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Young FJ, Alcalde Anton A, Melo-Flórez L, Couto A, Foley J, Monllor M, McMillan WO, Montgomery SH. Enhanced long-term memory and increased mushroom body plasticity in Heliconius butterflies. iScience 2024; 27:108949. [PMID: 38357666 PMCID: PMC10864207 DOI: 10.1016/j.isci.2024.108949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 11/27/2023] [Accepted: 01/15/2024] [Indexed: 02/16/2024] Open
Abstract
Heliconius butterflies exhibit expanded mushroom bodies, a key brain region for learning and memory in insects, and a novel foraging strategy unique among Lepidoptera - traplining for pollen. We tested visual long-term memory across six Heliconius and outgroup Heliconiini species. Heliconius species exhibited greater fidelity to learned colors after eight days without reinforcement, with further evidence of recall at 13 days. We also measured the plastic response of the mushroom body calyces over this time period, finding substantial post-eclosion expansion and synaptic pruning in the calyx of Heliconius erato, but not in the outgroup Heliconiini Dryas iulia. In Heliconius erato, visual associative learning experience specifically was associated with a greater retention of synapses and recall accuracy was positively correlated with synapse number. These results suggest that increases in the size of specific brain regions and changes in their plastic response to experience may coevolve to support novel behaviors.
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Affiliation(s)
- Fletcher J. Young
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- Smithsonian Tropical Research Institute, Gamboa, Panama
- School of Biological Science, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Amaia Alcalde Anton
- School of Biological Science, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | | | - Antoine Couto
- School of Biological Science, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Jessica Foley
- Smithsonian Tropical Research Institute, Gamboa, Panama
- School of Biological Science, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | | | | | - Stephen H. Montgomery
- Smithsonian Tropical Research Institute, Gamboa, Panama
- School of Biological Science, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
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