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Social modulation of sex steroid concentrations in the urine of male cichlid fish Oreochromis mossambicus
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Advisor(s)
Abstract(s)
The relationship between urinary concentrations (free +
sulfates + glucuronides) of the steroids testosterone (T),
11-ketotestosterone (11KT), 17α, 20ß-dihydroxy-4-preg-
nen-3-one (17,20ß-P) and 17a,20a-dihydroxy-4-preg-
nen-3-one (17,20α-P), and the social behavior of males
of the cichlid fish Oreochromis mossambicus was inves-
tigated. After 8 days of isolation none of the steroids
were good predictors of social dominance developed
after subsequent formation of all-male groups. One day
after group formation dominance indexes were good
predictors of the urine concentrations of all sex steroids.
Dominance indexes and androgen concentrations mea-
sured after all-male group formation were positively cor-
related with territoriality, courtship rate, and nest size.
Similar relationships were found for progestins with the
exception that they were not correlated with courtship
rate. All-male group formation was also accompanied by
an increase in urinary sex steroid concentrations in fish
that became territorial and a decrease in non-territorial
fish with the exception of T, which increased in both
groups. Addition of ovulating females caused steroid
concentrations to return to levels near isolation, except
for 17,20α-P in territorials, which underwent a large in-
crease. Thus, social interactions may have an important
modulatory effect on sex steroid concentrations in O.
mossambicus.
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Citation
Oliveira, R. F.; Almada, V. C.; Canario, A. V. M. Social modulation of sex steroid concentrations in the urine of male cichlid fish Oreochromis mossambicus, Hormones and Behavior, 30, 1, 2-12, 1996.