Reproductive costs in eastern grey kangaroo females, the bigger picture

Poster session
Partie de:
vendredi 20 déc. 11:30 AM (1 heure)
Dîner   12:30 PM à 01:30 PM (1 heure)
Salle ABCD
Life history theory assumes that individuals dispose of a limited energetic budget. Thus, they face allocation trade-offs between different fitness components such as current and future reproduction, growth, or survival. These trade-offs can be seen as costs of one function over another and are often observed when resources are scarce. We studied allocation trade-offs in females of an iteroparous marsupial with indeterminate growth, the eastern grey kangaroo, to determine how current reproduction affected skeletal growth and changes in body mass, fecundity and weaning success the following year, and survival. Our analyses controlled for variability in maternal age, body mass and size, as well as resource availability. We used data from a 10-year project that closely monitors over 100 marked adult females each year. We found important costs of reproduction on subsequent skeletal growth (body growth), reproduction (fecundity and weaning success), maintenance (mass change) and on survival. These effects are correlated with the effort allocated to current reproduction: females that did not reproduce grew more and accumulated more mass than females that reproduced. Among reproductive females, those that weaned their young had lower growth and greater mass loss than females whose young died before weaning. Although food availability had an overall positive effect on mass gain, skeletal growth, reproductive success and survival, the costs of reproduction appeared mostly independent of forage availability, which had a positive effect on yearly mass change and on following year fecundity only for females that weaned a young.

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