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First published online July 26, 2004
Journal of Experimental Biology 207, 2907-2916 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.01126

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The electric fish Brachyhypopomus pinnicaudatus produces jamming avoidance responses to signals that are harmonically related to its own discharges

Alberto Capurro^1,2,* and Khashayar Pakdaman³

¹ Instituto de Física, Universidade de São Paulo (USP), Rua do Matão, Travessa R187, Cidade Universitaria, Butantã, 05508-900 São Paulo, Brasil
² Instituto de Investigaciones Biológicas Clemente Estable, Departamento de Neurofisiologia, Facultad de Ciencias, Avenida Italia 3318, Montevideo 11600, Uruguay
³ Institut Jacques Monod, CNRS, Universites Paris 6, Paris 7, 2 Place Jussieu, 75251 Paris Cedex 05, France

View larger version (54K): [in a new window]   Fig. 2. Jamming avoidance responses (JARs) in different settings or simulated. Interval and delay plots. (A,B) Female electric organ discharge (EOD) intervals are represented by circles; male EOD delay with respect to the female EOD are represented by asterisks plus lines. (A) Fish pair in laboratory settings (depicted in Fig. 1A). (B) Fish pair in natural environment (depicted in Fig. 1B). (C-F) Data generated numerically. Female train shown as interval vs time (circles); male train shown as delay vs time (asterisks plus lines). M*, mean interval in the absence of perturbations. (C) Data generated with model X attempting to mimic the situation in A; female faster train (M*=36.0 ms); male slower train (M*=36.5 ms). (D) Data generated with model Z attempting to mimic the situation in B. Female slower train (M*=36.0 ms); male faster train (M*=18.0 ms). (E) Data generated with model Z attempting to mimic the situation in A. Female faster train (M*=36.0 ms); male slower train (M*=36.5 ms). (F) Data generated with model Z attempting to mimic the situation in B. Female slower train (M*=36.0 ms); male faster train (M*=18.0 ms).

View larger version (17K): [in a new window]   Fig. 1. Jamming avoidance responses (JARs) in interacting pairs of Brachyhypopomus pinnicaudatus. Different pairs in A and B. Inter-EOD event intervals (ms) as a function of ongoing time (s). Female, red trace; male, blue trace. Mean intervals estimated from portions without transient interval shortenings. (A) Interval ratio of female to male close to 1:1 (in the laboratory). Mean intervals during the interaction: female, 19.5 ms; male, 20 ms. (B) Interval ratio of female to male close to 2:1 (natural environment). Mean intervals during the interaction: female, 36.0 ms; male, 18.0 ms.

View larger version (21K): [in a new window]   Fig. 3. Jamming avoidance responses (JARs) with 2:1 female:male period ratios: natural and simulated. Interval and delay plots. Fast male electric organ discharge (EOD) represented by intervals (circles); slow female EOD represented by its delay with respect to the male EOD (asterisks plus lines). (A) Fish pair in natural environment (same as in Fig. 2B). (B) Simulation using the incomplete version of model Z (same as in Fig. 2F). Male fast train (M*=18.0 ms); female slow train (M*=36.0 ms).

View larger version (86K): [in a new window]   Fig. 4. Jamming avoidance responses (JARs) and artificial pulses. Interval and delay plots. Isolated fish electric organ discharge (EOD) represented by intervals (circles); artificial pulses represented by delays relative to the EOD (asterisks with lines) and intervals (thick gray line). (A) 1:1 period ratio (male EOD). (B) 2:1 period ratio (male EOD). (C) JARs (female EOD) arise with 2:1 period ratios but not when those ratios vary because EOD intervals change. (D) JARs (male EOD) with 2:1 period ratios but not when those ratios vary because pulse intervals change. (E) 3:1 period ratio (female EOD). (F) Numerically generated data referring to the situation depicted in E. The slow train is plotted as interval vs time with black circles and represents the fish. The fast train represents the artificial pulses and is plotted both as delay vs time (asterisks plus lines) and as interval vs time (thick gray line). M* of the fast train=12.0 ms; M* of the slow train=36 ms.

View larger version (16K): [in a new window]   Fig. 5. Jamming avoidance responses (JARs) with 1:2 `electric organ discharge (EOD) to pulse' period ratios: natural and simulated. Interval and delay plots. EODs represented by intervals (black circles); artificial pulses represented by delays relative to the EOD (asterisks with lines). (A) Live fish: mean interval=68.0 ms; pulse interval=141.3 ms. (B) Failure of incomplete model Z, which responds only if pulses occur at consecutive sensitive windows. For B and C, fast train M*=36.0 ms; slow train M*=73.0 ms. (C) Success of complete model Z+, which responds to pulses arriving either at consecutive or every other sensitive window.