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Social complexity influences brain investment and neural operation costs in ants

journal contribution
posted on 12.04.2022, 00:48 by J Frances Kamhi, Wulfila Gronenberg, Simon RobsonSimon Robson, James FA Traniello
The metabolic expense of producing and operating neural tissue required for adaptive behaviour is considered a significant selective force in brain evolution. In primates, brain size correlates positively with group size, presumably owing to the greater cognitive demands of complex social relationships in large societies. Social complexity in eusocial insects is also associated with large groups, as well as collective intelligence and division of labour among sterile workers. However, superorganism phenotypes may lower cognitive demands on behaviourally specialized workers resulting in selection for decreased brain size and/or energetic costs of brain metabolism. To test this hypothesis, we compared brain investment patterns and cytochrome oxidase (COX) activity, a proxy for ATP usage, in two ant species contrasting in social organization. Socially complex Oecophylla smaragdina workers had larger brain size and relative investment in the mushroom bodies (MBs)-higher order sensory processing compartments-than the more socially basic Formica subsericea workers. Oecophylla smaragdina workers, however, had reduced COX activity in the MBs. Our results suggest that as in primates, ant group size is associated with large brain size. The elevated costs of investment in metabolically expensive brain tissue in the socially complex O. smaragdina, however, appear to be offset by decreased energetic costs.

Funding

Category 1 - Australian Competitive Grants (this includes ARC, NHMRC)

History

Volume

283

Issue

1841

Start Page

1

End Page

9

Number of Pages

9

eISSN

1471-2954

ISSN

0962-8452

Location

England

Publisher

The Royal Society Publishing

Language

eng

Peer Reviewed

Yes

Open Access

No

Acceptance Date

26/09/2016

External Author Affiliations

University of Arizona, Boston University, USA

Era Eligible

Yes

Medium

Print

Journal

Proceedings of the Royal Society B: Biological Sciences

Article Number

20161949