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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Moura PA, Young FJ, Monllor M, Cardoso MZ, Montgomery SH. Long-term spatial memory across large spatial scales in Heliconius butterflies. Curr Biol 2023; 33:R797-R798. [PMID: 37552941 DOI: 10.1016/j.cub.2023.06.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 06/01/2023] [Accepted: 06/02/2023] [Indexed: 08/10/2023]
Abstract
Locating food in heterogeneous environments is a core survival challenge. The distribution of resources shapes foraging strategies, imposing demands on perception, learning and memory, and associated brain structures. Indeed, selection for foraging efficiency is linked to brain expansion in diverse taxa, from primates1 to Hymenopterans2. Among butterflies, Heliconius have a unique dietary adaptation, actively collecting and feeding on pollen, providing a source of essential amino acids as adults, negating reproductive senescence and facilitating an extended longevity3. Several lines of evidence suggest that Heliconius learn the spatial location of pollen resources within an individual's home range4, and spatial learning may be more pronounced at these large spatial scales. However, experimental evidence of spatial learning in Heliconius, or any other butterfly, is so far absent. We therefore tested the ability of Heliconius to learn the spatial location of food rewards at three ecologically-relevant spatial scales, representing multiple flowers on a single plant, multiple plants within a locality, and multiple localities. Heliconius were able to learn spatial information at all three scales, consistent with this ability being an important component of their natural foraging behaviour.
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Affiliation(s)
- Priscila A Moura
- Departamento de Ecologia, Universidade Federal do Rio Grande do Norte, Natal, RN 59078-970, Brazil
| | - Fletcher J Young
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK; School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Monica Monllor
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Marcio Z Cardoso
- Departamento de Ecologia, Universidade Federal do Rio Grande do Norte, Natal, RN 59078-970, Brazil; Departamento de Ecologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil
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Young FJ, Monllor M, McMillan WO, Montgomery SH. Patterns of host plant use do not explain mushroom body expansion in Heliconiini butterflies. Proc Biol Sci 2023; 290:20231155. [PMID: 37491961 PMCID: PMC10369028 DOI: 10.1098/rspb.2023.1155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2023] Open
Abstract
The selective pressures leading to the elaboration of downstream, integrative processing centres, such as the mammalian neocortex or insect mushroom bodies, are often unclear. In Heliconius butterflies, the mushroom bodies are two to four times larger than those of their Heliconiini relatives, and the largest known in Lepidoptera. Heliconiini lay almost exclusively on Passiflora, which exhibit a remarkable diversity of leaf shape, and it has been suggested that the mushroom body expansion of Heliconius may have been driven by the cognitive demands of recognizing and learning leaf shapes of local host plants. We test this hypothesis using two complementary methods: (i) phylogenetic comparative analyses to test whether variation in mushroom body size is associated with the morphological diversity of host plants exploited across the Heliconiini; and (ii) shape-learning experiments using six Heliconiini species. We found that variation in the range of leaf morphologies used by Heliconiini was not associated with mushroom body volume. Similarly, we find interspecific differences in shape-learning ability, but Heliconius are not overall better shape learners than other Heliconiini. Together these results suggest that the visual recognition and learning of host plants was not a main factor driving the diversity of mushroom body size in this tribe.
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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
| | | | | | - 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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Couto A, Young FJ, Atzeni D, Marty S, Melo-Flórez L, Hebberecht L, Monllor M, Neal C, Cicconardi F, McMillan WO, Montgomery SH. Rapid expansion and visual specialisation of learning and memory centres in the brains of Heliconiini butterflies. Nat Commun 2023; 14:4024. [PMID: 37419890 PMCID: PMC10328955 DOI: 10.1038/s41467-023-39618-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 06/15/2023] [Indexed: 07/09/2023] Open
Abstract
Changes in the abundance and diversity of neural cell types, and their connectivity, shape brain composition and provide the substrate for behavioral evolution. Although investment in sensory brain regions is understood to be largely driven by the relative ecological importance of particular sensory modalities, how selective pressures impact the elaboration of integrative brain centers has been more difficult to pinpoint. Here, we provide evidence of extensive, mosaic expansion of an integration brain center among closely related species, which is not explained by changes in sites of primary sensory input. By building new datasets of neural traits among a tribe of diverse Neotropical butterflies, the Heliconiini, we detected several major evolutionary expansions of the mushroom bodies, central brain structures pivotal for insect learning and memory. The genus Heliconius, which exhibits a unique dietary innovation, pollen-feeding, and derived foraging behaviors reliant on spatial memory, shows the most extreme enlargement. This expansion is primarily associated with increased visual processing areas and coincides with increased precision of visual processing, and enhanced long term memory. These results demonstrate that selection for behavioral innovation and enhanced cognitive ability occurred through expansion and localized specialization in integrative brain centers.
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Affiliation(s)
- Antoine Couto
- School of Biological Sciences, University of Bristol, Bristol, UK
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Fletcher J Young
- School of Biological Sciences, University of Bristol, Bristol, UK
- Department of Zoology, University of Cambridge, Cambridge, UK
- Smithsonian Tropical Research Institute, Gamboa, Panama
| | - Daniele Atzeni
- School of Biological Sciences, University of Bristol, Bristol, UK
- Department of Life Science, University of Trieste, Trieste, Italy
| | - Simon Marty
- Department of Zoology, University of Cambridge, Cambridge, UK
- École Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Université de Lyon, Lyon, France
| | | | - Laura Hebberecht
- School of Biological Sciences, University of Bristol, Bristol, UK
- Department of Zoology, University of Cambridge, Cambridge, UK
- Smithsonian Tropical Research Institute, Gamboa, Panama
| | | | - Chris Neal
- Wolfson Bioimaging Facility, University of Bristol, Bristol, UK
| | | | | | - Stephen H Montgomery
- School of Biological Sciences, University of Bristol, Bristol, UK.
- Smithsonian Tropical Research Institute, Gamboa, Panama.
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Montejo-Kovacevich G, Martin SH, Meier JI, Bacquet CN, Monllor M, Jiggins CD, Nadeau NJ. Microclimate buffering and thermal tolerance across elevations in a tropical butterfly. J Exp Biol 2020; 223:jeb220426. [PMID: 32165433 PMCID: PMC7174841 DOI: 10.1242/jeb.220426] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 03/02/2020] [Indexed: 12/14/2022]
Abstract
Microclimatic variability in tropical forests plays a key role in shaping species distributions and their ability to cope with environmental change, especially for ectotherms. Nonetheless, currently available climatic datasets lack data from the forest interior and, furthermore, our knowledge of thermal tolerance among tropical ectotherms is limited. We therefore studied natural variation in the microclimate experienced by tropical butterflies in the genus Heliconius across their Andean range in a single year. We found that the forest strongly buffers temperature and humidity in the understorey, especially in the lowlands, where temperatures are more extreme. There were systematic differences between our yearly records and macroclimate databases (WorldClim2), with lower interpolated minimum temperatures and maximum temperatures higher than expected. We then assessed thermal tolerance of 10 Heliconius butterfly species in the wild and found that populations at high elevations had significantly lower heat tolerance than those at lower elevations. However, when we reared populations of the widespread H. erato from high and low elevations in a common-garden environment, the difference in heat tolerance across elevations was reduced, indicating plasticity in this trait. Microclimate buffering is not currently captured in publicly available datasets, but could be crucial for enabling upland shifting of species sensitive to heat such as highland Heliconius Plasticity in thermal tolerance may alleviate the effects of global warming on some widespread ectotherm species, but more research is needed to understand the long-term consequences of plasticity on populations and species.
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Affiliation(s)
| | - Simon H Martin
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
- Institute of Evolutionary Biology, The University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Joana I Meier
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
- St John's College, University of Cambridge, Cambridge CB2 3EJ, UK
| | | | - Monica Monllor
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Chris D Jiggins
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Nicola J Nadeau
- Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
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McClure M, Mahrouche L, Houssin C, Monllor M, Le Poul Y, Frérot B, Furtos A, Elias M. Does divergent selection predict the evolution of mate preference and reproductive isolation in the tropical butterfly genus
Melinaea
(Nymphalidae: Ithomiini)? J Anim Ecol 2019; 88:940-952. [DOI: 10.1111/1365-2656.12975] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 01/25/2019] [Indexed: 11/27/2022]
Affiliation(s)
- Melanie McClure
- Institut Systématique Évolution Biodiversité (ISYEB) Centre National de la Recherche Scientifique MNHN EPHE Sorbonne Université Université des Antilles Paris France
| | - Louiza Mahrouche
- Centre Régional de Spectrométrie de Masse Département de Chimie Université de Montréal Montréal Quebec Canada
| | - Céline Houssin
- Institut Systématique Évolution Biodiversité (ISYEB) Centre National de la Recherche Scientifique MNHN EPHE Sorbonne Université Université des Antilles Paris France
| | - Monica Monllor
- Institut Systématique Évolution Biodiversité (ISYEB) Centre National de la Recherche Scientifique MNHN EPHE Sorbonne Université Université des Antilles Paris France
| | - Yann Le Poul
- Faculty of Biology LMU Munich Planegg‐Martinsried Germany
| | - Brigitte Frérot
- Institut d’Écologie et des Sciences de l'Environnement IEES – INRA UMR 1392 Versailles Cedex France
| | - Alexandra Furtos
- Centre Régional de Spectrométrie de Masse Département de Chimie Université de Montréal Montréal Quebec Canada
| | - Marianne Elias
- Institut Systématique Évolution Biodiversité (ISYEB) Centre National de la Recherche Scientifique MNHN EPHE Sorbonne Université Université des Antilles Paris France
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