Male reproductive success and body size in Atlantic cod Gadus
morhua L.
A. Rakitin, M.M. Ferguson, E.A. Trippel-2001
Marine Biology, 138(6):
1077-1085
Abstract:
Body size is often positively associated with mating
success in fish. However, mating success may not accurately represent
reproductive success (number of progeny produced). We tested the null
hypothesis that reproductive success in male Atlantic cod, Gadus morhua,
is not directly proportional to body size. Two allozyme loci and one
minisatellite locus were used to estimate the proportion of larvae sired by
pairs of males differing in body size and spawning with one female in each
of eight tanks during an entire spawning season. Genotypes of progeny from
51 spawning events (egg batches) showed that both males fertilised eggs in
each tank. Multiple paternity of larvae occurred in 35 batches. The
estimated proportion of larvae sired by each male varied randomly among egg
batches within tanks. Male size, condition factor, and total or relative
body-weight loss over the season were not correlated with the estimated
proportion of larvae sired by each male during the spawning season. Relative
activity of males was marginally associated with male reproductive success,
with more active males siring a larger proportion of larvae. Male
reproductive success was affected by female size, with males much larger
(>25% total length) than females siring a smaller proportion of larvae.
(Department of Zoology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1, Tel: +1-519-8244120 ext 2726, Fax: +1-519-7671656, E-mail of M.M. Ferguson: mmfergus@uoguelph.ca)