Electric fishes: neural systems, behaviour and evolution

Krahe, Rüdiger; Fortune, Eric S.

doi:10.1242/jeb.091322

Cited by 13 publications

(16 citation statements)

References 21 publications

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“…The neural circuits that control the production and reception of these signals are well described (Berman and Maler, 1999; Carr and Maler, 1986; Heiligenberg et al, 1996; Metzner, 1999; Smith, 1999), and the signals are diverse both across and within species (Crampton, 1998; Crampton and Albert, 2006; Crampton et al, 2011; Hopkins, 1988; Kramer et al, 1981; Turner et al, 2007). Gymnotiform fishes have consequently become an established neuroethological model for comparative studies of the evolution and physiology of communication, sex differences, and sensory biology (Dulka, 1997; Dulka and Ebling, 1999; Hopkins, 1988; Krahe and Fortune, 2013; Krahe and Maler, 2014; Meyer et al, 1987; Smith, 1999; Turner et al, 2007; Zakon et al, 1999). …”

Section: Introductionmentioning

confidence: 99%

Evolution of electric communication signals in the South American ghost knifefishes (Gymnotiformes: Apteronotidae): A phylogenetic comparative study using a sequence-based phylogeny

Smith¹,

Proffitt²,

Ho³

et al. 2016

Journal of Physiology-Paris

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The electric communication signals of weakly electric ghost knifefishes (Gymnotiformes: Apteronotidae) provide a valuable model system for understanding the evolution and physiology of behavior. Apteronotids produce continuous wave-type electric organ discharges (EODs) that are used for electrolocation and communication. The frequency and waveform of EODs, as well as the structure of transient EOD modulations (chirps), vary substantially across species. Understanding how these signals have evolved, however, has been hampered by the lack of a well-supported phylogeny for this family. We constructed a molecular phylogeny for the Apteronotidae by using sequence data from three genes (cytochrome c oxidase subunit 1, recombination activating gene 2, and cytochrome oxidase B) in 32 species representing 13 apteronotid genera. This phylogeny and an extensive database of apteronotid signals allowed us to examine signal evolution by using ancestral state reconstruction (ASR) and phylogenetic generalized least squares (PGLS) models. Our molecular phylogeny largely agrees with another recent sequence-based phylogeny and identified five robust apteronotid clades: (i) Sternarchorhamphus + Orthosternarchus, (ii) Adontosternarchus, (iii) Apteronotus + Parapteronotus, (iv) Sternarchorhynchus, and (v) a large clade including Porotergus, ‘Apteronotus’, Compsaraia, Sternarchogiton, Sternarchella, and Magosternarchus. We analyzed novel chirp recordings from two apteronotid species (Orthosternarchus tamandua and Sternarchorhynchus mormyrus), and combined data from these species with that from previously recorded species in our phylogenetic analyses. Some signal parameters in O. tamandua were plesiomorphic (e.g., low frequency EODs and chirps with little frequency modulation that nevertheless interrupt the EOD), suggesting that ultra-high frequency EODs and ‘‘big” chirps evolved after apteronotids diverged from other gymnotiforms. In contrast to previous studies, our PGLS analyses using the new phylogeny indicated the presence of phylogenetic signals in the relationships between some EOD and chirp parameters. The ASR demonstrated that most EOD and chirp parameters are evolutionarily labile and have often diversified even among closely related species.

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Section: Introductionmentioning

confidence: 99%

Evolution of electric communication signals in the South American ghost knifefishes (Gymnotiformes: Apteronotidae): A phylogenetic comparative study using a sequence-based phylogeny

Smith¹,

Proffitt²,

Ho³

et al. 2016

Journal of Physiology-Paris

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“…). In addition to the well‐known suitability of gymnotiforms as neuroethological model systems (Krahe & Fortune ), the non‐breeding territorial aggression of G. omarorum offers a convenient experimental model to study the decision‐making process during an agonistic encounter. Subordinate fish perform three behaviors on the pathway to submission that reflect the decisions made: They interrupt their EOD, stop attacking and retreat, and emit ‘chirp’ signals (Batista et al.…”

Section: Introductionmentioning

confidence: 99%

“…Subordinates modulate their EOD rate during agonistic interactions: EOD interruptions ('off' signals) are produced early in the contest, while chirps (brief EOD rate increases with waveform distortion) are emitted as post-resolution subordination signals (Batista et al 2012). In addition to the well-known suitability of gymnotiforms as neuroethological model systems (Krahe & Fortune 2013), the non-breeding territorial aggression of G. omarorum offers a convenient experimental model to study the decision-making process during an agonistic encounter. Subordinate fish perform three behaviors on the pathway to submission that reflect the decisions made: They interrupt their EOD, stop attacking and retreat, and emit 'chirp' signals (Batista et al 2012;Silva et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Aggression Levels Affect Social Interaction in the Non‐Breeding Territorial Aggression of the Weakly Electric Fish, Gymnotus omarorum

2014

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Animals typically decide whether to fight or retreat from conspecifics based on their individual estimates of the costs and benefits of fighting. Theoretical models predict how contenders solve a conflict, but the evaluation processes involved in these decisions depend on multiple factors that are difficult to explore experimentally. We addressed these questions using the non-breeding territorial aggression of Gymnotus omarorum, in which subordinates make three distinctive decisions to signal their submission during a fight: (1) interruption of their electric discharges to hide from the dominant, (2) stop attacking and retreat, and (3) emission of 'chirps', transient submissive electric signals. We confirmed that subordinates take into account the aggressive performance of dominants to shape their own agonistic decisions and performance. The intensity of aggression is highly correlated with an agonistic dyad, and the decision of subordinates to retreat is influenced by the attack rates of dominants. When we lowered the aggression of expected dominants with a 5-HT 1A receptor agonist, the correlation between the two contenders' aggression levels was lost and subordinates completely stopped emitting electric chirp signals. The aforementioned results contribute to the understanding of the decision-making strategies driven by social challenge inherent to agonistic encounters.

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“…1A). These knifefish are important model systems for studying sensory neurobiology (Turner et al, 1999;Krahe and Fortune, 2013) and sensory motor integration (Snyder et al, 2007;MacIver et al, 2010;Cowan and Fortune, 2007). Furthermore, research on the unique biomechanics and sensory modality of electric knifefish has inspired the design of numerous underwater robots capable of agile movement and omnidirectional close-range sensing (reviewed by Neveln et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Undulating fins produce off-axis thrust and flow structures

Neveln

Bale

Bhalla

et al. 2013

Journal of Experimental Biology

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While wake structures of many forms of swimming and flying are well characterized, the wake generated by a freely swimming undulating fin has not yet been analyzed. These elongated fins allow fish to achieve enhanced agility exemplified by the forward, backward and vertical swimming capabilities of knifefish, and also have potential applications in the design of more maneuverable underwater vehicles. We present the flow structure of an undulating robotic fin model using particle image velocimetry to measure fluid velocity fields in the wake. We supplement the experimental robotic work with highfidelity computational fluid dynamics, simulating the hydrodynamics of both a virtual fish, whose fin kinematics and fin plus body morphology are measured from a freely swimming knifefish, and a virtual rendering of our robot. Our results indicate that a series of linked vortex tubes is shed off the long edge of the fin as the undulatory wave travels lengthwise along the fin. A jet at an oblique angle to the fin is associated with the successive vortex tubes, propelling the fish forward. The vortex structure bears similarity to the linked vortex ring structure trailing the oscillating caudal fin of a carangiform swimmer, though the vortex rings are distorted because of the undulatory kinematics of the elongated fin.

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Electric fishes: neural systems, behaviour and evolution

Cited by 13 publications

References 21 publications

Evolution of electric communication signals in the South American ghost knifefishes (Gymnotiformes: Apteronotidae): A phylogenetic comparative study using a sequence-based phylogeny

Evolution of electric communication signals in the South American ghost knifefishes (Gymnotiformes: Apteronotidae): A phylogenetic comparative study using a sequence-based phylogeny

Aggression Levels Affect Social Interaction in the Non‐Breeding Territorial Aggression of the Weakly Electric Fish, Gymnotus omarorum

Undulating fins produce off-axis thrust and flow structures

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