Mushroom Body Volume Is Related to Social Aggression and Ovary Development in the Paperwasp <i>Polistes instabilis</i>

Yamile Molina; Sean O’Donnell

doi:10.1159/000102975

Mushroom Body Volume Is Related to Social Aggression and Ovary Development in the Paperwasp Polistes instabilis

Brain Behavior and Evolution ◽

10.1159/000102975 ◽

2007 ◽

Vol 70 (2) ◽

pp. 137-144 ◽

Cited By ~ 34

Author(s):

Yamile Molina ◽

Sean O’Donnell

Keyword(s):

Mushroom Body ◽

Social Aggression ◽

Ovary Development ◽

Body Volume ◽

Polistes Instabilis

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Cumulative Effects of Foraging Behavior and Social Dominance on Brain Development in a Facultatively Social Bee (Ceratina australensis)

Brain Behavior and Evolution ◽

10.1159/000381414 ◽

2015 ◽

Vol 85 (2) ◽

pp. 117-124 ◽

Cited By ~ 11

Author(s):

Sandra M. Rehan ◽

Susan J. Bulova ◽

Sean O''Donnell

Keyword(s):

Brain Development ◽

Task Performance ◽

Mushroom Body ◽

Cumulative Effects ◽

Body Volume ◽

Total Brain Volume ◽

Carpenter Bee ◽

The Social ◽

Foraging Experience ◽

Mushroom Body Calyx

In social insects, both task performance (foraging) and dominance are associated with increased brain investment, particularly in the mushroom bodies. Whether and how these factors interact is unknown. Here we present data on a system where task performance and social behavior can be analyzed simultaneously: the small carpenter bee Ceratina australensis. We show that foraging and dominance have separate and combined cumulative effects on mushroom body calyx investment. Female C. australensis nest solitarily and socially in the same populations at the same time. Social colonies comprise two sisters: the social primary, which monopolizes foraging and reproduction, and the social secondary, which is neither a forager nor reproductive but rather remains at the nest as a guard. We compare the brains of solitary females that forage and reproduce but do not engage in social interactions with those of social individuals while controlling for age, reproductive status, and foraging experience. Mushroom body calyx volume was positively correlated with wing wear, a proxy for foraging experience. We also found that, although total brain volume did not vary among reproductive strategies (solitary vs. social nesters), socially dominant primaries had larger mushroom body calyx volumes (corrected for both brain and body size variation) than solitary females; socially subordinate secondaries (that are neither dominant nor foragers) had the least-developed mushroom body calyces. These data demonstrate that sociality itself does not explain mushroom body volume; however, achieving and maintaining dominance status in a group was associated with mushroom body calyx enlargement. Dominance and foraging effects were cumulative; dominant social primary foragers had larger mushroom body volumes than solitary foragers, and solitary foragers had larger mushroom body volumes than nonforaging social secondary guards. This is the first evidence for cumulative effects on brain development by dominance and task performance.

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The Loss of Sociality Is Accompanied by Reduced Neural Investment in Mushroom Body Volume in the Sweat Bee Augochlora Pura (Hymenoptera: Halictidae)

Annals of the Entomological Society of America ◽

10.1093/aesa/saaa019 ◽

2020 ◽

Author(s):

Sarah Pahlke ◽

Marc A Seid ◽

Sarah Jaumann ◽

Adam Smith

Keyword(s):

Social Behavior ◽

Social Interactions ◽

Distributed Cognition ◽

Mushroom Body ◽

Brain Area ◽

Brain Evolution ◽

Body Volume ◽

Social Brain ◽

The Social ◽

Mosaic Brain Evolution

Abstract Social behavior has been predicted to select for increased neural investment (the social brain hypothesis) and also to select for decreased neural investment (the distributed cognition hypothesis). Here, we use two related bees, the social Augochlorella aurata (Smith) (Hymenoptera: Halictidae) and the related Augochlora pura (Say), which has lost social behavior, to test the contrasting predictions of these two hypotheses in these taxa. We measured the volumes of the mushroom body (MB) calyces, a brain area shown to be important for cognition in previous studies, as well as the optic lobes and antennal lobes. We compared females at the nest foundress stage when both species are solitary so that brain development would not be influenced by social interactions. We show that the loss of sociality was accompanied by a loss in relative neural investment in the MB calyces. This is consistent with the predictions of the social brain hypothesis. Ovary size did not correlate with MB calyx volume. This is the first study to demonstrate changes in mosaic brain evolution in response to the loss of sociality.

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