Age-specific reproductive investment in female burying beetles: independent effects of state and risk of death

Cotter, Sheena C. and Ward, Richard J. S. and Kilner, Rebecca M. (2011) Age-specific reproductive investment in female burying beetles: independent effects of state and risk of death. Functional Ecology, 25 (3). pp. 652-660. ISSN 0269-8463

Full content URL: http://dx.doi.org/10.1111/j.1365-2435.2010.01819.x

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Abstract

1. How much should an individual invest in reproduction as it grows older? Answering this question involves determining whether individuals measure their age as the time left for future reproduction or as the rate of deterioration in their state. Theory suggests that in the former case individuals should increase their allocation of resources to reproduction as opportunities for future breeding dwindle, and terminally invest when they breed for the last time. In the latter case they should reduce their investment in reproduction with age, either through adaptive reproductive restraint or as a passive by-product of senescence.
2. Here we present the results of experiments on female burying beetles, Nicrophorus vespilloides, in which we independently manipulated the perceived risk of death (by activating the immune system) and the extent of deterioration in state (by changing age of first reproduction and/or prior investment in reproduction).
3. We found that the risk of death and state each independently influenced the extent of reproductive investment. Specifically, we found a state-dependent decline in reproductive investment as females grew older that could be attributed to both adaptive reproductive restraint and senescence. A perceived increase in the risk of death, induced by activation of the immune system, caused females to switch from a strategy of reproductive restraint to terminal investment. Nevertheless, absolute reproductive investment was lower in older females, indicating constraints of senescence.
4. Our results show that a decline in reproductive investment with age does not necessarily constitute evidence of reproductive senescence but can also result from adaptive reproductive restraint.
5. Our results further suggest that the extent of reproductive investment is dependent on several different intrinsic cues and that the particular blend of cues available at any given age can yield very different patterns of investment. Perhaps this explains why age-related reproductive investment patterns seen in nature are so diverse.

Additional Information:Article first published online: 23 DEC 2010
Keywords:Ageing, immunity, life history strategy, parental care, reproductive restraint, senescence, state-dependent, terminal investment
Subjects:C Biological Sciences > C182 Evolution
C Biological Sciences > C150 Environmental Biology
C Biological Sciences > C340 Entomology
C Biological Sciences > C180 Ecology
C Biological Sciences > C120 Behavioural Biology
C Biological Sciences > C300 Zoology
C Biological Sciences > C110 Applied Biology
C Biological Sciences > C100 Biology
Divisions:College of Science > School of Life Sciences
ID Code:16022
Deposited On:16 Nov 2014 17:02

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