The Effect of male-male competition and its Underlying Regulatory Mechanisms on the Electric Signal of the Gymnotiform fish &lt;em&gt;Brachyhypopomus gauderio&lt;/em&gt;

Salazar, Vielka L.

doi:10.25148/etd.fi09120802

Cited by 3 publications

(5 citation statements)

References 119 publications

(130 reference statements)

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“…In the lab, females select longer males, which typically produce EODs of greater amplitude and duration (Curtis & Stoddard 2003). Moreover, in staged resident-intruder contests, the longest male always won the encounter despite residential status or body condition (Salazar 2009; Silva et al 2010). From the tight relationship between body length and EOD amplitude, a receiver could use the amplitude of the signaller’s EOD as an indicator of his resource holding potential.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, the EOD of B. gauderio has the potential to serve as an indicator of body length since the amplitude of the signal physically depends on the length of the electric organ, which runs the length of the fish’s body (Curtis & Stoddard 2003; Hopkins et al 1990; Hopkins 1999). Body length information is relevant for mate-choice and male-male interactions, since longer males are more attractive to females (Curtis & Stoddard 2003) and more likely to win agonistic encounters (Salazar 2009; Silva et al 2010). Additionally, electric signals of males are costly handicaps; they are energetically expensive, consuming an average of 22% of the daily energetic budget (compared to 3% for females), and their energetic costs rise with the amplitude of the EOD (Salazar & Stoddard 2008).…”

Section: Introductionmentioning

confidence: 99%

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Signal modulation as a mechanism for handicap disposal

et al. 2012

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Signal honesty may be compromised when heightened competition provides incentive for signal exaggeration. Some degree of honesty might be maintained by intrinsic handicap costs on signalling or through imposition of extrinsic costs, such as social punishment of low quality cheaters. Thus, theory predicts a delicate balance between signal enhancement and signal reliability that varies with degree of social competition, handicap cost, and social cost. We investigated whether male sexual signals of the electric fish Brachyhypopomus gauderio would become less reliable predictors of body length when competition provides incentives for males to boost electric signal amplitude. As expected, social competition under natural field conditions and in controlled lab experiments drove males to enhance their signals. However, signal enhancement improved the reliability of the information conveyed by the signal, as revealed in the tightening of the relationship between signal amplitude and body length. Signal augmentation in male B. gauderio was independent of body length, and thus appeared not to be curtailed through punishment of low quality (small) individuals. Rather, all individuals boosted their signals under high competition, but those whose signals were farthest from the predicted value under low competition boosted signal amplitude the most. By elimination, intrinsic handicap cost of signal production, rather than extrinsic social cost, appears to be the basis for the unexpected reinforcement of electric signal honesty under social competition. Signal modulation may provide its greatest advantage to the signaller as a mechanism for handicap disposal under low competition rather than as a mechanism for exaggeration of quality under high competition.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Signal modulation as a mechanism for handicap disposal

et al. 2012

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“…Body length is tightly related to EOD amplitude, and this relationship improves as EOD amplitude increases during competition as males signal the closest to their physiological limit (Gavassa et al 2012). Body size information is key for mate choice and male-male aggression; longer males are preferred by females (Curtis and Stoddard 2003) and are more likely to win an agonistic encounter (Salazar 2009;Silva et al, unpublished). On the other hand, signal duration in males and females conveys information about the reproductive state of the signaler and possibly its aggressive intent .…”

Section: Discussionmentioning

confidence: 92%

“…EOD amplitude enhancements may signal resource holding potential under social competition (Salazar 2009;Silva et al, unpublished;Gavassa et al 2012) or may improve electrolocation by overcoming the increase in background noise that results from greater population density. Both field and lab studies provided strong evidence that females increase τ P2 with female intrasexual competition.…”

Section: Discussionmentioning

confidence: 97%

Social competition masculinizes the communication signals of female electric fish

Gavasa

Silva

González

et al. 2012

Behav Ecol Sociobiol

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Male intrasexual competition and female choice explain the evolution of male ornaments. Except in sex-rolereversed taxa, female ornaments have been regarded as an epiphenomenon of genetic correlation, with no femalespecific function or independently selected basis. Females from species with conventional sex roles may still experience some degree of female-female competition and male choice that could explain the persistence of female ornaments. We studied the effect of female competition on the expression of a sexually dimorphic communication signal. In the electric fish Brachyhypopomus gauderio, both sexes produce an electric signal pulse for communication and electrolocation. Male electric pulses are longer in duration and greater in amplitude than those of females. As competition increases, males further enhance their signals in response to elevated androgen levels. We explored whether females respond to social competition as males do, by enhancing their communication signals and increasing androgen levels. We measured amplitude and duration of the electric signal pulse, and testosterone levels in female B. gauderio in their natural habitat in Uruguay and estimated social competition by calculating population density and adult sex ratio (ASR). In the lab, we manipulated ASR and population density independently to separate these factors and eliminate seasonal confounds. Under both field and lab conditions, signal pulse amplitude increased with population density, while pulse duration increased with female bias in ASR. In the field, but not the lab, androgen levels increased when ASR was female biased. Our findings indicate that the socially mediated mechanism of signal regulation is shared by the sexes, although whether androgens regulate this signal plasticity in females remains unclear.

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“…The EOD of B. gauderio could serve as an indicator of body length because the amplitude of the signal physically depends on the length of the electric organ, which runs the length of the fish's body (Curtis and Stoddard, 2003;Hopkins, 1999;Hopkins et al, 1990). Moreover, body length is key for mate choice and male-male interactions, as longer males are more attractive to females (Curtis and Stoddard, 2003) and are more likely to win agonistic encounters (Salazar, 2009;Zubizarreta et al, 2012). Therefore, receivers should pay particular attention to any information about body length coded in the signal.…”

Section: Does Eod Modulation Degrade Its Reliability As An Honest Indmentioning

confidence: 99%

Behavioral ecology, endocrinology and signal reliability of electric communication

Gavassa

Goldina

Silva

et al. 2013

Journal of Experimental Biology

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SummaryThe balance between the costs and benefits of conspicuous animal communication signals ensures that signal expression relates to the quality of the bearer. Signal plasticity enables males to enhance conspicuous signals to impress mates and competitors and to reduce signal expression to lower energetic and predation-related signaling costs when competition is low. While signal plasticity may benefit the signaler, it can compromise the reliability of the information conveyed by the signals. In this paper we review the effect of signal plasticity on the reliability of the electrocommunication signal of the gymnotiform fish Brachyhypopomus gauderio. We (1) summarize the endocrine regulation of signal plasticity, (2) explore the regulation of signal plasticity in females, (3) examine the information conveyed by the signal, (4) show how that information changes when the signal changes, and (5) consider the energetic strategies used to sustain expensive signaling. The electric organ discharge (EOD) of B. gauderio changes in response to social environment on two time scales. Two hormone classes, melanocortins and androgens, underlie the short-term and long-term modulation of signal amplitude and duration observed during social interaction. Population density drives signal amplitude enhancement, unexpectedly improving the reliability with which the signal predicts the signalerʼs size. The signalʼs second phase elongation predicts androgen levels and male reproductive condition. Males sustain signal enhancement with dietary intake, but when food is limited, they ʻgo for brokeʼ and put extra energy into electric signals. Cortisol diminishes EOD parameters, but energy-limited males offset cortisol effects by boosting androgen levels. While physiological constraints are sufficient to maintain signal amplitude reliability, phenotypic integration and signaling costs maintain reliability of signal duration, consistent with theory of honest signaling. on the reliability of the information conveyed by the signal. In this paper, we (1) discuss the endocrine mechanisms that regulate signal plasticity in males, (2) explore whether those mechanisms are also present in females, (3) examine the information conveyed by the signal, (4) examine how that information changes when the signal changes, and finally (5) consider the energetic strategies used to sustain expensive signaling.

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The Effect of male-male competition and its Underlying Regulatory Mechanisms on the Electric Signal of the Gymnotiform fish <em>Brachyhypopomus gauderio</em>

Cited by 3 publications

References 119 publications

Signal modulation as a mechanism for handicap disposal

Signal modulation as a mechanism for handicap disposal

Social competition masculinizes the communication signals of female electric fish

Behavioral ecology, endocrinology and signal reliability of electric communication

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