1
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Sondhi Y, Messcher RL, Bellantuono AJ, Storer CG, Cinel SD, Godfrey RK, Mongue AJ, Weng YM, Glass D, St Laurent RA, Hamilton CA, Earl C, Brislawn CJ, Kitching IJ, Bybee SM, Theobald JC, Kawahara AY. Day-night gene expression reveals circadian gene disco as a candidate for diel-niche evolution in moths. Proc Biol Sci 2024; 291:20240591. [PMID: 39194299 DOI: 10.1098/rspb.2024.0591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 07/08/2024] [Accepted: 07/09/2024] [Indexed: 08/29/2024] Open
Abstract
Temporal ecological niche partitioning is an underappreciated driver of speciation. While insects have long been models for circadian biology, the genes and circuits that allow adaptive changes in diel-niches remain poorly understood. We compared gene expression in closely related day- and night-active non-model wild silk moths, with otherwise similar ecologies. Using an ortholog-based pipeline to compare RNA-Seq patterns across two moth species, we find over 25 pairs of gene orthologs showing differential expression. Notably, the gene disco, involved in circadian control, optic lobe and clock neuron development in Drosophila, shows robust adult circadian mRNA cycling in moth heads. Disco is highly conserved in moths and has additional zinc-finger domains with specific nocturnal and diurnal mutations. We propose disco as a candidate gene for the diversification of temporal diel-niche in moths.
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Affiliation(s)
- Yash Sondhi
- McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida , Gainesville, FL 32611, USA
- Department of Biology, Florida International University , Miami, FL 33174, USA
- Institute for Environment, Florida International University , Miami, FL 33174, USA
| | - Rebeccah L Messcher
- McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida , Gainesville, FL 32611, USA
| | | | - Caroline G Storer
- McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida , Gainesville, FL 32611, USA
| | - Scott D Cinel
- McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida , Gainesville, FL 32611, USA
| | - R Keating Godfrey
- McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida , Gainesville, FL 32611, USA
- Department of Biology, Florida International University , Miami, FL 33174, USA
| | - Andrew J Mongue
- Department of Entomology and Nematology, University of Florida , Gainesville, FL 32611, USA
| | - Yi-Ming Weng
- McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida , Gainesville, FL 32611, USA
| | - Deborah Glass
- School of Life Sciences, University of Sussex, Sussex House , Brighton BN1 9RH, UK
- Natural History Museum, Cromwell Road , London SW7 5BD, UK
| | - Ryan A St Laurent
- McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida , Gainesville, FL 32611, USA
- Department of Entomology, Smithsonian Institution, National Museum of Natural History , Washington, DC, USA
| | - Chris A Hamilton
- Department of Entomology, Plant Pathology & Nematology, University of Idaho , Moscow, ID 83844, USA
| | - Chandra Earl
- McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida , Gainesville, FL 32611, USA
- Biodiversity Knowledge Integration Center, School of Life Sciences, Arizona State University , Tempe, AZ 852281, USA
| | | | - Ian J Kitching
- Natural History Museum, Cromwell Road , London SW7 5BD, UK
| | - Seth M Bybee
- Department of Biology, Monte L. Bean Museum, Brigham Young University, 4102 Life Science Building , Provo, UT 84602, USA
| | - Jamie C Theobald
- Department of Biology, Florida International University , Miami, FL 33174, USA
- Institute for Environment, Florida International University , Miami, FL 33174, USA
| | - Akito Y Kawahara
- McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida , Gainesville, FL 32611, USA
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2
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Wang Q, Smid HM, Dicke M, Haverkamp A. The olfactory system of Pieris brassicae caterpillars: from receptors to glomeruli. INSECT SCIENCE 2024; 31:469-488. [PMID: 38105530 DOI: 10.1111/1744-7917.13304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 10/17/2023] [Accepted: 10/30/2023] [Indexed: 12/19/2023]
Abstract
The olfactory system of adult lepidopterans is among the best described neuronal circuits. However, comparatively little is known about the organization of the olfactory system in the larval stage of these insects. Here, we explore the expression of olfactory receptors and the organization of olfactory sensory neurons in caterpillars of Pieris brassicae, a significant pest species in Europe and a well-studied species for its chemical ecology. To describe the larval olfactory system in this species, we first analyzed the head transcriptome of third-instar larvae (L3) and identified 16 odorant receptors (ORs) including the OR coreceptor (Orco), 13 ionotropic receptors (IRs), and 8 gustatory receptors (GRs). We then quantified the expression of these 16 ORs in different life stages, using qPCR, and found that the majority of ORs had significantly higher expression in the L4 stage than in the L3 and L5 stages, indicating that the larval olfactory system is not static throughout caterpillar development. Using an Orco-specific antibody, we identified all olfactory receptor neurons (ORNs) expressing the Orco protein in L3, L4, and L5 caterpillars and found a total of 34 Orco-positive ORNs, distributed among three sensilla on the antenna. The number of Orco-positive ORNs did not differ among the three larval instars. Finally, we used retrograde axon tracing of the antennal nerve and identified a mean of 15 glomeruli in the larval antennal center (LAC), suggesting that the caterpillar olfactory system follows a similar design as the adult olfactory system, although with a lower numerical redundancy. Taken together, our results provide a detailed analysis of the larval olfactory neurons in P. brassicae, highlighting both the differences as well as the commonalities with the adult olfactory system. These findings contribute to a better understanding of the development of the olfactory system in insects and its life-stage-specific adaptations.
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Affiliation(s)
- Qi Wang
- Laboratory of Entomology, Wageningen University and Research, Wageningen, the Netherlands
| | - Hans M Smid
- Laboratory of Entomology, Wageningen University and Research, Wageningen, the Netherlands
| | - Marcel Dicke
- Laboratory of Entomology, Wageningen University and Research, Wageningen, the Netherlands
| | - Alexander Haverkamp
- Laboratory of Entomology, Wageningen University and Research, Wageningen, the Netherlands
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3
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Page E, Queste LM, Rosser N, Salazar PA, Nadeau NJ, Mallet J, Srygley RB, McMillan WO, Dasmahapatra KK. Pervasive mimicry in flight behavior among aposematic butterflies. Proc Natl Acad Sci U S A 2024; 121:e2300886121. [PMID: 38408213 PMCID: PMC10945825 DOI: 10.1073/pnas.2300886121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 01/10/2024] [Indexed: 02/28/2024] Open
Abstract
Flight was a key innovation in the adaptive radiation of insects. However, it is a complex trait influenced by a large number of interacting biotic and abiotic factors, making it difficult to unravel the evolutionary drivers. We investigate flight patterns in neotropical heliconiine butterflies, well known for mimicry of their aposematic wing color patterns. We quantify the flight patterns (wing beat frequency and wing angles) of 351 individuals representing 29 heliconiine and 9 ithomiine species belonging to ten color pattern mimicry groupings. For wing beat frequency and up wing angles, we show that heliconiine species group by color pattern mimicry affiliation. Convergence of down wing angles to mimicry groupings is less pronounced, indicating that distinct components of flight are under different selection pressures and constraints. The flight characteristics of the Tiger mimicry group are particularly divergent due to convergence with distantly related ithomiine species. Predator-driven selection for mimicry also explained variation in flight among subspecies, indicating that this convergence can occur over relatively short evolutionary timescales. Our results suggest that the flight convergence is driven by aposematic signaling rather than shared habitat between comimics. We demonstrate that behavioral mimicry can occur between lineages that have separated over evolutionary timescales ranging from <0.5 to 70 My.
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Affiliation(s)
- Edward Page
- Department of Biology, University of York, HeslingtonYO10 5DD, United Kingdom
| | - Lucie M. Queste
- Department of Biology, University of York, HeslingtonYO10 5DD, United Kingdom
- Division of Evolutionary Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried82152, Germany
| | - Neil Rosser
- Department of Biology, University of York, HeslingtonYO10 5DD, United Kingdom
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA02138
| | - Patricio A. Salazar
- Ecology and Evolutionary Biology, School of Biosciences, The University of Sheffield, SheffieldS10 2TN, United Kingdom
- Tree of Life Programme, Wellcome Sanger Institute, Hinxton, CambridgeCB10 1SA, United Kingdom
| | - Nicola J. Nadeau
- Ecology and Evolutionary Biology, School of Biosciences, The University of Sheffield, SheffieldS10 2TN, United Kingdom
| | - James Mallet
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA02138
| | - Robert B. Srygley
- Smithsonian Tropical Research Institute, Apartado, Panamá0843-03092, Republic of Panama
- Pest Management Research Unit, Agricultural Research Service, United States Department of Agriculture, Sidney, MT59270
| | - W. Owen McMillan
- Smithsonian Tropical Research Institute, Apartado, Panamá0843-03092, Republic of Panama
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4
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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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5
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Konnerth MM, Foster JJ, el Jundi B, Spaethe J, Beetz MJ. Monarch butterflies memorize the spatial location of a food source. Proc Biol Sci 2023; 290:20231574. [PMID: 38113939 PMCID: PMC10730289 DOI: 10.1098/rspb.2023.1574] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 11/20/2023] [Indexed: 12/21/2023] Open
Abstract
Spatial memory helps animals to navigate familiar environments. In insects, spatial memory has extensively been studied in central place foragers such as ants and bees. However, if butterflies memorize a spatial location remains unclear. Here, we conducted behavioural experiments to test whether monarch butterflies (Danaus plexippus) can remember and retrieve the spatial location of a food source. We placed several visually identical feeders in a flight cage, with only one feeder providing sucrose solution. Across multiple days, individual butterflies predominantly visited the rewarding feeder. Next, we displaced a salient landmark close to the feeders to test which visual cue the butterflies used to relocate the rewarding feeder. While occasional landmark displacements were ignored by the butterflies and did not affect their decisions, systematic displacement of both the landmark and the rewarding feeder demonstrated that the butterflies associated the salient landmark with the feeder's position. Altogether, we show that butterflies consolidate and retrieve spatial memory in the context of foraging.
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Affiliation(s)
- M. Marcel Konnerth
- Zoology II, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Bayern, Germany
| | - James J. Foster
- Department of Biology, University of Konstanz, 78464 Konstanz, Baden-Württemberg, Germany
| | - Basil el Jundi
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Johannes Spaethe
- Zoology II, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Bayern, Germany
| | - M. Jerome Beetz
- Zoology II, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Bayern, Germany
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Wainwright JB, Schofield C, Conway M, Phillips D, Martin-Silverstone E, Brodrick EA, Cicconardi F, How MJ, Roberts NW, Montgomery SH. Multiple axes of visual system diversity in Ithomiini, an ecologically diverse tribe of mimetic butterflies. J Exp Biol 2023; 226:jeb246423. [PMID: 37921078 PMCID: PMC10714147 DOI: 10.1242/jeb.246423] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 10/31/2023] [Indexed: 11/04/2023]
Abstract
The striking structural variation seen in arthropod visual systems can be explained by the overall quantity and spatio-temporal structure of light within habitats coupled with developmental and physiological constraints. However, little is currently known about how fine-scale variation in visual structures arises across shorter evolutionary and ecological scales. In this study, we characterise patterns of interspecific (between species), intraspecific (between sexes) and intraindividual (between eye regions) variation in the visual system of four ithomiine butterfly species. These species are part of a diverse 26-million-year-old Neotropical radiation where changes in mimetic colouration are associated with fine-scale shifts in ecology, such as microhabitat preference. Using a combination of selection analyses on visual opsin sequences, in vivo ophthalmoscopy, micro-computed tomography (micro-CT), immunohistochemistry, confocal microscopy and neural tracing, we quantify and describe physiological, anatomical and molecular traits involved in visual processing. Using these data, we provide evidence of substantial variation within the visual systems of Ithomiini, including: (i) relaxed selection on visual opsins, perhaps mediated by habitat preference, (ii) interspecific shifts in visual system physiology and anatomy, and (iii) extensive sexual dimorphism, including the complete absence of a butterfly-specific optic neuropil in the males of some species. We conclude that considerable visual system variation can exist within diverse insect radiations, hinting at the evolutionary lability of these systems to rapidly develop specialisations to distinct visual ecologies, with selection acting at the perceptual, processing and molecular level.
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Affiliation(s)
- J. Benito Wainwright
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Corin Schofield
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Max Conway
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Daniel Phillips
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Elizabeth Martin-Silverstone
- Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Emelie A. Brodrick
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Francesco Cicconardi
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Martin J. How
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Nicholas W. Roberts
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Stephen H. Montgomery
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
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7
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Couto A, Marty S, Dawson EH, d'Ettorre P, Sandoz JC, Montgomery SH. Evolution of the neuronal substrate for kin recognition in social Hymenoptera. Biol Rev Camb Philos Soc 2023; 98:2226-2242. [PMID: 37528574 DOI: 10.1111/brv.13003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 07/18/2023] [Accepted: 07/20/2023] [Indexed: 08/03/2023]
Abstract
In evolutionary terms, life is about reproduction. Yet, in some species, individuals forgo their own reproduction to support the reproductive efforts of others. Social insect colonies for example, can contain up to a million workers that actively cooperate in tasks such as foraging, brood care and nest defence, but do not produce offspring. In such societies the division of labour is pronounced, and reproduction is restricted to just one or a few individuals, most notably the queen(s). This extreme eusocial organisation exists in only a few mammals, crustaceans and insects, but strikingly, it evolved independently up to nine times in the order Hymenoptera (including ants, bees and wasps). Transitions from a solitary lifestyle to an organised society can occur through natural selection when helpers obtain a fitness benefit from cooperating with kin, owing to the indirect transmission of genes through siblings. However, this process, called kin selection, is vulnerable to parasitism and opportunistic behaviours from unrelated individuals. An ability to distinguish kin from non-kin, and to respond accordingly, could therefore critically facilitate the evolution of eusociality and the maintenance of non-reproductive workers. The question of how the hymenopteran brain has adapted to support this function is therefore a fundamental issue in evolutionary neuroethology. Early neuroanatomical investigations proposed that social Hymenoptera have expanded integrative brain areas due to selection for increased cognitive capabilities in the context of processing social information. Later studies challenged this assumption and instead pointed to an intimate link between higher social organisation and the existence of developed sensory structures involved in recognition and communication. In particular, chemical signalling of social identity, known to be mediated through cuticular hydrocarbons (CHCs), may have evolved hand in hand with a specialised chemosensory system in Hymenoptera. Here, we compile the current knowledge on this recognition system, from emitted identity signals, to the molecular and neuronal basis of chemical detection, with particular emphasis on its evolutionary history. Finally, we ask whether the evolution of social behaviour in Hymenoptera could have driven the expansion of their complex olfactory system, or whether the early origin and conservation of an olfactory subsystem dedicated to social recognition could explain the abundance of eusocial species in this insect order. Answering this question will require further comparative studies to provide a comprehensive view on lineage-specific adaptations in the olfactory pathway of Hymenoptera.
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Affiliation(s)
- Antoine Couto
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
- Evolution, Genomes, Behaviour and Ecology (UMR 9191), IDEEV, Université Paris-Saclay, CNRS, IRD, 12 route 128, Gif-sur-Yvette, 91190, France
| | - Simon Marty
- Evolution, Genomes, Behaviour and Ecology (UMR 9191), IDEEV, Université Paris-Saclay, CNRS, IRD, 12 route 128, Gif-sur-Yvette, 91190, France
| | - Erika H Dawson
- Laboratory of Experimental and Comparative Ethology, UR 4443 (LEEC), Université Sorbonne Paris Nord, 99 avenue J.-B. Clément, Villetaneuse, 93430, France
| | - Patrizia d'Ettorre
- Laboratory of Experimental and Comparative Ethology, UR 4443 (LEEC), Université Sorbonne Paris Nord, 99 avenue J.-B. Clément, Villetaneuse, 93430, France
- Institut Universitaire de France (IUF), 103 Boulevard Saint-Michel, Paris, 75005, France
| | - Jean-Christophe Sandoz
- Evolution, Genomes, Behaviour and Ecology (UMR 9191), IDEEV, Université Paris-Saclay, CNRS, IRD, 12 route 128, Gif-sur-Yvette, 91190, France
| | - Stephen H Montgomery
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
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8
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Anton AA, Farnworth MS, Hebberecht L, Harrison CJ, Montgomery SH. A modified method to analyse cell proliferation using EdU labelling in large insect brains. PLoS One 2023; 18:e0292009. [PMID: 37796816 PMCID: PMC10553331 DOI: 10.1371/journal.pone.0292009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 09/11/2023] [Indexed: 10/07/2023] Open
Abstract
The study of neurogenesis is critical to understanding of the evolution of nervous systems. Within invertebrates, this process has been extensively studied in Drosophila melanogaster, which is the predominant model thanks to the availability of advanced genetic tools. However, insect nervous systems are extremely diverse, and by studying a range of taxa we can gain additional information about how nervous systems and their development evolve. One example of the high diversity of insect nervous system diversity is provided by the mushroom bodies. Mushroom bodies have critical roles in learning and memory and vary dramatically across species in relative size and the type(s) of sensory information they process. Heliconiini butterflies provide a useful snapshot of this diversity within a closely related clade. Within Heliconiini, the genus Heliconius contains species where mushroom bodies are 3-4 times larger than other closely related genera, relative to the rest of the brain. This variation in size is largely explained by increases in the number of Kenyon cells, the intrinsic neurons which form the mushroom body. Hence, variation in mushroom body size is the product of changes in cell proliferation during Kenyon cell neurogenesis. Studying this variation requires adapting labelling techniques for use in less commonly studied organisms, as methods developed for common laboratory insects often do not work. Here, we present a modified protocol for EdU staining to examine neurogenesis in large-brained insects, using Heliconiini butterflies as our primary case, but also demonstrating applicability to cockroaches, another large-brained insect.
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Affiliation(s)
- Amaia Alcalde Anton
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - Max S. Farnworth
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - Laura Hebberecht
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - C. Jill Harrison
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
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9
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Alcalde Anton A, Young FJ, Melo-Flórez L, Couto A, Cross S, McMillan WO, Montgomery SH. Adult neurogenesis does not explain the extensive post-eclosion growth of Heliconius mushroom bodies. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230755. [PMID: 37885989 PMCID: PMC10598442 DOI: 10.1098/rsos.230755] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 09/28/2023] [Indexed: 10/28/2023]
Abstract
Among butterflies, Heliconius have a unique behavioural profile, being the sole genus to actively feed on pollen. Heliconius learn the location of pollen resources, and have enhanced visual memories and expanded mushroom bodies, an insect learning and memory centre, relative to related genera. These structures also show extensive post-eclosion growth and developmental sensitivity to environmental conditions. However, whether this reflects plasticity in neurite growth, or an extension of neurogenesis into the adult stage, is unknown. Adult neurogenesis has been described in some Lepidoptera, and could provide one route to the increased neuron number observed in Heliconius. Here, we compare volumetric changes in the mushroom bodies of freshly eclosed and aged Heliconius erato and Dryas iulia, and estimate the number of intrinsic mushroom body neurons using a new and validated automated method to count nuclei. Despite extensive volumetric variation associated with age, our data show that neuron number is remarkably constant in both species, suggesting a lack of adult neurogenesis in the mushroom bodies. We support this conclusion with assays of mitotic cells, which reveal very low levels of post-eclosion cell division. Our analyses provide an insight into the evolution of neural plasticity, and can serve as a basis for continued exploration of the potential mechanisms behind brain development and maturation.
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Affiliation(s)
| | - Fletcher J. Young
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | | | - Antoine Couto
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Stephen Cross
- Wolfson Bioimaging Centre, University of Bristol, Bristol, UK
| | | | - Stephen H. Montgomery
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
- Smithsonian Tropical Research Institute, Gamboa, Panama
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10
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Cicconardi F, Milanetti E, Pinheiro de Castro EC, Mazo-Vargas A, Van Belleghem SM, Ruggieri AA, Rastas P, Hanly J, Evans E, Jiggins CD, Owen McMillan W, Papa R, Di Marino D, Martin A, Montgomery SH. Evolutionary dynamics of genome size and content during the adaptive radiation of Heliconiini butterflies. Nat Commun 2023; 14:5620. [PMID: 37699868 PMCID: PMC10497600 DOI: 10.1038/s41467-023-41412-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 08/30/2023] [Indexed: 09/14/2023] Open
Abstract
Heliconius butterflies, a speciose genus of Müllerian mimics, represent a classic example of an adaptive radiation that includes a range of derived dietary, life history, physiological and neural traits. However, key lineages within the genus, and across the broader Heliconiini tribe, lack genomic resources, limiting our understanding of how adaptive and neutral processes shaped genome evolution during their radiation. Here, we generate highly contiguous genome assemblies for nine Heliconiini, 29 additional reference-assembled genomes, and improve 10 existing assemblies. Altogether, we provide a dataset of annotated genomes for a total of 63 species, including 58 species within the Heliconiini tribe. We use this extensive dataset to generate a robust and dated heliconiine phylogeny, describe major patterns of introgression, explore the evolution of genome architecture, and the genomic basis of key innovations in this enigmatic group, including an assessment of the evolution of putative regulatory regions at the Heliconius stem. Our work illustrates how the increased resolution provided by such dense genomic sampling improves our power to generate and test gene-phenotype hypotheses, and precisely characterize how genomes evolve.
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Affiliation(s)
- Francesco Cicconardi
- School of Biological Sciences, Bristol University, Bristol, United Kingdom.
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom.
| | - Edoardo Milanetti
- Department of Physics, Sapienza University, Piazzale Aldo Moro 5, 00185, Rome, Italy
- Center for Life Nano- & Neuro-Science, Italian Institute of Technology, Viale Regina Elena 291, 00161, Rome, Italy
| | | | - Anyi Mazo-Vargas
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Steven M Van Belleghem
- Department of Biology, University of Puerto Rico, Rio Piedras, PR, Puerto Rico
- Ecology, Evolution and Conservation Biology, Biology Department, KU Leuven, Leuven, Belgium
| | | | - Pasi Rastas
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Joseph Hanly
- Department of Biological Sciences, The George Washington University, Washington DC, WA, 20052, USA
- Smithsonian Tropical Research Institute, Panama City, Panama
| | - Elizabeth Evans
- Department of Biology, University of Puerto Rico, Rio Piedras, PR, Puerto Rico
| | - Chris D Jiggins
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - W Owen McMillan
- Smithsonian Tropical Research Institute, Panama City, Panama
| | - Riccardo Papa
- Department of Biology, University of Puerto Rico, Rio Piedras, PR, Puerto Rico
- Molecular Sciences and Research Center, University of Puerto Rico, San Juan, PR, Puerto Rico
- Comprehensive Cancer Center, University of Puerto Rico, San Juan, PR, Puerto Rico
| | - Daniele Di Marino
- Department of Life and Environmental Sciences, New York-Marche Structural Biology Center (NY-MaSBiC), Polytechnic University of Marche, Via Brecce Bianche, 60131, Ancona, Italy
- Neuronal Death and Neuroprotection Unit, Department of Neuroscience, Mario Negri Institute for Pharmacological Research-IRCCS, Via Mario Negri 2, 20156, Milano, Italy
- National Biodiversity Future Center (NBFC), Palermo, Italy
| | - Arnaud Martin
- Department of Biological Sciences, The George Washington University, Washington DC, WA, 20052, USA
| | - Stephen H Montgomery
- School of Biological Sciences, Bristol University, Bristol, United Kingdom.
- Smithsonian Tropical Research Institute, Panama City, Panama.
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11
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Sehadová H, Podlahová Š, Reppert SM, Sauman I. 3D reconstruction of larval and adult brain neuropils of two giant silk moth species: Hyalophora cecropia and Antheraea pernyi. JOURNAL OF INSECT PHYSIOLOGY 2023; 149:104546. [PMID: 37451537 DOI: 10.1016/j.jinsphys.2023.104546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 06/21/2023] [Accepted: 07/07/2023] [Indexed: 07/18/2023]
Abstract
We present a detailed analysis of the brain anatomy of two saturniid species, the cecropia silk moth, Hyalophora cecropia, and the Chinese oak silk moth, Antheraea pernyi, including 3D reconstructions of the major brain neuropils in the larva and in male and female adults. The 3D reconstructions, prepared from high-resolution optical sections, showed that the corresponding neuropils of these saturniid species are virtually identical. Similarities between the two species include a pronounced sexual dimorphism in the adults in the form of a male-specific assembly of markedly enlarged glomeruli forming the so-called macroglomerular complex. From the reports published to date, it can be concluded that the neuropil architecture of saturniids resembles that of other nocturnal moths, including the sibling family Sphingidae. In addition, compared with previous anatomical data on diurnal lepidopteran species, significant differences were observed in the two saturniid species, which include the thickness of the Y-tract of the mushroom body, the size of the main neuropils of the optic lobes, and the sexual dimorphisms of the antennal lobes.
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Affiliation(s)
- Hana Sehadová
- Biology Centre CAS, Institute of Entomology, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic; University of South Bohemia in Ceske Budejovice, Faculty of Science, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic.
| | - Šárka Podlahová
- Biology Centre CAS, Institute of Entomology, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic; University of South Bohemia in Ceske Budejovice, Faculty of Science, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic.
| | - Steven M Reppert
- Department of Neurobiology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA.
| | - Ivo Sauman
- Biology Centre CAS, Institute of Entomology, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic; University of South Bohemia in Ceske Budejovice, Faculty of Science, Branisovska 31, 370 05 Ceske Budejovice, Czech Republic.
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12
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Hebberecht L, Wainwright JB, Thompson C, Kershenbaum S, McMillan WO, Montgomery SH. Plasticity and genetic effects contribute to different axes of neural divergence in a community of mimetic Heliconius butterflies. J Evol Biol 2023; 36:1116-1132. [PMID: 37341138 DOI: 10.1111/jeb.14188] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 03/12/2023] [Accepted: 04/16/2023] [Indexed: 06/22/2023]
Abstract
Changes in ecological preference, often driven by spatial and temporal variation in resource distribution, can expose populations to environments with divergent information content. This can lead to adaptive changes in the degree to which individuals invest in sensory systems and downstream processes, to optimize behavioural performance in different contexts. At the same time, environmental conditions can produce plastic responses in nervous system development and maturation, providing an alternative route to integrating neural and ecological variation. Here, we explore how these two processes play out across a community of Heliconius butterflies. Heliconius communities exhibit multiple Mullerian mimicry rings, associated with habitat partitioning across environmental gradients. These environmental differences have previously been linked to heritable divergence in brain morphology in parapatric species pairs. They also exhibit a unique dietary adaptation, known as pollen feeding, that relies heavily on learning foraging routes, or trap-lines, between resources, which implies an important environmental influence on behavioural development. By comparing brain morphology across 133 wild-caught and insectary-reared individuals from seven Heliconius species, we find strong evidence for interspecific variation in patterns of neural investment. These largely fall into two distinct patterns of variation; first, we find consistent patterns of divergence in the size of visual brain components across both wild and insectary-reared individuals, suggesting genetically encoded divergence in the visual pathway. Second, we find interspecific differences in mushroom body size, a central component of learning and memory systems, but only among wild caught individuals. The lack of this effect in common-garden individuals suggests an extensive role for developmental plasticity in interspecific variation in the wild. Finally, we illustrate the impact of relatively small-scale spatial effects on mushroom body plasticity by performing experiments altering the cage size and structure experienced by individual H. hecale. Our data provide a comprehensive survey of community level variation in brain structure, and demonstrate that genetic effects and developmental plasticity contribute to different axes of interspecific neural variation.
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Affiliation(s)
- 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
| | | | | | | | | | - Stephen H Montgomery
- School of Biological Sciences, University of Bristol, Bristol, UK
- Smithsonian Tropical Research Institute, Gamboa, Panama
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13
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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: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [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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14
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Borrero J, Wright DS, Bacquet CN, Merrill RM. Oviposition behavior is not affected by ultraviolet light in a butterfly with sexually-dimorphic expression of a UV-sensitive opsin. Ecol Evol 2023; 13:e10243. [PMID: 37408633 PMCID: PMC10318619 DOI: 10.1002/ece3.10243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2023] [Revised: 06/09/2023] [Accepted: 06/14/2023] [Indexed: 07/07/2023] Open
Abstract
Animal vision is important for mediating multiple complex behaviors. In Heliconius butterflies, vision guides fundamental behaviors such as oviposition, foraging, and mate choice. Color vision in Heliconius involves ultraviolet (UV), blue and long-wavelength-sensitive photoreceptors (opsins). Additionally, Heliconius possess a duplicated UV opsin, and its expression varies widely within the genus. In Heliconius erato, opsin expression is sexually dimorphic; only females express both UV-sensitive opsins, enabling UV wavelength discrimination. However, the selective pressures responsible for sex-specific differences in opsin expression and visual perception remain unresolved. Female Heliconius invest heavily in finding suitable hostplants for oviposition, a behavior heavily dependent on visual cues. Here, we tested the hypothesis that UV vision is important for oviposition in H. erato and Heliconius himera females by manipulating the availability of UV in behavioral experiments under natural conditions. Our results indicate that UV does not influence the number of oviposition attempts or eggs laid, and the hostplant, Passiflora punctata, does not reflect UV wavelengths. Models of H. erato female vision suggest only minimal stimulation of the UV opsins. Overall, these findings suggest that UV wavelengths do not directly affect the ability of Heliconius females to find suitable oviposition sites. Alternatively, UV discrimination could be used in the context of foraging or mate choice, but this remains to be tested.
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Affiliation(s)
- Jose Borrero
- Division of Evolutionary BiologyLMU MunichMunichGermany
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15
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Fabian B, Sachse S. Experience-dependent plasticity in the olfactory system of Drosophila melanogaster and other insects. Front Cell Neurosci 2023; 17:1130091. [PMID: 36923450 PMCID: PMC10010147 DOI: 10.3389/fncel.2023.1130091] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 02/07/2023] [Indexed: 02/24/2023] Open
Abstract
It is long known that the nervous system of vertebrates can be shaped by internal and external factors. On the other hand, the nervous system of insects was long assumed to be stereotypic, although evidence for plasticity effects accumulated for several decades. To cover the topic comprehensively, this review recapitulates the establishment of the term "plasticity" in neuroscience and introduces its original meaning. We describe the basic composition of the insect olfactory system using Drosophila melanogaster as a representative example and outline experience-dependent plasticity effects observed in this part of the brain in a variety of insects, including hymenopterans, lepidopterans, locusts, and flies. In particular, we highlight recent advances in the study of experience-dependent plasticity effects in the olfactory system of D. melanogaster, as it is the most accessible olfactory system of all insect species due to the genetic tools available. The partly contradictory results demonstrate that morphological, physiological and behavioral changes in response to long-term olfactory stimulation are more complex than previously thought. Different molecular mechanisms leading to these changes were unveiled in the past and are likely responsible for this complexity. We discuss common problems in the study of experience-dependent plasticity, ways to overcome them, and future directions in this area of research. In addition, we critically examine the transferability of laboratory data to natural systems to address the topic as holistically as possible. As a mechanism that allows organisms to adapt to new environmental conditions, experience-dependent plasticity contributes to an animal's resilience and is therefore a crucial topic for future research, especially in an era of rapid environmental changes.
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Affiliation(s)
| | - Silke Sachse
- Research Group Olfactory Coding, Max Planck Institute for Chemical Ecology, Jena, Germany
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16
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Wainwright JB, Montgomery SH. Neuroanatomical shifts mirror patterns of ecological divergence in three diverse clades of mimetic butterflies. Evolution 2022; 76:1806-1820. [PMID: 35767896 PMCID: PMC9540801 DOI: 10.1111/evo.14547] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 05/30/2022] [Accepted: 06/06/2022] [Indexed: 01/22/2023]
Abstract
Microhabitat partitioning in heterogenous environments can support more diverse communities but may expose partitioned species to distinct perceptual challenges. Divergence across microhabitats could therefore lead to local adaptation to contrasting sensory conditions across small spatial scales, but this aspect of community structuring is rarely explored. Diverse communities of ithomiine butterflies provide an example where closely related species partition tropical forests, where shifts in mimetic coloration are tightly associated with shifts in habitat preference. We test the hypothesis that these mimetic and ecological shifts are associated with distinct patterns of sensory neural investment by comparing brain structure across 164 individuals of 16 species from three ithomiine clades. We find distinct brain morphologies between Oleriina and Hypothyris, which are mimetically homogenous and occupy a single microhabitat. Oleriina, which occurs in low-light microhabitats, invests less in visual brain regions than Hypothyris, with one notable exception, Hyposcada anchiala, the only Oleriina sampled to have converged on mimicry rings found in Hypothyris. We also find that Napeogenes, which has diversified into a range of mimicry rings, shows intermediate patterns of sensory investment. We identify flight height as a critical factor shaping neuroanatomical diversity, with species that fly higher in the canopy investing more in visual structures. Our work suggests that the sensory ecology of species may be impacted by, and interact with, the ways in which communities of closely related organisms are adaptively assembled.
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17
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Jaumann S, Rehan SM, Schwartz K, Smith AR. Reduced neural investment in post-reproductive females of the bee Ceratina calcarta. Sci Rep 2022; 12:8256. [PMID: 35585164 PMCID: PMC9117229 DOI: 10.1038/s41598-022-12281-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 04/27/2022] [Indexed: 11/09/2022] Open
Abstract
Many insects show plasticity in the area of the brain called the mushroom bodies (MB) with foraging and social experience. MBs are paired neuropils associated with learning and memory. MB volume is typically greater in mature foragers relative to young and/or inexperienced individuals. Long-term studies show that extended experience may further increase MB volume, but long-term studies have only been performed on non-reproductive social insect workers. Here we use the subsocial bee Ceratina calcarata to test the effect of extended foraging experience on MB volume among reproductive females. Ceratina calcarata females forage to provision their immature offspring in the spring, and then again to provision their adult daughters in the late summer. We measured the volume of the MB calyces and peduncle, antennal lobes (AL), optic lobes (OL), central complex (CX), and whole brains of three groups of bees: newly emerged females, reproductive females in spring (foundresses), and post-reproductive mothers feeding their adult daughters in late summer. Post-reproductive late summer mothers had smaller MB calyces and ALs than foundresses. Moreover, among late mothers (but not other bees), wing wear, which is a measure of foraging experience, negatively correlated with both MB and OL volume. This is contrary to previously studied non-reproductive social insect workers in which foraging experience correlates postiviely with MB volume, and suggests that post-reproductive bees may reduce neural investment near the end of their lives.
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Affiliation(s)
- Sarah Jaumann
- Department of Biological Sciences, George Washington University, 800 22nd St. NW, Washington, DC, 20052, USA
| | - Sandra M Rehan
- Department of Biology, York University, Toronto, ON, Canada
| | - Kayla Schwartz
- Department of Biological Sciences, George Washington University, 800 22nd St. NW, Washington, DC, 20052, USA
| | - Adam R Smith
- Department of Biological Sciences, George Washington University, 800 22nd St. NW, Washington, DC, 20052, USA.
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18
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Rather PA, Herzog AE, Ernst DA, Westerman EL. Effect of experience on mating behaviour in male Heliconius melpomene butterflies. Anim Behav 2022. [DOI: 10.1016/j.anbehav.2021.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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19
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Moura PA, Corso G, Montgomery SH, Cardoso MZ. True site fidelity in pollen‐feeding butterflies. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13976] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Priscila A. Moura
- Departamento de Ecologia Universidade Federal do Rio Grande do Norte Natal Brazil
| | - Giberto Corso
- Departamento de Biofísica e Farmacologia Universidade Federal do Rio Grande do Norte Natal Brazil
| | | | - Marcio Z. Cardoso
- Departamento de Ecologia Universidade Federal do Rio Grande do Norte Natal Brazil
- Departamento de Ecologia Instituto de Biologia Universidade Federal do Rio de Janeiro Rio de Janeiro Brazil
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20
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Hagadorn MA, Eck K, Del Grosso M, Haemmerle X, Wcislo WT, Kapheim KM. Age-related mushroom body expansion in male sweat bees and bumble bees. Sci Rep 2021; 11:17039. [PMID: 34426595 PMCID: PMC8382693 DOI: 10.1038/s41598-021-96268-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 08/04/2021] [Indexed: 01/20/2023] Open
Abstract
A well-documented phenomenon among social insects is that brain changes occur prior to or at the onset of certain experiences, potentially serving to prime the brain for specific tasks. This insight comes almost exclusively from studies considering developmental maturation in females. As a result, it is unclear whether age-related brain plasticity is consistent across sexes, and to what extent developmental patterns differ. Using confocal microscopy and volumetric analyses, we investigated age-related brain changes coinciding with sexual maturation in the males of the facultatively eusocial sweat bee, Megalopta genalis, and the obligately eusocial bumble bee, Bombus impatiens. We compared volumetric measurements between newly eclosed and reproductively mature males kept isolated in the lab. We found expansion of the mushroom bodies-brain regions associated with learning and memory-with maturation, which were consistent across both species. This age-related plasticity may, therefore, play a functionally-relevant role in preparing male bees for mating, and suggests that developmentally-driven neural restructuring can occur in males, even in species where it is absent in females.
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Affiliation(s)
- Mallory A Hagadorn
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT, 84322, USA.
| | - Karlee Eck
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT, 84322, USA
| | - Matthew Del Grosso
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT, 84322, USA
| | - Xavier Haemmerle
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT, 84322, USA
| | - William T Wcislo
- Smithsonian Tropical Research Institute, 0843-03092, Panama City, Republic of Panama
| | - Karen M Kapheim
- Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT, 84322, USA.
- Smithsonian Tropical Research Institute, 0843-03092, Panama City, Republic of Panama.
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21
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Morris BJ, Couto A, Aydin A, Montgomery SH. Re-emergence and diversification of a specialized antennal lobe morphology in ithomiine butterflies. Evolution 2021; 75:3191-3202. [PMID: 34383301 DOI: 10.1111/evo.14324] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 07/15/2021] [Accepted: 08/02/2021] [Indexed: 11/29/2022]
Abstract
How an organism's sensory system functions is central to how it navigates its environment. The insect olfactory system is a prominent model for investigating how ecological factors impact sensory reception and processing. Notably, work in Lepidoptera led to the discovery of vastly expanded structures, termed macroglomerular complexes (MGCs), within the primary olfactory processing centre. MGCs typically process pheromonal cues, are usually larger in males, and provide classic examples of how variation in the size of neural structures reflects the importance of sensory cues. Though prevalent across moths, MGCs were lost during the origin of butterflies, consistent with evidence that courtship initiation in butterflies is primarily reliant on visual cues, rather than long distance chemical signals. However, an MGC was recently described in a species of ithomiine butterfly, suggesting that this once lost neural adaptation has re-emerged in this tribe. Here, we show that MGC-like morphologies are widely distributed across ithomiines, but vary in both their structure and prevalence of sexual dimorphism. Based on this interspecific variation we suggest that the ithomiine MGC is involved in processing both plant and pheromonal cues, which have similarities in their chemical constitution, and co-evolved with an increased importance of plant derived chemical compounds.
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Affiliation(s)
- Billy J Morris
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Antoine Couto
- Department of Zoology, University of Cambridge, Cambridge, UK.,School of Biological Sciences, University of Bristol, Bristol, UK
| | - Asli Aydin
- School of Medicine, Koc University, Rumelifeneri Yolu, Istanbul, Turkey
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22
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Toh YP, Dion E, Monteiro A. Dissections of Larval, Pupal and Adult Butterfly Brains for Immunostaining and Molecular Analysis. Methods Protoc 2021; 4:53. [PMID: 34449688 PMCID: PMC8395752 DOI: 10.3390/mps4030053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 07/28/2021] [Accepted: 07/31/2021] [Indexed: 11/21/2022] Open
Abstract
Butterflies possess impressive cognitive abilities, and investigations into the neural mechanisms underlying these abilities are increasingly being conducted. Exploring butterfly neurobiology may require the isolation of larval, pupal, and/or adult brains for further molecular and histological experiments. This procedure has been largely described in the fruit fly, but a detailed description of butterfly brain dissections is still lacking. Here, we provide a detailed written and video protocol for the removal of Bicyclus anynana adult, pupal, and larval brains. This species is gradually becoming a popular model because it uses a large set of sensory modalities, displays plastic and hormonally controlled courtship behaviour, and learns visual mate preference and olfactory preferences that can be passed on to its offspring. The extracted brain can be used for downstream analyses, such as immunostaining, DNA or RNA extraction, and the procedure can be easily adapted to other lepidopteran species and life stages.
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Affiliation(s)
- Yi Peng Toh
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; (Y.P.T.); (A.M.)
| | - Emilie Dion
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; (Y.P.T.); (A.M.)
| | - Antónia Monteiro
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore; (Y.P.T.); (A.M.)
- Yale-NUS College, 10 College Avenue West, Singapore 138609, Singapore
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23
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Neural divergence and hybrid disruption between ecologically isolated Heliconius butterflies. Proc Natl Acad Sci U S A 2021; 118:2015102118. [PMID: 33547240 DOI: 10.1073/pnas.2015102118] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The importance of behavioral evolution during speciation is well established, but we know little about how this is manifest in sensory and neural systems. A handful of studies have linked specific neural changes to divergence in host or mate preferences associated with speciation. However, the degree to which brains are adapted to local environmental conditions, and whether this contributes to reproductive isolation between close relatives that have diverged in ecology, remains unknown. Here, we examine divergence in brain morphology and neural gene expression between closely related, but ecologically distinct, Heliconius butterflies. Despite ongoing gene flow, sympatric species pairs within the melpomene-cydno complex are consistently separated across a gradient of open to closed forest and decreasing light intensity. By generating quantitative neuroanatomical data for 107 butterflies, we show that Heliconius melpomene and Heliconius cydno clades have substantial shifts in brain morphology across their geographic range, with divergent structures clustered in the visual system. These neuroanatomical differences are mirrored by extensive divergence in neural gene expression. Differences in both neural morphology and gene expression are heritable, exceed expected rates of neutral divergence, and result in intermediate traits in first-generation hybrid offspring. Strong evidence of divergent selection implies local adaptation to distinct selective optima in each parental microhabitat, suggesting the intermediate traits of hybrids are poorly matched to either condition. Neural traits may therefore contribute to coincident barriers to gene flow, thereby helping to facilitate speciation.
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24
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Strausfeld N, Sayre ME. Shore crabs reveal novel evolutionary attributes of the mushroom body. eLife 2021; 10:65167. [PMID: 33559601 PMCID: PMC7872517 DOI: 10.7554/elife.65167] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 01/14/2021] [Indexed: 11/13/2022] Open
Abstract
Neural organization of mushroom bodies is largely consistent across insects, whereas the ancestral ground pattern diverges broadly across crustacean lineages resulting in successive loss of columns and the acquisition of domed centers retaining ancestral Hebbian-like networks and aminergic connections. We demonstrate here a major departure from this evolutionary trend in Brachyura, the most recent malacostracan lineage. In the shore crab Hemigrapsus nudus, instead of occupying the rostral surface of the lateral protocerebrum, mushroom body calyces are buried deep within it with their columns extending outwards to an expansive system of gyri on the brain’s surface. The organization amongst mushroom body neurons reaches extreme elaboration throughout its constituent neuropils. The calyces, columns, and especially the gyri show DC0 immunoreactivity, an indicator of extensive circuits involved in learning and memory.
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Affiliation(s)
| | - Marcel E Sayre
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden.,Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
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25
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Polilov AA, Makarova AA. Constant neuropilar ratio in the insect brain. Sci Rep 2020; 10:21426. [PMID: 33293636 PMCID: PMC7722839 DOI: 10.1038/s41598-020-78599-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 11/27/2020] [Indexed: 01/10/2023] Open
Abstract
Revealing scaling rules is necessary for understanding the morphology, physiology and evolution of living systems. Studies of animal brains have revealed both general patterns, such as Haller's rule, and patterns specific for certain animal taxa. However, large-scale studies aimed at studying the ratio of the entire neuropil and the cell body rind in the insect brain have never been performed. Here we performed morphometric study of the adult brain in 37 insect species of 26 families and ten orders, ranging in volume from the smallest to the largest by a factor of more than 4,000,000, and show that all studied insects display a similar ratio of the volume of the neuropil to the cell body rind, 3:2. Allometric analysis for all insects shows that the ratio of the volume of the neuropil to the volume of the brain changes strictly isometrically. Analyses within particular taxa, size groups, and metamorphosis types also reveal no significant differences in the relative volume of the neuropil; isometry is observed in all cases. Thus, we establish a new scaling rule, according to which the relative volume of the entire neuropil in insect brain averages 60% and remains constant.
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Affiliation(s)
- Alexey A Polilov
- Department of Entomology, Biological Faculty, Lomonosov Moscow State University, 119234, Moscow, Russia.
| | - Anastasia A Makarova
- Department of Entomology, Biological Faculty, Lomonosov Moscow State University, 119234, Moscow, Russia
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Couto A, Wainwright JB, Morris BJ, Montgomery SH. Linking ecological specialisation to adaptations in butterfly brains and sensory systems. CURRENT OPINION IN INSECT SCIENCE 2020; 42:55-60. [PMID: 32979531 DOI: 10.1016/j.cois.2020.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 07/27/2020] [Accepted: 09/07/2020] [Indexed: 06/11/2023]
Abstract
Butterflies display incredible ecological and behavioural diversity. As such, they have been subject to intense study since the birth of evolutionary biology. However, with some possible exceptions, they are underused models in comparative and functional neurobiology. We highlight a series of areas, spanning sensory ecology to cognition, in which butterflies are particularly promising systems for investigating the neurobiological basis for behavioural or ecological variation. These fields benefit from a history of molecular and quantitative genetics, and basic comparative neuroanatomy, but these strands of research are yet to be widely integrated. We discuss areas for potential growth and argue that new experimental techniques, growing genomic resources, and tools for functional genetics will accelerate the use of butterflies in neurobiology.
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Affiliation(s)
- Antoine Couto
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - J Benito Wainwright
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Billy J Morris
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
| | - Stephen H Montgomery
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK.
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27
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Eriksson M, Janz N, Nylin S, Carlsson MA. Structural plasticity of olfactory neuropils in relation to insect diapause. Ecol Evol 2020; 10:14423-14434. [PMID: 33391725 PMCID: PMC7771155 DOI: 10.1002/ece3.7046] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 10/19/2020] [Accepted: 10/23/2020] [Indexed: 12/14/2022] Open
Abstract
Many insects that live in temperate zones spend the cold season in a state of dormancy, referred to as diapause. As the insect must rely on resources that were gathered before entering diapause, keeping a low metabolic rate is of utmost importance. Organs that are metabolically expensive to maintain, such as the brain, can therefore become a liability to survival if they are too large.Insects that go through diapause as adults generally do so before entering the season of reproduction. This order of events introduces a conflict between maintaining low metabolism during dormancy and emerging afterward with highly developed sensory systems that improve fitness during the mating season.We investigated the timing of when investments into the olfactory system are made by measuring the volumes of primary and secondary olfactory neuropils in the brain as they fluctuate in size throughout the extended diapause life-period of adult Polygonia c-album butterflies.Relative volumes of both olfactory neuropils increase significantly during early adult development, indicating the importance of olfaction to this species, but still remain considerably smaller than those of nondiapausing conspecifics. However, despite butterflies being kept under the same conditions as before the dormancy, their olfactory neuropil volumes decreased significantly during the postdormancy period.The opposing directions of change in relative neuropil volumes before and after diapause dormancy indicate that the investment strategies governing structural plasticity during the two life stages could be functionally distinct. As butterflies were kept in stimulus-poor conditions, we find it likely that investments into these brain regions rely on experience-expectant processes before diapause and experience-dependent processes after diapause conditions are broken.As the shift in investment strategies coincides with a hard shift from premating season to mating season, we argue that these developmental characteristics could be adaptations that mitigate the trade-off between dormancy survival and reproductive fitness.
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Affiliation(s)
| | - Niklas Janz
- Department of ZoologyStockholm UniversityStockholmSweden
| | - Sören Nylin
- Department of ZoologyStockholm UniversityStockholmSweden
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28
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Young FJ, Montgomery SH. Pollen feeding in Heliconius butterflies: the singular evolution of an adaptive suite. Proc Biol Sci 2020; 287:20201304. [PMID: 33171092 PMCID: PMC7735275 DOI: 10.1098/rspb.2020.1304] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 10/15/2020] [Indexed: 12/21/2022] Open
Abstract
Major evolutionary transitions can be triggered by behavioural novelty, and are often associated with 'adaptive suites', which involve shifts in multiple co-adapted traits subject to complex interactions. Heliconius butterflies represent one such example, actively feeding on pollen, a behaviour unique among butterflies. Pollen feeding permits a prolonged reproductive lifespan, and co-occurs with a constellation of behavioural, neuroanatomical, life history, morphological and physiological traits that are absent in closely related, non-pollen-feeding genera. As a highly tractable system, supported by considerable ecological and genomic data, Heliconius are an excellent model for investigating how behavioural innovation can trigger a cascade of adaptive shifts in multiple diverse, but interrelated, traits. Here, we synthesize current knowledge of pollen feeding in Heliconius, and explore potential interactions between associated, putatively adaptive, traits. Currently, no physiological, morphological or molecular innovation has been explicitly linked to the origin of pollen feeding, and several hypothesized links between different aspects of Heliconius biology remain poorly tested. However, resolving these uncertainties will contribute to our understanding of how behavioural innovations evolve and subsequently alter the evolutionary trajectories of diverse traits impacting resource acquisition, life history, senescence and cognition.
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Affiliation(s)
- Fletcher J. Young
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- School of Biological Science, University of Bristol, 24 Tyndall Avenue, Bristol UBS8 1TQ, UK
| | - Stephen H. Montgomery
- School of Biological Science, University of Bristol, 24 Tyndall Avenue, Bristol UBS8 1TQ, UK
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29
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Toure MW, Young FJ, McMillan WO, Montgomery SH. Heliconiini butterflies can learn time-dependent reward associations. Biol Lett 2020; 16:20200424. [PMID: 32961092 PMCID: PMC7532716 DOI: 10.1098/rsbl.2020.0424] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
For many pollinators, flowers provide predictable temporal schedules of resource availability, meaning an ability to learn time-dependent information could be widely beneficial. However, this ability has only been demonstrated in a handful of species. Observations of Heliconius butterflies suggest that they may have an ability to form time-dependent foraging preferences. Heliconius are unique among butterflies in actively collecting pollen, a dietary behaviour linked to spatio-temporally faithful ‘trap-line' foraging. Time dependency of foraging preferences is hypothesized to allow Heliconius to exploit temporal predictability in alternative pollen resources. Here, we provide the first experimental evidence in support of this hypothesis, demonstrating that Heliconius hecale can learn opposing colour preferences in two time periods. This shift in preference is robust to the order of presentation, suggesting that preference is tied to the time of day and not due to ordinal or interval learning. However, this ability is not limited to Heliconius, as previously hypothesized, but also present in a related genus of non-pollen feeding butterflies. This demonstrates time learning likely pre-dates the origin of pollen feeding and may be prevalent across butterflies with less specialized foraging behaviours.
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Affiliation(s)
- M Wyatt Toure
- Department of Biology, McGill University, 1205 Docteur Penfield, Montreal, Canada H3A 1B1.,Smithsonian Tropical Research Institute, Gamboa, Panama
| | - Fletcher J Young
- Smithsonian Tropical Research Institute, Gamboa, Panama.,Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK.,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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30
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Snell‐Rood EC, Swanson EM, Espeset A, Jaumann S, Philips K, Walker C, Semke B, Mori AS, Boenisch G, Kattge J, Seabloom EW, Borer ET. Nutritional constraints on brain evolution: Sodium and nitrogen limit brain size. Evolution 2020; 74:2304-2319. [DOI: 10.1111/evo.14072] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 07/07/2020] [Accepted: 07/25/2020] [Indexed: 12/30/2022]
Affiliation(s)
- Emilie C. Snell‐Rood
- Department of Ecology, Evolution and Behavior University of Minnesota Minneapolis Minnesota 55455
| | - Eli M. Swanson
- Department of Ecology, Evolution and Behavior University of Minnesota Minneapolis Minnesota 55455
| | - Anne Espeset
- Department of Ecology, Evolution and Behavior University of Minnesota Minneapolis Minnesota 55455
- Department of Biology University of Nevada‐Reno Reno Nevada 89557
| | - Sarah Jaumann
- Department of Ecology, Evolution and Behavior University of Minnesota Minneapolis Minnesota 55455
- Department of Biological Sciences George Washington University Washington District of Columbia 20052
| | - Kinsey Philips
- Department of Ecology, Evolution and Behavior University of Minnesota Minneapolis Minnesota 55455
| | - Courtney Walker
- Department of Ecology, Evolution and Behavior University of Minnesota Minneapolis Minnesota 55455
| | - Brandon Semke
- Department of Ecology, Evolution and Behavior University of Minnesota Minneapolis Minnesota 55455
| | - Akira S. Mori
- Graduate School of Environment and Information Sciences Yokohama National University Yokohama Japan
| | | | - Jens Kattge
- Max‐Planck‐Institute for Biogeochemistry Jena Germany
| | - Eric W. Seabloom
- Department of Ecology, Evolution and Behavior University of Minnesota Minneapolis Minnesota 55455
| | - Elizabeth T. Borer
- Department of Ecology, Evolution and Behavior University of Minnesota Minneapolis Minnesota 55455
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31
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Fujiki K, Nagase M, Takaki K, Watanabe H, Yamawaki Y. Three-dimensional atlas of thoracic ganglia in the praying mantis, Tenodera aridifolia. J Comp Neurol 2020; 528:1599-1615. [PMID: 31846077 DOI: 10.1002/cne.24841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 12/12/2019] [Accepted: 12/13/2019] [Indexed: 11/06/2022]
Abstract
The praying mantis is a good model for the study of motor control, especially for investigating the transformation from sensory signals into motor commands. In insects, thoracic ganglia (TG) play an important role in motor control. To understand the functional organization of TG, an atlas is useful. However, except for the fruitfly, no three-dimensional atlas of TG has not been reported for insects. In this study, we generated a three-dimensional atlas of prothoracic, mesothoracic, and metathoracic ganglia in the praying mantis (Tenodera aridifolia). First, we observed serial sections of the prothoracic ganglion stained with hematoxylin and eosin to identify longitudinal tracts and transverse commissures. We then visualized neuropil areas by immunostaining whole-mount TG with an anti-synapsin antibody. Before labeling each neuropil area, standardization using the iterative shape averaging method was applied to images to make neuropil contours distinct. Neuropil areas in TG were defined based on their shape and relative position to tracts and commissures. Finally, a three-dimensional atlas was reconstructed from standardized images of the TG. The standard TG are available at the Comparative Neuroscience Platform website (cns.neuroinf.jp/modules/xoonips/detail.php?item_id=11946) and can be used as a common reference map to combine the anatomical data obtained from different individuals.
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Affiliation(s)
- Kentaro Fujiki
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan
| | - Mihoko Nagase
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan
| | - Keigo Takaki
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan
| | - Hidehiro Watanabe
- Department of Earth System Science, Faculty of Science, Fukuoka University, Fukuoka, Japan
| | - Yoshifumi Yamawaki
- Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan
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32
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Chu X, Heinze S, Ian E, Berg BG. A Novel Major Output Target for Pheromone-Sensitive Projection Neurons in Male Moths. Front Cell Neurosci 2020; 14:147. [PMID: 32581719 PMCID: PMC7294775 DOI: 10.3389/fncel.2020.00147] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 05/04/2020] [Indexed: 01/13/2023] Open
Abstract
Even though insects have comparably small brains, they achieve astoundingly complex behaviors. One example is flying moths tracking minute amounts of pheromones using olfactory circuits. The tracking distance can be up to 1 km, which makes it essential that male moths respond efficiently and reliably to very few pheromone molecules. The male-specific macroglomerular complex (MGC) in the moth antennal lobe contains circuitry dedicated to pheromone processing. Output neurons from this region project along three parallel pathways, the medial, mediolateral, and lateral tracts. The MGC-neurons of the lateral tract are least described and their functional significance is mainly unknown. We used mass staining, calcium imaging, and intracellular recording/staining to characterize the morphological and physiological properties of these neurons in the noctuid moth, Helicoverpa armigera. All lateral-tract MGC neurons targeted the column, a small region within the superior intermediate neuropil. We identified this region as a unique converging site for MGC lateral-tract neurons responsive to pheromones, as well as a dense congregating site for plant odor information since a substantial number of lateral-tract neurons from ordinary glomeruli (OG) also terminates in this region. The lateral-tract MGC-neurons responded with a shorter peak latency than the well-described neurons in the medial tract. Different from the medial-tract MGC neurons encoding odor quality important for species-specific signal identification, those in the lateral tract convey a more robust and rapid signal-potentially important for fast control of hard-wired behavior.
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Affiliation(s)
- Xi Chu
- Chemosensory Laboratory, Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Stanley Heinze
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden
| | - Elena Ian
- Chemosensory Laboratory, Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Bente G. Berg
- Chemosensory Laboratory, Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway
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33
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Habenstein J, Amini E, Grübel K, el Jundi B, Rössler W. The brain of
Cataglyphis
ants: Neuronal organization and visual projections. J Comp Neurol 2020; 528:3479-3506. [DOI: 10.1002/cne.24934] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 04/15/2020] [Accepted: 04/20/2020] [Indexed: 12/25/2022]
Affiliation(s)
- Jens Habenstein
- Biocenter, Behavioral Physiology and Sociobiology (Zoology II) University of Würzburg Würzburg Germany
| | - Emad Amini
- Biocenter, Neurobiology and Genetics University of Würzburg Würzburg Germany
| | - Kornelia Grübel
- Biocenter, Behavioral Physiology and Sociobiology (Zoology II) University of Würzburg Würzburg Germany
| | - Basil el Jundi
- Biocenter, Behavioral Physiology and Sociobiology (Zoology II) University of Würzburg Würzburg Germany
| | - Wolfgang Rössler
- Biocenter, Behavioral Physiology and Sociobiology (Zoology II) University of Würzburg Würzburg Germany
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34
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Darragh K, Montejo‐Kovacevich G, Kozak KM, Morrison CR, Figueiredo CME, Ready JS, Salazar C, Linares M, Byers KJRP, Merrill RM, McMillan WO, Schulz S, Jiggins CD. Species specificity and intraspecific variation in the chemical profiles of Heliconius butterflies across a large geographic range. Ecol Evol 2020; 10:3895-3918. [PMID: 32489619 PMCID: PMC7244815 DOI: 10.1002/ece3.6079] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 01/06/2020] [Accepted: 01/07/2020] [Indexed: 02/01/2023] Open
Abstract
In many animals, mate choice is important for the maintenance of reproductive isolation between species. Traits important for mate choice and behavioral isolation are predicted to be under strong stabilizing selection within species; however, such traits can also exhibit variation at the population level driven by neutral and adaptive evolutionary processes. Here, we describe patterns of divergence among androconial and genital chemical profiles at inter- and intraspecific levels in mimetic Heliconius butterflies. Most variation in chemical bouquets was found between species, but there were also quantitative differences at the population level. We found a strong correlation between interspecific chemical and genetic divergence, but this correlation varied in intraspecific comparisons. We identified "indicator" compounds characteristic of particular species that included compounds already known to elicit a behavioral response, suggesting an approach for identification of candidate compounds for future behavioral studies in novel systems. Overall, the strong signal of species identity suggests a role for these compounds in species recognition, but with additional potentially neutral variation at the population level.
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Affiliation(s)
- Kathy Darragh
- Department of ZoologyUniversity of CambridgeCambridgeUK
- Smithsonian Tropical Research InstitutePanama CityPanama
| | | | | | - Colin R. Morrison
- Smithsonian Tropical Research InstitutePanama CityPanama
- Department of Integrative BiologyThe University of Texas at AustinAustinTXUSA
| | | | - Jonathan S. Ready
- Institute for Biological SciencesUniversidade Federal do ParáBelémBrazil
| | - Camilo Salazar
- Biology ProgramFaculty of Natural Sciences and MathematicsUniversidad del RosarioBogotaColombia
| | - Mauricio Linares
- Biology ProgramFaculty of Natural Sciences and MathematicsUniversidad del RosarioBogotaColombia
| | - Kelsey J. R. P. Byers
- Department of ZoologyUniversity of CambridgeCambridgeUK
- Smithsonian Tropical Research InstitutePanama CityPanama
| | - Richard M. Merrill
- Smithsonian Tropical Research InstitutePanama CityPanama
- Division of Evolutionary BiologyFaculty of BiologyLudwig‐Maximilians‐Universität MünchenMunichGermany
| | | | - Stefan Schulz
- Institute of Organic ChemistryTechnische Universität BraunschweigBraunschweigGermany
| | - Chris D. Jiggins
- Department of ZoologyUniversity of CambridgeCambridgeUK
- Smithsonian Tropical Research InstitutePanama CityPanama
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35
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Strausfeld NJ, Wolff GH, Sayre ME. Mushroom body evolution demonstrates homology and divergence across Pancrustacea. eLife 2020; 9:e52411. [PMID: 32124731 PMCID: PMC7054004 DOI: 10.7554/elife.52411] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 02/03/2020] [Indexed: 02/06/2023] Open
Abstract
Descriptions of crustacean brains have focused mainly on three highly derived lineages of malacostracans: the reptantian infraorders represented by spiny lobsters, lobsters, and crayfish. Those descriptions advocate the view that dome- or cap-like neuropils, referred to as 'hemiellipsoid bodies,' are the ground pattern organization of centers that are comparable to insect mushroom bodies in processing olfactory information. Here we challenge the doctrine that hemiellipsoid bodies are a derived trait of crustaceans, whereas mushroom bodies are a derived trait of hexapods. We demonstrate that mushroom bodies typify lineages that arose before Reptantia and exist in Reptantia thereby indicating that the mushroom body, not the hemiellipsoid body, provides the ground pattern for both crustaceans and hexapods. We show that evolved variations of the mushroom body ground pattern are, in some lineages, defined by extreme diminution or loss and, in others, by the incorporation of mushroom body circuits into lobeless centers. Such transformations are ascribed to modifications of the columnar organization of mushroom body lobes that, as shown in Drosophila and other hexapods, contain networks essential for learning and memory.
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Affiliation(s)
- Nicholas James Strausfeld
- Department of Neuroscience, School of Mind, Brain and BehaviorUniversity of ArizonaTucsonUnited States
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36
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Adden A, Wibrand S, Pfeiffer K, Warrant E, Heinze S. The brain of a nocturnal migratory insect, the Australian Bogong moth. J Comp Neurol 2020; 528:1942-1963. [PMID: 31994724 DOI: 10.1002/cne.24866] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 01/16/2020] [Accepted: 01/18/2020] [Indexed: 12/12/2022]
Abstract
Every year, millions of Australian Bogong moths (Agrotis infusa) complete an astonishing journey: In Spring, they migrate over 1,000 km from their breeding grounds to the alpine regions of the Snowy Mountains, where they endure the hot summer in the cool climate of alpine caves. In autumn, the moths return to their breeding grounds, where they mate, lay eggs and die. These moths can use visual cues in combination with the geomagnetic field to guide their flight, but how these cues are processed and integrated into the brain to drive migratory behavior is unknown. To generate an access point for functional studies, we provide a detailed description of the Bogong moth's brain. Based on immunohistochemical stainings against synapsin and serotonin (5HT), we describe the overall layout as well as the fine structure of all major neuropils, including the regions that have previously been implicated in compass-based navigation. The resulting average brain atlas consists of 3D reconstructions of 25 separate neuropils, comprising the most detailed account of a moth brain to date. Our results show that the Bogong moth brain follows the typical lepidopteran ground pattern, with no major specializations that can be attributed to their spectacular migratory lifestyle. These findings suggest that migratory behavior does not require widespread modifications of brain structure, but might be achievable via small adjustments of neural circuitry in key brain areas. Locating these subtle changes will be a challenging task for the future, for which our study provides an essential anatomical framework.
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Affiliation(s)
- Andrea Adden
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden
| | - Sara Wibrand
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden
| | | | - Eric Warrant
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden
| | - Stanley Heinze
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden.,NanoLund, Department of Biology, Lund University, Lund, Sweden
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37
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Catalán A, Briscoe AD, Höhna S. Drift and Directional Selection Are the Evolutionary Forces Driving Gene Expression Divergence in Eye and Brain Tissue of Heliconius Butterflies. Genetics 2019; 213:581-594. [PMID: 31467133 PMCID: PMC6781903 DOI: 10.1534/genetics.119.302493] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 08/24/2019] [Indexed: 01/05/2023] Open
Abstract
Investigating gene expression evolution over micro- and macroevolutionary timescales will expand our understanding of the role of gene expression in adaptation and speciation. In this study, we characterized the evolutionary forces acting on gene expression levels in eye and brain tissue of five Heliconius butterflies with divergence times of ∼5-12 MYA. We developed and applied Brownian motion (BM) and Ornstein-Uhlenbeck (OU) models to identify genes whose expression levels are evolving through drift, stabilizing selection, or a lineage-specific shift. We found that 81% of the genes evolve under genetic drift. When testing for branch-specific shifts in gene expression, we detected 368 (16%) shift events. Genes showing a shift toward upregulation have significantly lower gene expression variance than those genes showing a shift leading toward downregulation. We hypothesize that directional selection is acting in shifts causing upregulation, since transcription is costly. We further uncovered through simulations that parameter estimation of OU models is biased when using small phylogenies and only becomes reliable with phylogenies having ≥ 50 taxa. Therefore, we developed a new statistical test based on BM to identify highly conserved genes (i.e., evolving under strong stabilizing selection), which comprised 3% of the orthoclusters. In conclusion, we found that drift is the dominant evolutionary force driving gene expression evolution in eye and brain tissue in Heliconius Nevertheless, the higher proportion of genes evolving under directional than under stabilizing selection might reflect species-specific selective pressures on vision and the brain that are necessary to fulfill species-specific requirements.
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Affiliation(s)
- Ana Catalán
- Department of Evolutionary Biology, Evolutionary Biology Centre (EBC), Uppsala University, 75236, Sweden
- Division of Evolutionary Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried 82152, Germany
| | - Adriana D Briscoe
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92697
| | - Sebastian Höhna
- Division of Evolutionary Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried 82152, Germany
- Department of Earth and Environmental Sciences, Paleontology and Geobiology, 80333 Munich, Germany
- GeoBio-Center, Ludwig-Maximilians-Universität München, 80333 Munich, Germany
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38
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Xie GY, Ma BW, Liu XL, Chang YJ, Chen WB, Li GP, Feng HQ, Zhang YJ, Berg BG, Zhao XC. Brain Organization of Apolygus lucorum: A Hemipteran Species With Prominent Antennal Lobes. Front Neuroanat 2019; 13:70. [PMID: 31379518 PMCID: PMC6654032 DOI: 10.3389/fnana.2019.00070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 06/24/2019] [Indexed: 11/13/2022] Open
Abstract
The anatomical organization of distinct regions in the insect brain often reflects their functions. In the present study, the brain structure of Apolygus lucorum was examined by using immunolabeling and three-dimensional reconstruction. The results revealed the location and volume of prominent neuropils, such as the antennal lobes (AL), optic lobes (OL), anterior optic tubercles (AOTU), central body (CB), lateral accessory lobes (LAL), mushroom lobes, and distinct tritocerebral neuropils. As expected, this brain is similar to that of other insects. One exception, however, is that the antennal lobes were found to be the most prominent neuropils. Their size relative to the entire brain is the largest among all insect species studied so far. In contrast, the calyx, a region getting direct input from the antennal lobe, has a smaller size relative to the brain than that of other species. These findings may suggest that olfaction plays an essential role for A. lucorum.
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Affiliation(s)
- Gui-Ying Xie
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Bai-Wei Ma
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Xiao-Lan Liu
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Ya-Jun Chang
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Wen-Bo Chen
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, China
| | - Guo-Ping Li
- Institute of Plant Protection, Henan Academy of Agricultural Sciences (HAAS), Zhengzhou, China
| | - Hong-Qiang Feng
- Institute of Plant Protection, Henan Academy of Agricultural Sciences (HAAS), Zhengzhou, China
| | - Yong-Jun Zhang
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Bente G Berg
- Department of Psychology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Xin-Cheng Zhao
- Department of Entomology, College of Plant Protection, Henan Agricultural University, Zhengzhou, China
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Macias-Muñoz A, Rangel Olguin AG, Briscoe AD. Evolution of Phototransduction Genes in Lepidoptera. Genome Biol Evol 2019; 11:2107-2124. [PMID: 31298692 PMCID: PMC6698658 DOI: 10.1093/gbe/evz150] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2019] [Indexed: 12/17/2022] Open
Abstract
Vision is underpinned by phototransduction, a signaling cascade that converts light energy into an electrical signal. Among insects, phototransduction is best understood in Drosophila melanogaster. Comparison of D. melanogaster against three insect species found several phototransduction gene gains and losses, however, lepidopterans were not examined. Diurnal butterflies and nocturnal moths occupy different light environments and have distinct eye morphologies, which might impact the expression of their phototransduction genes. Here we investigated: 1) how phototransduction genes vary in gene gain or loss between D. melanogaster and Lepidoptera, and 2) variations in phototransduction genes between moths and butterflies. To test our prediction of phototransduction differences due to distinct visual ecologies, we used insect reference genomes, phylogenetics, and moth and butterfly head RNA-Seq and transcriptome data. As expected, most phototransduction genes were conserved between D. melanogaster and Lepidoptera, with some exceptions. Notably, we found two lepidopteran opsins lacking a D. melanogaster ortholog. Using antibodies we found that one of these opsins, a candidate retinochrome, which we refer to as unclassified opsin (UnRh), is expressed in the crystalline cone cells and the pigment cells of the butterfly, Heliconius melpomene. Our results also show that butterflies express similar amounts of trp and trpl channel mRNAs, whereas moths express ∼50× less trp, a potential adaptation to darkness. Our findings suggest that while many single-copy D. melanogaster phototransduction genes are conserved in lepidopterans, phototransduction gene expression differences exist between moths and butterflies that may be linked to their visual light environment.
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Affiliation(s)
- Aide Macias-Muñoz
- Department of Ecology and Evolutionary Biology, University of California, Irvine
| | | | - Adriana D Briscoe
- Department of Ecology and Evolutionary Biology, University of California, Irvine
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Eriksson M, Nylin S, Carlsson MA. Insect brain plasticity: effects of olfactory input on neuropil size. ROYAL SOCIETY OPEN SCIENCE 2019; 6:190875. [PMID: 31598254 PMCID: PMC6731737 DOI: 10.1098/rsos.190875] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 07/23/2019] [Indexed: 06/10/2023]
Abstract
Insect brains are known to express a high degree of experience-dependent structural plasticity. One brain structure in particular, the mushroom body (MB), has been attended to in numerous studies as it is implicated in complex cognitive processes such as olfactory learning and memory. It is, however, poorly understood to what extent sensory input per se affects the plasticity of the mushroom bodies. By performing unilateral blocking of olfactory input on immobilized butterflies, we were able to measure the effect of passive sensory input on the volumes of antennal lobes (ALs) and MB calyces. We showed that the primary and secondary olfactory neuropils respond in different ways to olfactory input. ALs show absolute experience-dependency and increase in volume only if receiving direct olfactory input from ipsilateral antennae, while MB calyx volumes were unaffected by the treatment and instead show absolute age-dependency in this regard. We therefore propose that cognitive processes related to behavioural expressions are needed in order for the calyx to show experience-dependent volumetric expansions. Our results indicate that such experience-dependent volumetric expansions of calyces observed in other studies may have been caused by cognitive processes rather than by sensory input, bringing some causative clarity to a complex neural phenomenon.
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41
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Jaumann S, Seid MA, Simons M, Smith AR. Queen Dominance May Reduce Worker Mushroom Body Size in a Social Bee. Dev Neurobiol 2019; 79:596-607. [PMID: 31207130 DOI: 10.1002/dneu.22705] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 06/10/2019] [Accepted: 06/11/2019] [Indexed: 01/20/2023]
Abstract
The mushroom body (MB) is an area of the insect brain involved in learning, memory, and sensory integration. Here, we used the sweat bee Megalopta genalis (Halictidae) to test for differences between queens and workers in the volume of the MB calyces. We used confocal microscopy to measure the volume of the whole brain, MB calyces, optic lobes, and antennal lobes of queens and workers. Queens had larger brains, larger MB calyces, and a larger MB calyces:whole brain ratio than workers, suggesting an effect of social dominance in brain development. This could result from social interactions leading to smaller worker MBs, or larger queen MBs. It could also result from other factors, such as differences in age or sensory experience. To test these explanations, we next compared queens and workers to other groups. We compared newly emerged bees, bees reared in isolation for 10 days, bees initiating new observation nests, and bees initiating new natural nests collected from the field to queens and workers. Queens did not differ from these other groups. We suggest that the effects of queen dominance over workers, rather than differences in age, experience, or reproductive status, are responsible for the queen-worker differences we observed. Worker MB development may be affected by queen aggression directly and/or manipulation of larval nutrition, which is provisioned by the queen. We found no consistent differences in the size of antennal lobes or optic lobes associated with differences in age, experience, reproductive status, or social caste.
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Affiliation(s)
- Sarah Jaumann
- Department of Biological Sciences, George Washington University, Washington, District of Columbia
| | - Marc A Seid
- Biology Department, University of Scranton, Scranton, Pennsylvania
| | - Meagan Simons
- Department of Biological Sciences, George Washington University, Washington, District of Columbia
| | - Adam R Smith
- Department of Biological Sciences, George Washington University, Washington, District of Columbia
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Sayre ME, Strausfeld NJ. Mushroom bodies in crustaceans: Insect-like organization in the caridid shrimp Lebbeus groenlandicus. J Comp Neurol 2019; 527:2371-2387. [PMID: 30861118 DOI: 10.1002/cne.24678] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 02/27/2019] [Accepted: 02/28/2019] [Indexed: 11/11/2022]
Abstract
Paired centers in the forebrain of insects, called the mushroom bodies, have become the most investigated brain region of any invertebrate due to novel genetic strategies that relate unique morphological attributes of these centers to their functional roles in learning and memory. Mushroom bodies possessing all the morphological attributes of those in dicondylic insects have been identified in mantis shrimps, basal hoplocarid crustaceans that are sister to Eumalacostraca, the most species-rich group of Crustacea. However, unless other examples of mushroom bodies can be identified in Eumalacostraca, the possibility is that mushroom body-like centers may have undergone convergent evolution in Hoplocarida and are unique to this crustacean lineage. Here, we provide evidence that speaks against convergent evolution, describing in detail the paired mushroom bodies in the lateral protocerebrum of a decapod crustacean, Lebbeus groenlandicus, a species belonging to the infraorder Caridea, an ancient lineage of Eumalacostraca.
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Affiliation(s)
- Marcel E Sayre
- Lund Vision Group, Department of Biology, Lund University, Lund, Sweden
| | - Nicholas J Strausfeld
- Department of Neuroscience, School of Mind, Brain and Behavior, University of Arizona, Tucson, Arizona
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Merrill RM, Rastas P, Martin SH, Melo MC, Barker S, Davey J, McMillan WO, Jiggins CD. Genetic dissection of assortative mating behavior. PLoS Biol 2019; 17:e2005902. [PMID: 30730873 PMCID: PMC6366751 DOI: 10.1371/journal.pbio.2005902] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Accepted: 11/06/2018] [Indexed: 12/26/2022] Open
Abstract
The evolution of new species is made easier when traits under divergent ecological selection are also mating cues. Such ecological mating cues are now considered more common than previously thought, but we still know little about the genetic changes underlying their evolution or more generally about the genetic basis for assortative mating behaviors. Both tight physical linkage and the existence of large-effect preference loci will strengthen genetic associations between behavioral and ecological barriers, promoting the evolution of assortative mating. The warning patterns of Heliconius melpomene and H. cydno are under disruptive selection due to increased predation of nonmimetic hybrids and are used during mate recognition. We carried out a genome-wide quantitative trait locus (QTL) analysis of preference behaviors between these species and showed that divergent male preference has a simple genetic basis. We identify three QTLs that together explain a large proportion (approximately 60%) of the difference in preference behavior observed between the parental species. One of these QTLs is just 1.2 (0-4.8) centiMorgans (cM) from the major color pattern gene optix, and, individually, all three have a large effect on the preference phenotype. Genomic divergence between H. cydno and H. melpomene is high but broadly heterogenous, and admixture is reduced at the preference-optix color pattern locus but not the other preference QTLs. The simple genetic architecture we reveal will facilitate the evolution and maintenance of new species despite ongoing gene flow by coupling behavioral and ecological aspects of reproductive isolation.
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Affiliation(s)
- Richard M. Merrill
- Division of Evolutionary Biology, Ludwig-Maximilians-Universität, München, Germany
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
- Smithsonian Tropical Research Institute, Panama City, Panama
| | - Pasi Rastas
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Simon H. Martin
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Maria C. Melo
- Smithsonian Tropical Research Institute, Panama City, Panama
- IST Austria, Klosterburg, Austria
| | - Sarah Barker
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - John Davey
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
- Department of Biology, University of York, York, United Kingdom
| | | | - Chris D. Jiggins
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
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Brain evolution in social insects: advocating for the comparative approach. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 205:13-32. [DOI: 10.1007/s00359-019-01315-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 01/09/2019] [Accepted: 01/11/2019] [Indexed: 10/27/2022]
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van Schooten B, Godoy-Vitorino F, McMillan WO, Papa R. Conserved microbiota among young Heliconius butterfly species. PeerJ 2018; 6:e5502. [PMID: 30310733 PMCID: PMC6173163 DOI: 10.7717/peerj.5502] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 08/01/2018] [Indexed: 12/03/2022] Open
Abstract
Background Insects are the most diverse group of animals which have established intricate evolutionary interactions with bacteria. However, the importance of these interactions is still poorly understood. Few studies have focused on a closely related group of insect species, to test the similarities and differences between their microbiota. Heliconius butterflies are a charismatic recent insect radiation that evolved the unique ability to use pollen as a protein source, which affected life history traits and resulted in an elevated speciation rates. We hypothesize that different Heliconius butterflies sharing a similar trophic pollen niche, harbor a similar gut flora within species, population and sexes. Methods To test our hypothesis, we characterized the microbiota of 38 adult male and female butterflies representing six species of Heliconius butterflies and 2 populations of the same species. We sequenced the V4 region of the 16S rRNA gene with the Roche 454 system and analyzed the data with standard tools for microbiome analysis. Results Overall, we found a low microbial diversity with only 10 OTUs dominating across all individuals, mostly Proteobacteria and Firmicutes, which accounted for 99.5% of the bacterial reads. When rare reads were considered, we identified a total of 406 OTUs across our samples. We identified reads within Phyla Chlamydiae, found in 5 butterflies of four species. Interestingly, only three OTUs were shared among all 38 individuals (Bacillus, Enterococcus and Enterobacteriaceae). Altogether, the high individual variation overshadowed species and sex differences. Thus, bacterial communities were not structured randomly with 13% of beta-diversity explained by species, and 40 rare OTUs being significantly different across species. Finally, 13 OTUs, including the intercellular symbiont Spiroplasma, varied significantly in relative abundance between males and females. Discussion The Heliconius microbial communities in these 38 individuals show a low diversity with few differences in the rare microbes between females, males, species or populations. Indeed, Heliconius butterflies, similarly to other insects, are dominated by few OTUs, mainly from Proteobacteria and Firmicutes. The overall low microbial diversity observed contrasts with the high intra-species variation in microbiome composition. This could indicate that much of the microbiome maybe acquired from their surroundings. The significant differences between species and sexes were restricted to rare taxa, which could be important for microbial community stability under changing conditions as seen in other host-microbiome systems. The presence of symbionts like Spiroplasma or Chlamydiae, identified in this study for the first time in Heliconius, could play a vital role in their behavior and evolution by vertical transmission. Altogether, our study represents a step forward into the description of the microbial diversity in a charismatic group of closely related butterflies.
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Affiliation(s)
- Bas van Schooten
- Department of Biology, University of Puerto Rico, Rio Piedras Campus, San Juan, Puerto Rico
| | - Filipa Godoy-Vitorino
- Department of Microbiology and Medical Zoology, School of Medicine, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico
| | | | - Riccardo Papa
- Department of Biology, University of Puerto Rico, Rio Piedras Campus, San Juan, Puerto Rico.,Smithsonian Tropical Research Institute, Panamá, Panama.,University of Puerto Rico, Molecular Sciences and Research Center, San Juan, Puerto Rico
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Pomaville MB, Lent DD. Multiple Representations of Space by the Cockroach, Periplaneta americana. Front Psychol 2018; 9:1312. [PMID: 30104993 PMCID: PMC6077775 DOI: 10.3389/fpsyg.2018.01312] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 07/09/2018] [Indexed: 11/30/2022] Open
Abstract
When cockroaches are trained to a visual–olfactory cue pairing using the antennal projection response (APR), they can form different memories for the location of a visual cue. A series of experiments, each examining memory for the spatial location of a visual cue, were performed using restrained cockroaches. The first group of experiments involved training cockroaches to associate a visual cue (CS—green LED) with an odor cue (US) in the presence or absence of a second visual reference cue (white LED). These experiments revealed that cockroaches have at least two forms of spatial memory. First, it was found that during learning, the movements of the antennae in response to the odor influenced the cockroaches’ memory. If they use only one antenna, cockroaches form a memory that results in an APR being elicited to the CS irrespective of its location in space. When using both antennae, the cockroaches resulting memory leads to an APR to the CS that is spatially confined to within 15° of the trained position. This memory represents an egocentric spatial representation. Second, the cockroaches simultaneously formed a memory for the angular spatial relationships between two visual cues when trained in the presence of a second visual reference cue. This training provided the cockroaches an allocentric representation or visual snapshot of the environment. If both egocentric and the visual snapshot were available to the cockroach to localize the learned cue, the visual snapshot determined the behavioral response in this assay. Finally, the split-brain assay was used to characterize the cockroach’s ability to establish a memory for the angular relationship between two visual cues with half a brain. Split-brain cockroaches were trained to unilaterally associate a pair of visual cues (CS—green LED and reference—white LED) with an odor cue (US). Split-brain cockroaches learned the general arrangement of the visual cues (i.e., the green LED is right of the white LED), but not the precise angular relationship. These experiments provide new insight into spatial memory processes in the cockroach.
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Affiliation(s)
- Matthew B Pomaville
- Department of Biology, California State University, Fresno, CA, United States
| | - David D Lent
- Department of Biology, California State University, Fresno, CA, United States
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van Dijk LJA, Janz N, Schäpers A, Gamberale-Stille G, Carlsson MA. Experience-dependent mushroom body plasticity in butterflies: consequences of search complexity and host range. Proc Biol Sci 2018; 284:rspb.2017.1594. [PMID: 29093221 PMCID: PMC5698644 DOI: 10.1098/rspb.2017.1594] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 10/06/2017] [Indexed: 01/02/2023] Open
Abstract
An ovipositing insect experiences many sensory challenges during her search for a suitable host plant. These sensory challenges become exceedingly pronounced when host range increases, as larger varieties of sensory inputs have to be perceived and processed in the brain. Neural capacities can be exceeded upon information overload, inflicting costs on oviposition accuracy. One presumed generalist strategy to diminish information overload is the acquisition of a focused search during its lifetime based on experiences within the current environment, a strategy opposed to a more genetically determined focus expected to be seen in relative specialists. We hypothesized that a broader host range is positively correlated with mushroom body (MB) plasticity, a brain structure related to learning and memory. To test this hypothesis, butterflies with diverging host ranges (Polygonia c-album, Aglais io and Aglais urticae) were subjected to differential environmental complexities for oviposition, after which ontogenetic MB calyx volume differences were compared among species. We found that the relative generalist species exhibited remarkable plasticity in ontogenetic MB volumes; MB growth was differentially stimulated based on the complexity of the experienced environment. For relative specialists, MB volume was more canalized. All in all, this study strongly suggests an impact of host range on brain plasticity in Nymphalid butterflies.
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Affiliation(s)
| | - Niklas Janz
- Department of Zoology, Stockholm University, 106 91 Stockholm, Sweden
| | | | | | - Mikael A Carlsson
- Department of Zoology, Stockholm University, 106 91 Stockholm, Sweden
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Steinhoff POM, Liedtke J, Sombke A, Schneider JM, Uhl G. Early environmental conditions affect the volume of higher-order brain centers in a jumping spider. J Zool (1987) 2017. [DOI: 10.1111/jzo.12512] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- P. O. M. Steinhoff
- General and Systematic Zoology; Zoological Institute and Museum; University of Greifswald; Greifswald Germany
| | - J. Liedtke
- Biocenter Grindel; Zoological Institute; University of Hamburg; Hamburg Germany
| | - A. Sombke
- Cytology and Evolutionary Biology; Zoological Institute and Museum; University of Greifswald; Greifswald Germany
| | - J. M. Schneider
- Biocenter Grindel; Zoological Institute; University of Hamburg; Hamburg Germany
| | - G. Uhl
- General and Systematic Zoology; Zoological Institute and Museum; University of Greifswald; Greifswald Germany
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Wolff GH, Thoen HH, Marshall J, Sayre ME, Strausfeld NJ. An insect-like mushroom body in a crustacean brain. eLife 2017; 6:29889. [PMID: 28949916 PMCID: PMC5614564 DOI: 10.7554/elife.29889] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 08/25/2017] [Indexed: 01/02/2023] Open
Abstract
Mushroom bodies are the iconic learning and memory centers of insects. No previously described crustacean possesses a mushroom body as defined by strict morphological criteria although crustacean centers called hemiellipsoid bodies, which serve functions in sensory integration, have been viewed as evolutionarily convergent with mushroom bodies. Here, using key identifiers to characterize neural arrangements, we demonstrate insect-like mushroom bodies in stomatopod crustaceans (mantis shrimps). More than any other crustacean taxon, mantis shrimps display sophisticated behaviors relating to predation, spatial memory, and visual recognition comparable to those of insects. However, neuroanatomy-based cladistics suggesting close phylogenetic proximity of insects and stomatopod crustaceans conflicts with genomic evidence showing hexapods closely related to simple crustaceans called remipedes. We discuss whether corresponding anatomical phenotypes described here reflect the cerebral morphology of a common ancestor of Pancrustacea or an extraordinary example of convergent evolution. With more than four million species, arthropods are the largest and most diverse group of animals on the planet and include, for example, crustaceans, insects and spiders. They are defined by their segmented bodies, hard outer skeletons and jointed limbs. All arthropods share a common ancestor that lived more than 550 million years ago. Exactly how this ancestral arthropod gave rise to the myriad species that exist today is unclear but we know that at some point the arthropod family tree split into branches, one of which went on to become the crustaceans. The crustacean branch then split again, giving rise to a line of descendants that would become the insects. But although insects evolved from crustaceans, the brains of insects possess structures that those of crustaceans do not. Known as mushroom bodies, these structures help to form and store memories. Their absence in crustaceans has therefore been an enduring mystery. Wolff et al. now add a piece to the puzzle by showing that one group of modern-day crustaceans, the mantis shrimps, does in fact possess mushroom bodies. By visualizing cells and pathways within the brains of mantis shrimps, and also a number of closely related species, Wolff et al. show that only these shrimps possess true mushroom bodies. However, some of the mantis shrimp’s close relatives possess a few attributes of these structures. This suggests that mushroom bodies are evolutionarily ancient structures that arose in a common ancestor of insects and crustaceans, before being lost or radically modified in most of the crustaceans. So why did this happen? Mantis shrimps are top predators with excellent vision that hunt over considerable distances, requiring them to evaluate and memorize complex features of their environment. These cognitive demands, which might not be shared by other crustaceans, may have led to the mantis shrimps retaining their mushroom bodies. Further research into the brains and behavior of the mantis shrimp may provide insights into how mushroom bodies construct memories of a complex sensory world.
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Affiliation(s)
| | | | - Justin Marshall
- Sensory Neurobiology Group, University of Queensland, Brisbane, Australia
| | - Marcel E Sayre
- Department of Neuroscience, School of Mind, Brain and Behavior, University of Arizona, Tucson, United States
| | - Nicholas James Strausfeld
- Department of Neuroscience, School of Mind, Brain and Behavior, University of Arizona, Tucson, United States
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50
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de Castro ÉCP, Zagrobelny M, Cardoso MZ, Bak S. The arms race between heliconiine butterflies and Passiflora plants - new insights on an ancient subject. Biol Rev Camb Philos Soc 2017; 93:555-573. [PMID: 28901723 DOI: 10.1111/brv.12357] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 07/04/2017] [Accepted: 07/05/2017] [Indexed: 01/06/2023]
Abstract
Heliconiines are called passion vine butterflies because they feed exclusively on Passiflora plants during the larval stage. Many features of Passiflora and heliconiines indicate that they have radiated and speciated in association with each other, and therefore this model system was one of the first examples used to exemplify coevolution theory. Three major adaptations of Passiflora plants supported arguments in favour of their coevolution with heliconiines: unusual variation of leaf shape within the genus; the occurrence of yellow structures mimicking heliconiine eggs; and their extensive diversity of defence compounds called cyanogenic glucosides. However, the protection systems of Passiflora plants go beyond these three features. Trichomes, mimicry of pathogen infection through variegation, and production of extrafloral nectar to attract ants and other predators of their herbivores, are morphological defences reported in this plant genus. Moreover, Passiflora plants are well protected chemically, not only by cyanogenic glucosides, but also by other compounds such as alkaloids, flavonoids, saponins, tannins and phenolics. Heliconiines can synthesize cyanogenic glucosides themselves, and their ability to handle these compounds was probably one of the most crucial adaptations that allowed the ancestor of these butterflies to feed on Passiflora plants. Indeed, it has been shown that Heliconius larvae can sequester cyanogenic glucosides and alkaloids from their host plants and utilize them for their own benefit. Recently, it was discovered that Heliconius adults have highly accurate visual and chemosensory systems, and the expansion of brain structures that can process such information allows them to memorize shapes and display elaborate pre-oviposition behaviour in order to defeat visual barriers evolved by Passiflora species. Even though the heliconiine-Passiflora model system has been intensively studied, the forces driving host-plant preference in these butterflies remain unclear. New studies have shown that host-plant preference seems to be genetically controlled, but in many species there is some plasticity in this choice and preferences can even be induced. Although much knowledge regarding the coevolution of Passiflora plants and heliconiine butterflies has accumulated in recent decades, there remain many exciting unanswered questions concerning this model system.
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Affiliation(s)
- Érika C P de Castro
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871, Copenhagen, Denmark
| | - Mika Zagrobelny
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871, Copenhagen, Denmark
| | - Márcio Z Cardoso
- Department of Ecology, Federal University of Rio Grande do Norte, Natal, 59078-900, Brazil
| | - Søren Bak
- Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871, Copenhagen, Denmark
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