Sperm competition and fertilization success in Atlantic cod ( Gadus morhua ): effect of sire size and condition factor on gamete quality

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Rakitin, Ana, Ferguson, Moira M, Trippel, Edward A
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1999
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; atlantic cod; Gadus morhua
• Online Access: http://dx.doi.org/10.1139/f99-164; http://www.nrcresearchpress.com/doi/pdf/10.1139/f99-164

Sperm competition experiments were conducted to test the null hypothesis that sperm quality is not affected by male body size in Atlantic cod (Gadus morhua). Genetic markers (allozymes) were used to determine the proportion of larvae sired by pairs of males when their sperm was combined with eggs of a single female simultaneously. Significant differences in fertilization success between males were not explained by differences in body size. Fertilization success was positively associated with male condition factor (K) and with spermatozoa density in each male's semen when equal volumes of semen from each male were used. Male K was positively associated with male fertilization success when the volume of semen used from each male was adjusted to add approximately equal numbers of spermatozoa from each male. The relative fertilization success of males varied depending on which female was the egg donor, suggesting that female "choice" at the gamete level may be occurring in cod.