Abstract:
I examined two aspects of the reproductive behavior
of the garibaldi, Hypsypops rubicundus, a temperate
marine damselfish with male parental care. My primary
objective was to determine the relationship between
female choice and male parental investment in the care
of offspring. In particular, I sought to determine: (1)
how the presence and developmental stage of eggs already
in the nest influences female spawning site choice; (2)
how male investment in current offspring varies with the
number and developmental stage of eggs in his nest; and
(3) how patterns of mate choice and parental investment
contribute to the reproductive success of each sex.
Because male courtship and parental care behaviors
change during a nesting cycle, a secondary objective was
to indentify associated hormonal changes that
potentially cause this change in behavior.
Female garibaldi showed a strong preference to
spawn in nests with early stage eggs over empty nests or
those with predominantly late-stage eggs. Within nests
containing eggs in multiple stages of development,
females always deposited their eggs among the youngest
eggs in the nest. Male garibaldi exhibited behavioral
tactics that would increase the mortality of eggs
deposited in empty nests (first clutches) or in older
broods (late clutches) and thus favor such female
preference. These include: (1) cannibalism of
single-clutch broods; (2) cannibalism of older eggs
early in the brood-cycle; (3) cannibalism of younger
eggs late in the brood-cycle; (4) increased
attentiveness of larger broods; and (5) increased
aggressiveness in defense of larger broods. These
behaviors are consistent with the predictions of
parental investment theory that males invest in current
offspring in a way that maximizes the net (current plus
future) benefits of paternal care.
Male garibaldi actively courted females when their
nests were empty. However, courtship rates declined as
males acquired eggs and as those eggs aged. This was
concomitant with an increase in parental egg fanning.
Levels of both testosterone and 11-ketotestosterone were
positively related to levels of courtship activity and
inversely related to male parental egg-fanning.
