A skew model for the evolution of sociality via manipulation: why it is better to be feared than loved

Crespi, Bernard J.; Ragsdale, Janice E.

doi:10.1098/rspb.2000.1077

Cited by 72 publications

(42 citation statements)

References 87 publications

(94 reference statements)

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“…Ö st et al 2003b) and may therefore adjust their level of vigilance accordingly to comply with their coalition partners' demands. Individuals often have to compromise their own activity budgets to avoid social costs such as intragroup aggression and the risk of eviction (Johnstone and Cant 1999;Crespi and Ragsdale 2000). The commonly observed "group-size effect" on vigilance, with individual levels of antipredatory vigilance declining with group size (e.g., Roberts 1996), could also explain our first prediction.…”

Section: Testing the Model Predictionssupporting

confidence: 58%

Parental Effort and Reproductive Skew in Coalitions of Brood Rearing Female Common Eiders

Öst¹,

Clark²,

Kilpi³

et al. 2007

The American Naturalist

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Members of breeding groups face conflicts over parental effort when balancing antipredatory vigilance and feeding. Empirical evidence has shown disparate responses to manipulations of parental effort. We develop a model in which we determine the evolutionarily stable effort of partners given their body conditions, allowing the benefits of shared care to be unevenly divided, and we test this model's predictions with data on common eiders (Somateria mollissima). Eiders show uniparental female care; females may share brood rearing, or they may tend alone, and their body condition at hatching of the young shows large environmentally induced variation. The model predicts that parental effort (vigilance) in a coalition is lower than when tending alone, controlling for parental condition; this prediction is supported by the data. The parental effort in a coalition should be positively correlated with body condition, and this prediction is also supported. Finally, parental effort should increase when partner condition decreases and vice versa; this prediction is partially supported. The Nash bargaining game may provide promising avenues by which to determine the precise settlement of reproductive skew and effort between coalition partners in the future.

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Section: Testing the Model Predictionssupporting

confidence: 58%

Parental Effort and Reproductive Skew in Coalitions of Brood Rearing Female Common Eiders

Öst¹,

Clark²,

Kilpi³

et al. 2007

The American Naturalist

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“…Other factors, such as parental manipulation (Alexander 1974;Michener and Brothers 1974;Craig 1983;Crespi and Ragsdale 2000) or variation in resource (pollen) quantity and quality (Roulston and Cane 2002), may also generate variation in body size. The patterns that we document depend on social context: Megalopta caste expression is not a direct result of size per se, but of size relative to nest mates.…”

Section: £)Spr Ngermentioning

confidence: 99%

Body Size Shapes Caste Expression, and Cleptoparasitism Reduces Body Size in the Facultatively Eusocial Bees Megalopta (Hymenoptera: Halictidae)

2008

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We used the facultatively social sweat bee Megalopta genalis (Halictidae) to test whether body size is associated with social caste. Behavioral observations showed that non-reproductive foragers were significantly smaller than reproductive nest mate queens, and foragers were also smaller than presumed pre-dispersal reproductives. Moreover, among females from field-collected nests without behavioral observations, relative body size correlated with relative ovary size. Reproductive status is not a direct result of body size, as body size was not significantly associated with either ovary size or fecundity among both solitary and social reproductives. Reproductive status is apparently an outcome of social competition for reproductive dominance, and status is influenced by size relative to nest mates. Our study is the first to demonstrate an association of body size with caste expression in a facultatively social species with relatively weak seasonal constraints on independent nesting. Larvae of a parasitic fly (Fiebrigella sp., Chloropidae) consume pollen provisions stored in nest cells of M. genalis and M. ecuadoria. We tested whether fly parasitism of M. genalis reduces body size. Parasitized females are significantly smaller as adults than their unparasitized nestmates. This reduction is of a similar magnitude to the size differences between castes, and has the potential to shape host reproductive options by influencing competition with nest mates. We present data on the prevalence of parasitism from four collections of M. genalis and two collections of M. ecuadoria from Barro Colorado Island, Panama, and La Selva, Costa Rica.

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“…It is often assumed that insect body size generally correlates with reproductive ability (e.g. Lin & Michener 1972;Crespi & Ragsdale 2000), although the evidence across bee species is mixed (Bosch & Vicens 2006) and there is presently no evidence supporting the subfertility hypothesis in a facultatively social bee or wasp (Field & Foster 1999).…”

mentioning

confidence: 99%

Social competition but not subfertility leads to a division of labour in the facultatively social sweat bee Megalopta genalis (Hymenoptera: Halictidae)

et al. 2009

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A skew model for the evolution of sociality via manipulation: why it is better to be feared than loved

Cited by 72 publications

References 87 publications

Parental Effort and Reproductive Skew in Coalitions of Brood Rearing Female Common Eiders

Parental Effort and Reproductive Skew in Coalitions of Brood Rearing Female Common Eiders

Body Size Shapes Caste Expression, and Cleptoparasitism Reduces Body Size in the Facultatively Eusocial Bees Megalopta (Hymenoptera: Halictidae)

Social competition but not subfertility leads to a division of labour in the facultatively social sweat bee Megalopta genalis (Hymenoptera: Halictidae)

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