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Caputi AA. Living life with an electric touch. J Exp Biol 2023; 226:jeb246060. [PMID: 38009325 DOI: 10.1242/jeb.246060] [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] [Indexed: 11/28/2023]
Abstract
The electric organ discharges (EODs) produced by weakly electric fish have long been a source of scientific intrigue and inspiration. The study of these species has contributed to our understanding of the organization of fixed action patterns, as well as enriching general imaging theory by unveiling the dual impact of an agent's actions on the environment and its own sensory system during the imaging process. This Centenary Review firstly compares how weakly electric fish generate species- and sex-specific stereotyped electric fields by considering: (1) peripheral mechanisms, including the geometry, channel repertoire and innervation of the electrogenic units; (2) the organization of the electric organs (EOs); and (3) neural coordination mechanisms. Secondly, the Review discusses the threefold function of the fish-centered electric fields: (1) to generate electric signals that encode the material, geometry and distance of nearby objects, serving as a short-range sensory modality or 'electric touch'; (2) to mark emitter identity and location; and (3) to convey social messages encoded in stereotypical modulations of the electric field that might be considered as species-specific communication symbols. Finally, this Review considers a range of potential research directions that are likely to be productive in the future.
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Affiliation(s)
- Angel Ariel Caputi
- Sistema Nacional de Investigadores - Uruguay, Av. Wilson Ferreira Aldunate 1219, Pando, PC 15600, Uruguay
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2
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Zlenko DV, Olshanskiy VM, Orlov AA, Kasumyan AO, MacMahon E, Wei X, Moller P. Visualization of electric fields and associated behavior in fish and other aquatic animals. Behav Res Methods 2023:10.3758/s13428-023-02175-5. [PMID: 37578570 DOI: 10.3758/s13428-023-02175-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/12/2023] [Indexed: 08/15/2023]
Abstract
In some fish lineages, evolution has led to unique sensory adaptations that provide information which is not available to terrestrial animals. These sensory systems include, among others, electroreception, which together with the ability of fish to generate electric discharges plays a role in social communication and object location. Most studies on electric phenomena in aquatic animals are dedicated to selected groups of electric fishes that regularly generate electric signals (Mormyriformes, Gymnotiformes). There exist, however, several species (hitherto described as non-electric) which, though able to perceive electric signals, have now been found to also generate them. In this article, we introduce a tool that we have designed to investigate such electric activity. This required significant adaptations of the equipment used in fish with regular discharge generation. The necessary improvements were realized by using a multielectrode registration setup allowing simultaneous visualization and quantification of behavior and associated electric activity of fish, alone or in groups, with combined electro-video clips. Precise synchronization of locomotor and electric behaviors made it possible to determine the electrically active fish in a group, and also the location of the electrogenic structure inside the fish's body. Our simple registration procedure, together with data presentation, should attract a broad audience of scientists taking up the challenge of uncovering electric phenomena in aquatic animals currently treated as electrically inactive.
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Affiliation(s)
- Dmitry V Zlenko
- A.N. Severtsov Institute of Ecology and Evolution, Moscow, Russia.
| | | | - Andrey A Orlov
- A.N. Severtsov Institute of Ecology and Evolution, Moscow, Russia
| | - Alexander O Kasumyan
- A.N. Severtsov Institute of Ecology and Evolution, Moscow, Russia
- M.V. Lomonosov Moscow State University, Moscow, Russia
| | | | - Xue Wei
- Harbin Engineering University, Harbin, China
| | - Peter Moller
- Department of Psychology Hunter College, New York, NY, USA
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3
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Taphorn DC, Liverpool E, Lujan NK, DoNascimiento C, Hemraj DD, Crampton WGR, Kolmann MA, Fontenelle JP, de Souza LS, Werneke DC, Ram M, Bloom DD, Sidlauskas BL, Holm E, Lundberg JG, Sabaj MH, Bernard C, Armbruster JW, López-Fernández H. Annotated checklist of the primarily freshwater fishes of Guyana. PROCEEDINGS OF THE ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA 2022. [DOI: 10.1635/053.168.0101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
| | - Elford Liverpool
- Department of Biology, Faculty of Natural Sciences, University of Guyana, Turkeyen, East Coast Demerara, 413741, Georgetown, Guyana.
| | - Nathan K. Lujan
- Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, M5S 2C6, Canada and Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada
| | - Carlos DoNascimiento
- Universidad de Antioquia, Grupo de Ictiología, Instituto de Biología, Calle 67 No. 53-108, Medellín, Antioquia, Colombia
| | - Devya D. Hemraj
- Centre for the Study of Biological Diversity, Department of Biology, Faculty of Natural Sciences, University of Guyana, Turkeyen Campus, Greater Georgetown, Guyana
| | | | - Matthew A. Kolmann
- Department of Biology, University of Louisville, Louisville, KY, 40292, USA
| | - João Pedro Fontenelle
- University of Toronto, Institute of Forestry and Conservation, 33 Willcocks St. Office 4004, M5S 3E8, Toronto, ON, Canada
| | - Lesley S. de Souza
- Field Museum of Natural History, 1400 S. Lake Shore, Chicago, IL, 60605 USA
| | - David C. Werneke
- Department of Biological Sciences, 101 Rouse, Auburn University, Auburn, AL, 36849, USA
| | - Mark Ram
- Department of Biology, Faculty of Natural Sciences, University of Guyana, Turkeyen Campus, Greater Georgetown, Guyana
| | - Devin D. Bloom
- Department of Biological Sciences and Institute of the Environment & Sustainability, Western Michigan University, Kalamazoo, MI, 49008-5410, USA
| | - Brian L. Sidlauskas
- Oregon State University, Department of Fisheries, Wildlife and Conservation Sciences, 104 Nash Hall, Corvallis, Oregon, 97331-3803 USA and Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, Dist
| | - Erling Holm
- Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, M5S 2C6, Canada
| | - John G. Lundberg
- The Academy of Natural Sciences of Drexel University, 1900 Benjamin Franklin Parkway, Philadelphia, PA, 19103, USA
| | - Mark H. Sabaj
- The Academy of Natural Sciences of Drexel University, 1900 Benjamin Franklin Parkway, Philadelphia, PA, 19103, USA
| | - Calvin Bernard
- Department of Biology, Faculty of Natural Sciences, University of Guyana, Turkeyen Campus, Greater Georgetown, Guyana
| | | | - Hernán López-Fernández
- Department of Ecology and Evolutionary Biology and Museum of Zoology, University of Michigan, 1105 North University Ave. Ann Arbor, MI, 48109, USA
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Waddell JC, Crampton WGR. Reproductive effort and terminal investment in a multi‐species assemblage of Amazon electric fish. ECOL MONOGR 2021. [DOI: 10.1002/ecm.1499] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Joseph C. Waddell
- Department of Biology University of Central Florida 4100 Libra Dr 32816 Orlando FL USA
- Department of Integrative and Computational Neurobiology Instituto de Investigaciones Biológicas Clemente Estable Av. Italia 3318 Montevideo 11600 Uruguay
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5
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Waddell JC, Caputi AA. The captivating effect of electric organ discharges: species, sex and orientation are embedded in every single received image. J Exp Biol 2021; 224:271071. [PMID: 34318315 DOI: 10.1242/jeb.243008] [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: 06/11/2021] [Accepted: 07/22/2021] [Indexed: 11/20/2022]
Abstract
Some fish communicate using pulsatile, stereotyped electric organ discharges (EODs) that exhibit species- and sex-specific time courses. To ensure reproductive success, they must be able to discriminate conspecifics from sympatric species in the muddy waters they inhabit. We have previously shown that fish in both Gymnotus and Brachyhypopomus genera use the electric field lines as a tracking guide to approach conspecifics (electrotaxis). Here, we show that the social species Brachyhypopomus gauderio uses electrotaxis to arrive abreast a conspecific, coming from behind. Stimulus image analysis shows that, even in a uniform field, every single EOD causes an image in which the gradient and the local field time courses contain enough information to allow the fish to evaluate the conspecific sex, and to find the path to reach it. Using a forced-choice test, we show that sexually mature individuals orient themselves along a uniform field in the direction encoded by the time course characteristic of the opposite sex. This indicates that these fish use the stimulus image profile as a spatial guidance clue to find a mate. Embedding species, sex and orientation cues is a particular example of how species can encode multiple messages in the same self-generated communication signal carrier, allowing for other signal parameters (e.g. EOD timing) to carry additional, often circumstantial, messages. This 'multiple messages' EOD embedding approach expressed in this species is likely to be a common and successful strategy that is widespread across evolutionary lineages and among varied signaling modalities.
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Affiliation(s)
- Joseph C Waddell
- Departamento de Neurociencias Integrativas y Computacionales, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, Montevideo, CP 11600, Uruguay
| | - Angel A Caputi
- Departamento de Neurociencias Integrativas y Computacionales, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, Montevideo, CP 11600, Uruguay
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Waddell JC, Caputi AA. Electrocommunication in pulse Gymnotiformes: the role of electric organ discharge (EOD) time course in species identification. ACTA ACUST UNITED AC 2020; 223:jeb.226340. [PMID: 32748795 DOI: 10.1242/jeb.226340] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 07/02/2020] [Indexed: 11/20/2022]
Abstract
Understanding how individuals detect and recognize signals emitted by conspecifics is fundamental to discussions of animal communication. The species pair Gymnotus omarorum and Brachyhypopomus gauderio, found in syntopy in Uruguay, emit species-specific electric organ discharge (EOD) that can be sensed by both species. The aim of this study was to unveil whether either of these species is able to identify a conspecific EOD, and to investigate distinctive recognition signal features. We designed a forced-choice experiment using a natural behavior (i.e. tracking electric field lines towards their source) in which each fish had to choose between a conspecific and a heterospecific electric field. We found a clear pattern of preference for a conspecific waveform even when pulses were played within 1 Hz of the same rate. By manipulating the time course of the explored signals, we found that the signal features for preference between conspecific and heterospecific waveforms were embedded in the time course of the signals. This study provides evidence that pulse Gymnotiformes can recognize a conspecific exclusively through species-specific electrosensory signals. It also suggests that the key signal features for species differentiation are probably encoded by burst coder electroreceptors. Given these results, and because receptors are sharply tuned to amplitude spectra and also tuned to phase spectra, we extend the electric color hypothesis used in the evaluation of objects to apply to communication signals.
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Affiliation(s)
- Joseph C Waddell
- Departamento de Neurociencias Integrativas y Computacionales, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, Montevideo, Uruguay
| | - Angel A Caputi
- Departamento de Neurociencias Integrativas y Computacionales, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, Montevideo, Uruguay
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Kim LY, Crampton WGR, Albert JS. Two New Species of Gymnotus (Gymnotiformes: Gymnotidae) from Brazil and Historical Biogeography of the Subgenus Lamontianus. COPEIA 2020. [DOI: 10.1643/ci-19-205] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Lesley Y. Kim
- Department of Biology, University of Louisiana at Lafayette, P.O. Box 43602, Lafayette, Louisiana 70504; . Send reprint requests to this address
| | - William G. R. Crampton
- Department of Biology, University of Central Florida, Biological Sciences Bldg., 4110 Libra Drive, Orlando, Florida 32816-2368;
| | - James S. Albert
- Department of Biology, University of Louisiana at Lafayette, P.O. Box 43602, Lafayette, Louisiana 70504;
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8
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Waddell JC, Caputi AA. Waveform discrimination in a pair of pulse-generating electric fishes. JOURNAL OF FISH BIOLOGY 2020; 96:1065-1071. [PMID: 32077109 DOI: 10.1111/jfb.14298] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 01/07/2020] [Accepted: 01/17/2020] [Indexed: 06/10/2023]
Abstract
Studies of pulse-type gymnotiform electric fishes have suggested that electric organ discharge waveforms (EODw) allow individuals to discriminate between conspecific and allospecific signals, but few have approached this experimentally. Here we implement a phase-locked playback technique for a syntopic species pair, Brachyhypopomus gauderio and Gymnotus omarorum. Both species respond to changes in stimulus waveform with a transitory reduction in the interpulse interval of their self-generated discharge, providing strong evidence of discrimination. We also document sustained rate changes in response to different EODws, which may suggest recognition of natural waveforms.
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Affiliation(s)
- Joseph C Waddell
- Department of Integrative and Computational Neurosciences, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - Angel A Caputi
- Department of Integrative and Computational Neurosciences, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
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Reproductive life-history strategies in a species-rich assemblage of Amazonian electric fishes. PLoS One 2019; 14:e0226095. [PMID: 31805125 PMCID: PMC6894849 DOI: 10.1371/journal.pone.0226095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 11/19/2019] [Indexed: 11/19/2022] Open
Abstract
The reproductive biology of only a small fraction of Neotropical freshwater fishes has been described, and detailed comparative studies of reproductive life-history variation in the Neotropical ichthyofauna are lacking. Here we describe interspecific variation in reproductive life history for a multi-species assemblage of the electric knifefish genus Brachyhypopomus (Hypopomidae: Gymnotiformes: Ostariophysi) from Amazonian floodplain and terra firme stream systems. During a year-round quantitative sampling program, we collected and measured key life-history traits from 3,410 individuals. Based on oocyte size distributions, and on circannual variation in gonadosomatic indices, hepatosomatic indices, and capture-per-unit-effort abundance of reproductive adults, we concluded that all species exhibit a single protracted annual breeding season during which females spawn fractionally. We found small clusters of post-larval individuals in one floodplain species and one terra firme stream species, but no signs of parental care. From analyses of body size-frequency distributions and otolith growth increments, we concluded that five species in our study area have approximately one-year (annual) semelparous life history with a single reproductive period followed by death, while two species have a two-year iteroparous life history, with breeding in both year-groups. Despite predictions from life-history theory we found no salient correlations between life history strategy (semelparity or iteroparity) and habitat occupancy (floodplain or terra firme stream). In the iteroparous species B. beebei, we documented evidence for reproductive restraint in the first breeding season relative to the second breeding season and argue that this is consistent with age-regulated terminal investment.
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Stoddard PK, Tran A, Krahe R. Predation and Crypsis in the Evolution of Electric Signaling in Weakly Electric Fishes. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00264] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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Crampton WGR. Electroreception, electrogenesis and electric signal evolution. JOURNAL OF FISH BIOLOGY 2019; 95:92-134. [PMID: 30729523 DOI: 10.1111/jfb.13922] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 02/05/2019] [Indexed: 05/06/2023]
Abstract
Electroreception, the capacity to detect external underwater electric fields with specialised receptors, is a phylogenetically widespread sensory modality in fishes and amphibians. In passive electroreception, a capacity possessed by c. 16% of fish species, an animal uses low-frequency-tuned ampullary electroreceptors to detect microvolt-range bioelectric fields from prey, without the need to generate its own electric field. In active electroreception (electrolocation), which occurs only in the teleost lineages Mormyroidea and Gymnotiformes, an animal senses its surroundings by generating a weak (< 1 V) electric-organ discharge (EOD) and detecting distortions in the EOD-associated field using high-frequency-tuned tuberous electroreceptors. Tuberous electroreceptors also detect the EODs of neighbouring fishes, facilitating electrocommunication. Several other groups of elasmobranchs and teleosts generate weak (< 10 V) or strong (> 50 V) EODs that facilitate communication or predation, but not electrolocation. Approximately 1.5% of fish species possess electric organs. This review has two aims. First, to synthesise our knowledge of the functional biology and phylogenetic distribution of electroreception and electrogenesis in fishes, with a focus on freshwater taxa and with emphasis on the proximate (morphological, physiological and genetic) bases of EOD and electroreceptor diversity. Second, to describe the diversity, biogeography, ecology and electric signal diversity of the mormyroids and gymnotiforms and to explore the ultimate (evolutionary) bases of signal and receptor diversity in their convergent electrogenic-electrosensory systems. Four sets of potential drivers or moderators of signal diversity are discussed. First, selective forces of an abiotic (environmental) nature for optimal electrolocation and communication performance of the EOD. Second, selective forces of a biotic nature targeting the communication function of the EOD, including sexual selection, reproductive interference from syntopic heterospecifics and selection from eavesdropping predators. Third, non-adaptive drift and, finally, phylogenetic inertia, which may arise from stabilising selection for optimal signal-receptor matching.
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Fronk AH, Kim LY, Craig JM, Crampton WGR, Albert JS. Sexual Size Dimorphism in the Macana Tigrina, Gymnotus javari (Gymnotidae, Gymnotiformes). COPEIA 2019. [DOI: 10.1643/ci-18-164] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Aaron H. Fronk
- Department of Biology, University of Louisiana at Lafayette, P.O. Box 43602, Lafayette, Louisiana 70504; (AHF) C00226417@louisiana. edu; and (JSA) . Send reprint requests to AHF
| | - Lesley Y. Kim
- Department of Biology, University of Louisiana at Lafayette, P.O. Box 43602, Lafayette, Louisiana 70504; (AHF) C00226417@louisiana. edu; and (JSA) . Send reprint requests to AHF
| | - Jack M. Craig
- Department of Biology, University of Louisiana at Lafayette, P.O. Box 43602, Lafayette, Louisiana 70504; (AHF) C00226417@louisiana. edu; and (JSA) . Send reprint requests to AHF
| | - William G. R. Crampton
- Department of Biology, University of Central Florida, Biological Sciences Bldg., 4110 Libra Drive, Orlando, Florida 32816-2368;
| | - James S. Albert
- Department of Biology, University of Louisiana at Lafayette, P.O. Box 43602, Lafayette, Louisiana 70504; (AHF) C00226417@louisiana. edu; and (JSA) . Send reprint requests to AHF
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13
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Caputi AA, Aguilera PA. Encoding phase spectrum for evaluating 'electric qualia'. ACTA ACUST UNITED AC 2019; 222:jeb.191544. [PMID: 30659081 DOI: 10.1242/jeb.191544] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 01/14/2019] [Indexed: 11/20/2022]
Abstract
The most broadly expressed and studied aspect of sensory transduction is receptor tuning to the power spectral density of the incoming signals. Temporal cues expressed in the phase spectrum are relevant in African and American pulse-emitting electric fish showing electroreceptors sensing the signals carried by the self- and conspecific-generated electric organ discharges. This article concerns the role of electroreceptor phase sensitivity in American pulse Gymnotiformes. These fish show electroreceptors sharply tuned to narrow frequency bands. This led to the common thought that most electrosensory information is contained in the amplitude spectra of the signals. However, behavioral and modeling studies suggest that in their pulses, Gymnotiformes electroreceptors also encode cues embodied in the phase spectrum of natural stimuli. Here, we show that the two main types of tuberous primary afferents of Gymnotus omarorum differentially respond to cues embodied in the amplitude and phase spectra of self-generated electrosensory signals. One afferent type, pulse markers, is mainly driven by the amplitude spectrum, while the other, burst coders, is predominantly sensitive to the phase spectrum. This dual encoding strategy allows the fish to create a sensory manifold where patterns of 'electric color' generated by object impedance and other potential sources of 'colored' images (such as large nearby objects and other electric fish) can be represented.
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Affiliation(s)
- Angel Ariel Caputi
- Departamento de Neurociencias Integrativas y Computacionales, Instituto de Investigaciones Biológicas Clemente Estable, CP 11600, Montevideo, Uruguay
| | - Pedro Aníbal Aguilera
- Departamento de Neurociencias Integrativas y Computacionales, Instituto de Investigaciones Biológicas Clemente Estable, CP 11600, Montevideo, Uruguay
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Rodríguez-Cattaneo A, Aguilera PA, Caputi AA. Waveform sensitivity of electroreceptors in the pulse-type weakly electric fish Gymnotus omarorum. ACTA ACUST UNITED AC 2017; 220:1663-1673. [PMID: 28202586 DOI: 10.1242/jeb.153379] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 02/13/2017] [Indexed: 11/20/2022]
Abstract
As in most sensory systems, electrosensory images in weakly electric fish are encoded in two parallel pathways, fast and slow. From work on wave-type electric fish, these fast and slow pathways are thought to encode the time and amplitude of electrosensory signals, respectively. The present study focuses on the primary afferents giving origin to the slow path of the pulse-type weakly electric fish Gymnotus omarorum We found that burst duration coders respond with a high-frequency train of spikes to each electric organ discharge. They also show high sensitivity to phase-frequency distortions of the self-generated local electric field. We explored this sensitivity by manipulating the longitudinal impedance of a probe cylinder to modulate the stimulus waveform, while extracellularly recording isolated primary afferents. Resistive loads only affect the amplitude of the re-afferent signals without distorting the waveform. Capacitive loads cause large waveform distortions aside from amplitude changes. Stepping from a resistive to a capacitive load in such a way that the stimulus waveform was distorted, without changing its total energy, caused strong changes in latency, inter-spike interval and number of spikes of primary afferent responses. These burst parameters are well correlated suggesting that they may contribute synergistically in driving downstream neurons. This correlation also suggests that each receptor encodes a single parameter in the stimulus waveform. The finding of waveform distortion sensitivity is relevant because it may contribute to: (a) enhance electroreceptive range in the peripheral 'electrosensory field', (b) a better identification of living prey at the 'foveal electrosensory field' and (c) detect the presence and orientation of conspecifics. Our results also suggest a revision of the classical view of amplitude and time encoding by fast and slow pathways in pulse-type electric fish.
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Affiliation(s)
- Alejo Rodríguez-Cattaneo
- Departamento de Neurociencias Integrativas y Computacionales, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, C.P 11600, Montevideo, Uruguay
| | - Pedro A Aguilera
- Departamento de Neurociencias Integrativas y Computacionales, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, C.P 11600, Montevideo, Uruguay
| | - Angel A Caputi
- Departamento de Neurociencias Integrativas y Computacionales, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, C.P 11600, Montevideo, Uruguay
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Phylogenetic Systematics, Biogeography, and Ecology of the Electric Fish Genus Brachyhypopomus (Ostariophysi: Gymnotiformes). PLoS One 2016; 11:e0161680. [PMID: 27736882 PMCID: PMC5063478 DOI: 10.1371/journal.pone.0161680] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 08/10/2016] [Indexed: 11/23/2022] Open
Abstract
A species-level phylogenetic reconstruction of the Neotropical bluntnose knifefish genus Brachyhypopomus (Gymnotiformes, Hypopomidae) is presented, based on 60 morphological characters, approximately 1100 base pairs of the mitochondrial cytb gene, and approximately 1000 base pairs of the nuclear rag2 gene. The phylogeny includes 28 species of Brachyhypopomus and nine outgroup species from nine other gymnotiform genera, including seven in the superfamily Rhamphichthyoidea (Hypopomidae and Rhamphichthyidae). Parsimony and Bayesian total evidence phylogenetic analyses confirm the monophyly of the genus, and identify nine robust species groups. Homoplastic osteological characters associated with diminutive body size and occurrence in small stream habitats, including loss of squamation and simplifications of the skeleton, appear to mislead a phylogenetic analysis based on morphological characters alone–resulting in the incorrect placing of Microsternarchus + Racenisia in a position deeply nested within Brachyhypopomus. Consideration of geographical distribution in light of the total evidence phylogeny indicates an origin for Brachyhypopomus in Greater Amazonia (the superbasin comprising the Amazon, Orinoco and major Guiana drainages), with subsequent dispersal and vicariance in peripheral basins, including the La Plata, the São Francisco, and trans-Andean basins of northwest South America and Central America. The ancestral habitat of Brachyhypopomus likely resembled the normoxic, low-conductivity terra firme stream system occupied by many extant species, and the genus has subsequently occupied a wide range of terra firme and floodplain habitats including low- and high-conductivity systems, and normoxic and hypoxic systems. Adaptations for impedance matching to high conductivity, and/or for air breathing in hypoxic systems have attended these habitat transitions. Several species of Brachyhypopomus are eurytopic with respect to habitat occupancy and these generally exhibit wider geographical ranges than stenotopic species.
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