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Hauser FE, Xiao D, Van Nynatten A, Brochu-De Luca KK, Rajakulendran T, Elbassiouny AE, Sivanesan H, Sivananthan P, Crampton WGR, Lovejoy NR. Ecologically mediated differences in electric organ discharge drive evolution in a sodium channel gene in South American electric fishes. Biol Lett 2024; 20:20230480. [PMID: 38412964 PMCID: PMC10898970 DOI: 10.1098/rsbl.2023.0480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 01/29/2024] [Indexed: 02/29/2024] Open
Abstract
Active electroreception-the ability to detect objects and communicate with conspecifics via the detection and generation of electric organ discharges (EODs)-has evolved convergently in several fish lineages. South American electric fishes (Gymnotiformes) are a highly species-rich group, possibly in part due to evolution of an electric organ (EO) that can produce diverse EODs. Neofunctionalization of a voltage-gated sodium channel gene accompanied the evolution of electrogenic tissue from muscle and resulted in a novel gene (scn4aa) uniquely expressed in the EO. Here, we investigate the link between variation in scn4aa and differences in EOD waveform. We combine gymnotiform scn4aa sequences encoding the C-terminus of the Nav1.4a protein, with biogeographic data and EOD recordings to test whether physiological transitions among EOD types accompany differential selection pressures on scn4aa. We found positive selection on scn4aa coincided with shifts in EOD types. Species that evolved in the absence of predators, which likely selected for reduced EOD complexity, exhibited increased scn4aa evolutionary rates. We model mutations in the protein that may underlie changes in protein function and discuss our findings in the context of gymnotiform signalling ecology. Together, this work sheds light on the selective forces underpinning major evolutionary transitions in electric signal production.
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Affiliation(s)
- Frances E. Hauser
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
| | - Dawn Xiao
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
| | - Alexander Van Nynatten
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord St, Toronto, Ontario, Canada M5S 3G5
| | - Kristen K. Brochu-De Luca
- Department of Entomology, Pennsylvania State University, 501 ASI Building, University Park, PA 16802, USA
- School of Chemistry, Environmental and Life Sciences, University of The Bahamas, Oakes Field Campus, Nassau, New Providence, The Bahamas
| | - Thanara Rajakulendran
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
| | - Ahmed E. Elbassiouny
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord St, Toronto, Ontario, Canada M5S 3G5
| | - Harunya Sivanesan
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
| | - Pradeega Sivananthan
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
| | - William G. R. Crampton
- Department of Biology, University of Central Florida, 4110 Libra Dr, Orlando, FL 32816, USA
| | - Nathan R. Lovejoy
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord St, Toronto, Ontario, Canada M5S 3G5
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St, Toronto, Ontario, Canada M5S 3B2
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Cheng F, Dennis AB, Baumann O, Kirschbaum F, Abdelilah-Seyfried S, Tiedemann R. Gene and Allele-Specific Expression Underlying the Electric Signal Divergence in African Weakly Electric Fish. Mol Biol Evol 2024; 41:msae021. [PMID: 38410843 PMCID: PMC10897887 DOI: 10.1093/molbev/msae021] [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: 10/31/2023] [Revised: 12/15/2023] [Accepted: 01/29/2024] [Indexed: 02/28/2024] Open
Abstract
In the African weakly electric fish genus Campylomormyrus, electric organ discharge signals are strikingly different in shape and duration among closely related species, contribute to prezygotic isolation, and may have triggered an adaptive radiation. We performed mRNA sequencing on electric organs and skeletal muscles (from which the electric organs derive) from 3 species with short (0.4 ms), medium (5 ms), and long (40 ms) electric organ discharges and 2 different cross-species hybrids. We identified 1,444 upregulated genes in electric organ shared by all 5 species/hybrid cohorts, rendering them candidate genes for electric organ-specific properties in Campylomormyrus. We further identified several candidate genes, including KCNJ2 and KLF5, and their upregulation may contribute to increased electric organ discharge duration. Hybrids between a short (Campylomormyrus compressirostris) and a long (Campylomormyrus rhynchophorus) discharging species exhibit electric organ discharges of intermediate duration and showed imbalanced expression of KCNJ2 alleles, pointing toward a cis-regulatory difference at this locus, relative to electric organ discharge duration. KLF5 is a transcription factor potentially balancing potassium channel gene expression, a crucial process for the formation of an electric organ discharge. Unraveling the genetic basis of the species-specific modulation of the electric organ discharge in Campylomormyrus is crucial for understanding the adaptive radiation of this emerging model taxon of ecological (perhaps even sympatric) speciation.
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Affiliation(s)
- Feng Cheng
- Unit of Evolutionary Biology/Systematic Zoology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Alice B Dennis
- Unit of Evolutionary Biology/Systematic Zoology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
- Laboratory of Adaptive Evolution and Genomics, Research Unit of Environmental and Evolutionary Biology, Institute of Life, Earth & Environment, University of Namur, Namur, Belgium
| | - Otto Baumann
- Department of Animal Physiology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Frank Kirschbaum
- Unit of Evolutionary Biology/Systematic Zoology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
- Department of Crop and Animal Science, Faculty of Life Sciences, Humboldt University, Berlin, Germany
| | - Salim Abdelilah-Seyfried
- Department of Animal Physiology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
| | - Ralph Tiedemann
- Unit of Evolutionary Biology/Systematic Zoology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany
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Losilla M, Gallant JR. Molecular evolution of the ependymin-related gene epdl2 in African weakly electric fish. G3 (BETHESDA, MD.) 2023; 13:6931758. [PMID: 36529459 PMCID: PMC9997568 DOI: 10.1093/g3journal/jkac331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 11/01/2022] [Accepted: 11/16/2022] [Indexed: 12/23/2022]
Abstract
Gene duplication and subsequent molecular evolution can give rise to taxon-specific gene specializations. In previous work, we found evidence that African weakly electric fish (Mormyridae) may have as many as three copies of the epdl2 gene, and the expression of two epdl2 genes is correlated with electric signal divergence. Epdl2 belongs to the ependymin-related family (EPDR), a functionally diverse family of secretory glycoproteins. In this study, we first describe vertebrate EPDR evolution and then present a detailed evolutionary history of epdl2 in Mormyridae with emphasis on the speciose genus Paramormyrops. Using Sanger sequencing, we confirm three apparently functional epdl2 genes in Paramormyrops kingsleyae. Next, we developed a nanopore-based amplicon sequencing strategy and bioinformatics pipeline to obtain and classify full-length epdl2 gene sequences (N = 34) across Mormyridae. Our phylogenetic analysis proposes three or four epdl2 paralogs dating from early Paramormyrops evolution. Finally, we conducted selection tests which detected positive selection around the duplication events and identified ten sites likely targeted by selection in the resulting paralogs. These sites' locations in our modeled 3D protein structure involve four sites in ligand binding and six sites in homodimer formation. Together, these findings strongly imply an evolutionary mechanism whereby epdl2 genes underwent selection-driven functional specialization after tandem duplications in the rapidly speciating Paramormyrops. Considering previous evidence, we propose that epdl2 may contribute to electric signal diversification in mormyrids, an important aspect of species recognition during mating.
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Affiliation(s)
- Mauricio Losilla
- Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, USA.,Graduate Program in Ecology, Evolution and Behavior, Michigan State University, East Lansing, MI 48824, USA
| | - Jason R Gallant
- Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, USA.,Graduate Program in Ecology, Evolution and Behavior, Michigan State University, East Lansing, MI 48824, USA
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Dunlap KD, Koukos HM, Chagnaud BP, Zakon HH, Bass AH. Vocal and Electric Fish: Revisiting a Comparison of Two Teleost Models in the Neuroethology of Social Behavior. Front Neural Circuits 2021; 15:713105. [PMID: 34489647 PMCID: PMC8418312 DOI: 10.3389/fncir.2021.713105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 07/12/2021] [Indexed: 11/30/2022] Open
Abstract
The communication behaviors of vocal fish and electric fish are among the vertebrate social behaviors best understood at the level of neural circuits. Both forms of signaling rely on midbrain inputs to hindbrain pattern generators that activate peripheral effectors (sonic muscles and electrocytes) to produce pulsatile signals that are modulated by frequency/repetition rate, amplitude and call duration. To generate signals that vary by sex, male phenotype, and social context, these circuits are responsive to a wide range of hormones and neuromodulators acting on different timescales at multiple loci. Bass and Zakon (2005) reviewed the behavioral neuroendocrinology of these two teleost groups, comparing how the regulation of their communication systems have both converged and diverged during their parallel evolution. Here, we revisit this comparison and review the complementary developments over the past 16 years. We (a) summarize recent work that expands our knowledge of the neural circuits underlying these two communication systems, (b) review parallel studies on the action of neuromodulators (e.g., serotonin, AVT, melatonin), brain steroidogenesis (via aromatase), and social stimuli on the output of these circuits, (c) highlight recent transcriptomic studies that illustrate how contemporary molecular methods have elucidated the genetic regulation of social behavior in these fish, and (d) describe recent studies of mochokid catfish, which use both vocal and electric communication, and that use both vocal and electric communication and consider how these two systems are spliced together in the same species. Finally, we offer avenues for future research to further probe how similarities and differences between these two communication systems emerge over ontogeny and evolution.
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Affiliation(s)
- Kent D Dunlap
- Department of Biology, Trinity College, Hartford, CT, United States
| | - Haley M Koukos
- Department of Biology, Trinity College, Hartford, CT, United States
| | - Boris P Chagnaud
- Institute of Biology, Karl-Franzens-University Graz, Graz, Austria
| | - Harold H Zakon
- Department of Neuroscience, University of Texas at Austin, Austin, TX, United States.,Department of Integrative Biology, University of Texas at Austin, Austin, TX, United States
| | - Andrew H Bass
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, United States
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Korniienko Y, Tiedemann R, Vater M, Kirschbaum F. Ontogeny of the electric organ discharge and of the papillae of the electrocytes in the weakly electric fish Campylomormyrus rhynchophorus (Teleostei: Mormyridae). J Comp Neurol 2021; 529:1052-1065. [PMID: 32785950 DOI: 10.1002/cne.25003] [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: 09/30/2019] [Revised: 07/28/2020] [Accepted: 08/06/2020] [Indexed: 11/11/2022]
Abstract
The electric organ of the mormyrid weakly electric fish, Campylomormyrus rhynchophorus (Boulenger, 1898), undergoes changes in both the electric organ discharge (EOD) and the light and electron microscopic morphology as the fish mature from the juvenile to the adult form. Of particular interest was the appearance of papillae, surface specializations of the uninnervated anterior face of the electrocyte, which have been hypothesized to increase the duration of the EOD. In a 24.5 mm long juvenile the adult electric organ (EO) was not yet functional, and the electrocytes lacked papillae. A 40 mm long juvenile, which produced a short biphasic EOD of 1.3 ms duration, shows small papillae (average area 136 μm2 ). In contrast, the EOD of a 79 mm long juvenile was triphasic. The large increase in duration of the EOD to 23.2 ms was accompanied by a small change in size of the papillae (average area 159 μm2 ). Similarly, a 150 mm long adult produced a triphasic EOD of comparable duration to the younger stage (24.7 ms) but featured a prominent increase in size of the papillae (average area 402 μm2 ). Thus, there was no linear correlation between EOD duration and papillary size. The most prominent ultrastructural change was at the level of the myofilaments, which regularly extended into the papillae, only in the oldest specimen-probably serving a supporting function. Physiological mechanisms, like gene expression levels, as demonstrated in some Campylomormyrus species, might be more important concerning the duration of the EOD.
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Affiliation(s)
- Yevheniia Korniienko
- Humboldt University of Berlin, Faculty of Life Sciences, Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, Unit of Biology and Ecology of Fishes, Berlin, Germany
| | - Ralph Tiedemann
- University of Potsdam, Institute of Biochemistry and Biology, Unit of Evolutionary Biology / Systematic Zoology, Potsdam-Golm, Germany
| | - Marianne Vater
- Unit of General Zoology, Institute of Biochemistry and Biology, University of Potsdam, Potsdam Golm, Germany
| | - Frank Kirschbaum
- Humboldt University of Berlin, Faculty of Life Sciences, Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, Unit of Biology and Ecology of Fishes, Berlin, Germany
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