assess the potential for cryptic female choice and assortative mating based on body size in capelin.

Main Methods:

• Assayed sperm swimming characteristics under varying doses and origins of egg cues.
• Examined mating groups for size association and ejaculate quality in relation to male body size.

Main Results:

• Mating groups in capelin were not associated by body size.
• Larger males did not produce ejaculates with superior sperm swimming characteristics.
• Egg cues, irrespective of dosage or donor, did not influence sperm swimming performance.

Conclusions:

• Female chemical cues do not appear to play a significant role in sperm selection in capelin.
• Both pre-ejaculatory sexual selection and cryptic female choice mediated by female chemical cues seem underdeveloped in capelin.
• Reproductive constraints may limit the evolution of these sexual selection mechanisms in this species.