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Published on: October 13, 2018
Terminal reproductive effort in a marsupial
Joanne L Isaac1, Christopher N Johnson
1School of Tropical Biology, James Cook University, Townsville, Quenslannd 4811, Australia. joanne.isaac@jcu.edu.au
Biology Letters
|December 7, 2006
Summary
Older female possums increase reproductive effort (RE) near the end of their lives, losing more mass during lactation. This supports terminal RE in mammals, unlike in many other species.
Area of Science:
- Evolutionary biology
- Reproductive strategies
- Mammalian life history
Background:
- Life-history theory predicts increased reproductive effort (RE) with age.
- Mammalian studies often show no age-related variation in RE.
- Offspring control of energy transfer may constrain maternal RE in eutherian mammals.
Purpose of the Study:
- To investigate age-specific reproductive effort (RE) in marsupials.
- To test the hypothesis of terminal RE in a marsupial species.
- To examine the relationship between maternal age and RE in the common brushtail possum.
Main Methods:
- Analysis of age-specific reproductive effort (RE) in common brushtail possums.
- Measuring RE as the proportion of maternal mass lost during lactation.
- Correlating RE with offspring mass, birth timing, and litter size.
Main Results:
- Reproductive effort (RE) was strongly correlated with yearling offspring mass.
- Older female possums exhibited higher RE.
- Older females gave birth earlier and had a higher likelihood of producing two offspring annually.
Conclusions:
- Marsupial maternal control of lactation allows for greater variation in RE.
- Results provide strong evidence for terminal RE in the common brushtail possum.
- High RE in one season led to reduced maternal mass at the start of the next breeding season.
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