costs of reproduction and terminal investment by females in a semelparous marsupial繁殖和终端的成本投资由女性semelparous袋.pdf
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Costs of Reproduction and Terminal Investment by
Females in a Semelparous Marsupial
Diana O. Fisher1,2*, Simon P. Blomberg1
1 School of Biological Sciences, The University of Queensland, St Lucia, Australia, 2 Research School of Biology, Australian National University, Canberra, Australia
Abstract
Evolutionary explanations for life history diversity are based on the idea of costs of reproduction, particularly on the concept
of a trade-off between age-specific reproduction and parental survival, and between expenditure on current and future
offspring. Such trade-offs are often difficult to detect in population studies of wild mammals. Terminal investment theory
predicts that reproductive effort by older parents should increase, because individual offspring become more valuable to
parents as the conflict between current versus potential future offspring declines with age. In order to demonstrate this
phenomenon in females, there must be an increase in maternal expenditure on offspring with age, imposing a fitness cost
on the mother. Clear evidence of both the expenditure and fitness cost components has rarely been found. In this study, we
quantify costs of reproduction throughout the lifespan of female antechinuses. Antechinuses are nocturnal, insectivorous,
forest-dwelling small (20–40 g) marsupials, which nest in tree hollows. They have a single synchronized mating season of
around three weeks, which occurs on predictable dates each year in a population. Females produce only one litter per year.
Unlike almost all other mammals, all males, and in the smaller species, most females are semelparous. We show that
increased allocation to current reproduction reduces maternal survival, and that offspring growth and survival in the first
breeding season is traded-off with performance of the second litter in iteroparous females. In iteroparous females, increas
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