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Maternal costs in offspring production affect investment rules in joint rearing


Type

Article

Change log

Authors

Savage, JL 
Russell, AF 
Johnstone, RA 

Abstract

When multiple individuals contribute to rearing the same offspring, conflict is expected to occur over the relative amounts invested by each carer. Existing models of biparental care suggest that this conflict should be resolved by partially compensating for changes by co-investors, but this has yet to be explicitly modeled in cooperative breeders over a range of carer numbers. In addition, existing models of biparental and cooperative care ignore potential variation in both the relative costs of offspring production to mothers and in maternal allocation decisions. If mothers experience particularly high costs during offspring production, this might be expected to affect their investment strategies during later offspring care. Here we show using a game-theoretical model that a range of investment tactics can result depending on the number of carers and the relative costs to the mother of the different stages within the breeding attempt. Additional carers result in no change in investment by individuals when production costs are low, as mothers can take advantage of the greater potential investment by increasing offspring number; however this tactic ultimately results in a decrease in care delivered to each offspring. Conversely, when production costs prevent the mother from increasing offspring number, our model predicts that other individuals should partially compensate for additional carers and hence offspring should each receive a greater amount of care. Our results reinforce the importance of considering investment across all stages in a breeding attempt, and provide some explanatory power for the variation in investment rules observed across cooperative species.

Description

Keywords

biparental care, cooperative breeding, game theory, incomplete compensation, maternal effects, sealed-bid

Journal Title

Behavioral Ecology

Conference Name

Journal ISSN

1045-2249
1465-7279

Volume Title

24

Publisher

Oxford University Press (OUP)

Rights

DSpace@Cambridge license
Sponsorship
This work was supported by a Natural Environment Research Council studentship to JLS, and by a Royal Society University Research Fellowship to AFR.