Limits...
Costs of reproduction and terminal investment by females in a semelparous marsupial.

Fisher DO, Blomberg SP - PLoS ONE (2011)

Bottom Line: Clear evidence of both the expenditure and fitness cost components has rarely been found.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.Iteroparity did not increase lifetime reproductive success, indicating that terminal investment in the first breeding season at the expense of maternal survival (i.e. semelparity) is likely to be advantageous for females.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, The University of Queensland, St. Lucia, Australia. d.fisher@uq.edu.au

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, increased allocation to second litters is associated with severe weight loss in late lactation and post-lactation death of mothers, but increased offspring growth in late lactation and survival to weaning. These findings are consistent with terminal investment. Iteroparity did not increase lifetime reproductive success, indicating that terminal investment in the first breeding season at the expense of maternal survival (i.e. semelparity) is likely to be advantageous for females.

Show MeSH
Survival to weaning of nestlings with mothers that were semelparous, iteroparous with first litters, or iteroparous with second litters.Error bars are standard errors.
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pone-0015226-g002: Survival to weaning of nestlings with mothers that were semelparous, iteroparous with first litters, or iteroparous with second litters.Error bars are standard errors.

Mentions: As expected from the reduced expenditure by their mothers, most offspring of iteroparous females in their first breeding season died before weaning. If females show terminal allocation, we expected offspring performance of mothers in their second season to increase in comparison to that of mothers in their first season. As expected, most offspring of mothers in their second breeding season survived to weaning (Fig. 2). This difference was significant (z = 3.6, P = 0.0004, overall model:  = 15, P = 0.0006), but the difference between offspring survival of semelparous mothers and iteroparous mothers in their first breeding season was not significant (z = 1.5, P = 0.13). Offspring mortality peaked in the last month of lactation and around the time of weaning in December and early January in both years (Fig. 3).


Costs of reproduction and terminal investment by females in a semelparous marsupial.

Fisher DO, Blomberg SP - PLoS ONE (2011)

Survival to weaning of nestlings with mothers that were semelparous, iteroparous with first litters, or iteroparous with second litters.Error bars are standard errors.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3020937&req=5

pone-0015226-g002: Survival to weaning of nestlings with mothers that were semelparous, iteroparous with first litters, or iteroparous with second litters.Error bars are standard errors.
Mentions: As expected from the reduced expenditure by their mothers, most offspring of iteroparous females in their first breeding season died before weaning. If females show terminal allocation, we expected offspring performance of mothers in their second season to increase in comparison to that of mothers in their first season. As expected, most offspring of mothers in their second breeding season survived to weaning (Fig. 2). This difference was significant (z = 3.6, P = 0.0004, overall model:  = 15, P = 0.0006), but the difference between offspring survival of semelparous mothers and iteroparous mothers in their first breeding season was not significant (z = 1.5, P = 0.13). Offspring mortality peaked in the last month of lactation and around the time of weaning in December and early January in both years (Fig. 3).

Bottom Line: Clear evidence of both the expenditure and fitness cost components has rarely been found.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.Iteroparity did not increase lifetime reproductive success, indicating that terminal investment in the first breeding season at the expense of maternal survival (i.e. semelparity) is likely to be advantageous for females.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, The University of Queensland, St. Lucia, Australia. d.fisher@uq.edu.au

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, increased allocation to second litters is associated with severe weight loss in late lactation and post-lactation death of mothers, but increased offspring growth in late lactation and survival to weaning. These findings are consistent with terminal investment. Iteroparity did not increase lifetime reproductive success, indicating that terminal investment in the first breeding season at the expense of maternal survival (i.e. semelparity) is likely to be advantageous for females.

Show MeSH