Transactional Skew and Assured Fitness Return Models Fail to Predict Patterns of Cooperation in Wasps

Cooperative breeders often exhibit reproductive skew, where dominant individuals reproduce more than subordinates. Two approaches derived from Hamilton’s inclusive fitness model predict when subordinate behavior is favored over living solitarily. The assured fitness return (AFR) model predicts that...

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Bibliographic Details
Published in:The American naturalist 2006-04, Vol.167 (4), p.467-480
Main Authors: Nonacs, Peter, Liebert, Aviva E., Starks, Philip T.
Format: Article
Language:English
Subjects:
Animal behavior
Animal nesting
Animal reproduction
Animals
Behavior, Animal
Biological Evolution
Cooperation
Cooperative Behavior
Cousins
Evolution
Female
Female animals
Insects
Male
Modeling
Models, Biological
Polistes
Predictions
Productivity
Reproduction
Sex ratio
Sexual reproduction
Survival rates
Wasps - physiology
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Summary:Cooperative breeders often exhibit reproductive skew, where dominant individuals reproduce more than subordinates. Two approaches derived from Hamilton’s inclusive fitness model predict when subordinate behavior is favored over living solitarily. The assured fitness return (AFR) model predicts that subordinates help when they are highly likely to gain immediate indirect fitness. Transactional skew models predict dominants and subordinates “agree” on a level of reproductive skew that induces subordinates to join groups. We show the AFR model to be a special case of transactional skew models that assumes no direct reproduction by subordinates. We use data from 11 populations of four wasp species (Polistes,Liostenogaster) as a test of whether transactional frameworks suffice to predict when subordinate behavior should be observed in general and the specific level of skew observed in cooperative groups. The general prediction is supported; in 10 of 11 cases, transactional models correctly predict presence or absence of cooperation. In contrast, the specific prediction is not consistent with the data. Where cooperation occurs, the model accurately predicts highly biased reproductive skew between full sisters. However, the model also predicts that distantly related or unrelated females should cooperate with low skew. This prediction fails: cooperation with high skew is the observed norm. Neither the generalized transactional model nor the special‐case AFR model can explain this significant feature of wasp sociobiology. Alternative, nontransactional hypotheses such as parental manipulation and kin recognition errors are discussed.
ISSN:0003-0147
1537-5323
DOI:10.1086/501168