Journal of Comparative Physiology A

, Volume 199, Issue 5, pp 375–384 | Cite as

Social regulation of electric signal plasticity in male Brachyhypopomus gauderio

  • Sat Gavassa
  • James P. Roach
  • Philip K. Stoddard
Original Paper


In animal communication, the social context that elicits particular dynamic changes in the signal can provide indirect clues to signal function. Female presence should increase the expression of male signal traits relevant for mate-choice, while male presence should promote the enhancement of traits involved in male-male competition. The electric fish Brachyhypopomus gauderio produces a biphasic electric pulse for electrolocation and communication. Pulse amplitude predicts the signaler’s body size while pulse duration predicts circulating androgen levels. Males enhance pulse amplitude and duration when the numbers of males and females increase simultaneously. Here we tested the relative effects of female presence and male presence on male signal enhancement, and whether the size of the male competitor affected this enhancement. We found that male presence drives the enhancement of both pulse amplitude and second phase duration, independently of the size of the male competitor. Female presence induces the enhancement of pulse duration, but not pulse amplitude. These data suggest that males probably attend to information about a competitor’s body size coded by pulse amplitude and attend to aggressiveness coded by a competitor’s pulse duration, both potential predictors of fight outcome. Females may be primarily concerned about information on reproductive condition coded by pulse duration.


Electric fish Animal communication Signal plasticity Male-male competition Female choice 



Adrenocorticotropic hormone


α-melanocyte stimulating hormone


Electric organ discharge


Second phase of the electric organ discharge


Time constant of second phase repolarization


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Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Sat Gavassa
    • 1
  • James P. Roach
    • 1
  • Philip K. Stoddard
    • 1
  1. 1.Department of Biological Sciences, OE-167Florida International UniversityMiamiUSA

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