Intraspecific agonistic interactions in freely swimming mormyrid fish, Marcusenius macrolepidotus (South African form)

Werneyer, Martin; Krämer, Bernd J.

doi:10.1007/s10164-002-0062-y

Cited by 25 publications

(33 citation statements)

References 23 publications

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“…For example, a subordinate electric fish ceases its electric organ discharge for longer than 0.2 s when passing by the territory of a dominant conspecific (28)(29)(30)(31). Dolphins and whales can passively listen to echolocation signals of their companions to navigate and discriminate different objects (32)(33)(34).…”

Section: Discussionmentioning

confidence: 99%

Flying in silence: Echolocating bats cease vocalizing to avoid sonar jamming

Chiu

Xian

Moss

2008

Proc. Natl. Acad. Sci. U.S.A.

115

105

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Although it has been recognized that echolocating bats may experience jamming from the signals of conspecifics, research on this problem has focused exclusively on time-frequency adjustments in the emitted signals to minimize interference. Here, we report a surprising new strategy used by bats to avoid interference, namely silence. In a quantitative study of flight and vocal behavior of the big brown bat (Eptesicus fuscus), we discovered that the bat spends considerable time in silence when flying with conspecifics. Silent behavior, defined here as at least one bat in a pair ceasing vocalization for more than 0.2 s (200 ms), occurred as much as 76% of the time (mean of 40% across 7 pairs) when their separation was shorter than 1 m, but only 0.08% when a single bat flew alone. Spatial separation, heading direction, and similarity in call design of paired bats were related to the prevalence of this silent behavior. Our data suggest that the bat uses silence as a strategy to avoid interference from sonar vocalizations of its neighbor, while listening to conspecific-generated acoustic signals to guide orientation. Based on previous neurophysiological studies of the bat's auditory midbrain, we hypothesize that environmental sounds (including vocalizations produced by other bats) and active echolocation evoke neural activity in different populations of neurons. Our findings offer compelling evidence that the echolocating bat switches between active and passive sensing to cope with a complex acoustic environment, and these results hold broad implications for research on navigation and communication throughout the animal kingdom.echolocation ͉ jamming avoidance ͉ passive listening ͉ spatial hearing A ctive sensing enables a wide range of animal species to orient and forage under conditions where light levels are low or absent (1). Self-produced acoustic or electric signals give rise to information about the environment that is used to guide a variety of behaviors. Echolocating animals produce ultrasonic signals and determine the direction, distance, and features of objects in the environment from the arrival time, amplitude, and spectrum of sonar reflections (2). Electric fish generate discharges from an electric organ in the tail, and sense the location and features of nearby objects from amplitude and phase changes in the electric field (3).With the benefits of active sensing also come challenges, namely the potential for interference from signals produced by neighboring conspecifics. Past research has uncovered strategies by which echolocating bats and electric fish avoid jamming through active adjustments in the signals they produce to probe the environment. Wave-type weakly electric fish modify the electric organ discharge frequency, and pulse-type weakly electric fish change the timing of electric organ discharge to avoid interference from the signals of neighbors (3). In echolocating bats, spectral and/or temporal adjustments in the characteristics of sonar vocalizations, which yield acoustic separation between s...

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Section: Discussionmentioning

confidence: 99%

Flying in silence: Echolocating bats cease vocalizing to avoid sonar jamming

Chiu

Xian

Moss

2008

Proc. Natl. Acad. Sci. U.S.A.

115

105

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“…The IDI is highly variable both within and between species. Specific IDI patterns are correlated with certain overt behavioural patterns (Bauer 1972;Bell et al 1974;Kramer 1974Kramer , 1976Kramer and Bauer 1976;Scheffel and Kramer 1997;Werneyer and Kramer 2002). Möhres (1957), Lissmann (1958) and Szabo (in Lissmann 1961) suggested a communication function of EOD and IDI pattern, which was confirmed much later when electrocommunication was studied mainly in Gnathonemus petersii (e.g., Bauer 1973;Bell et al 1974;Kramer 1974), and in Pollimyrus adspersus (Bratton and Kramer 1989).…”

Section: Introductionmentioning

confidence: 87%

“…They originated from a group of M. macrolepidotus that were caught in 1997 in the Crocodile River, Mpumalanga Province, South Africa, and immediately exported to Germany where we kept them in our aquaria (for further information, see Werneyer and Kramer 2002). In December 1999 and March 2001, standard lengths (SL) were 15.5 and 16 cm for the female, and 21.6 and 21.7 cm for the male (as determined from photographs).…”

Section: Methodsmentioning

confidence: 99%

“…During behavioural observations, EODs were recorded simultaneously from four pairs of carbon electrodes fixed on the aquarium walls (for details of arrangement, see Werneyer and Kramer 2002). The potential difference was separately amplified (GVJ, GV3, Elektronische Werkstätten der Universität Regensburg) and separately recorded on four channels of an eight-channel instrumentation tape recorder (Racal StorePlus, Racal Recorders).…”

Section: Methodsmentioning

confidence: 99%

“…IDI histograms were calculated using a geometrical progression of bin width with interval duration, as introduced by Graff (1989) and also used by Werneyer and Kramer (2002). In the present study a bin is referred to by its centre.…”

Section: Methodsmentioning

confidence: 99%

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Electric signalling and reproductive behaviour in a mormyrid fish, the bulldog Marcusenius macrolepidotus (South African form)

Werneyer

Krämer

2005

J Ethol

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Bulldog fish (Marcusenius macrolepidotus) generate short (<1 ms) electric-organ discharges (EODs), separated by much longer and highly variable interdischarge intervals (IDIs). We observed overt behaviour and electrical activity during reproductive behaviour in a male and in a female bulldog, and identified IDI patterns with putative signal functions. In contrast to Pollimyrus adspersus and Pollimyrus isidori, in which an elaborate and extended courtship precedes spawning proper, our fish started spawning almost immediately when we allowed the female to enter the male's territory. The male did not construct a nest, and neither parent provided parental care. The male showed very little aggression towards the intruding female. Fish spawned in bouts near the male's hiding place, and eggs were scattered by the female's vigorous tail flips as she left the spawning site, only to return shortly thereafter. During spawning bouts, both fish generated highly stereotyped IDI patterns: the male generated a series of IDIs gradually decreasing from about 200 ms to about 55 ms that was abruptly terminated by a long IDI. The female generated a series of relatively regular IDIs (about 54 ms) that was followed by a marked increase in IDI duration (the probable time of spawning). Finally, a sharp decrease in IDIs to about 20 ms accompanied the female's sudden escape from the spawning site. In between spawning bouts, both fish generated series of very short IDIs (high discharge rate, HD) that alternated abruptly with very low-rate inter-HD activity (especially in the male). IDIs as short as 9 ms (male) or 11 ms (female) occurred during HD displays. No visible aggression, in fact very little overt behaviour, occurred during these HD displays in both fish. Agonistic interactions between male and female, outside a reproductive context, were similar to those previously described in male pairs, including overt behavioural patterns such as parallel swimming, antiparallel display and attack, as well as HD displays. When not interacting, fish did not generate HD displays. We suggest the HD display is a communication signal in both reproductive and agonistic contexts.

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