Data from: Rapid effects of elevated stress hormones on male courtship signals suggest a major role for the acute stress response in intra- and intersexual selection

1. Short-term elevations in circulating stress hormones (glucocorticoids) often mediate reduced investment in reproductive behavior in favor of self-maintenance and survival, but the significance of these effects in sexual selection and communication remain largely unexplored. 2. Here we examine the acute stress response in the context of intra- and intersexual selection in the green treefrog, Hyla cinerea. Males of this species produce agonistic acoustic signals that stimulate elevations in the stress hormone corticosterone (CORT) in rival males, suggesting a central role for CORT in male-male competition. We hypothesized that elevated CORT levels in losers of vocal contests mediate an increase in the energy allocated towards self-maintenance and survival that compromises investment in courtship signaling, resulting in reduced attractiveness to females. 3. Consistent with this hypothesis, we show that CORT administration to calling males, simulating CORT production in vocal contest losers, caused a rapid reduction in the duration of advertisement calls and vocal effort. Elevated CORT also increased the propensity to produce aggressive calls during simulated territorial intrusions that was followed by an increased probability of non-calling “satellite” mating behavior. This suite of CORT effects on vocal behavior are known to decrease attractiveness to females and were not related to a decrease in androgen level or differences in body condition in CORT- versus saline-injected males. 4. Our results suggest that CORT production during intraspecific vocal contests compromises male attractiveness. Male vocalizations may therefore reliably indicate recent contest outcomes and/or the stress status of males, implicating CORT as a mediator of honest signaling. We propose that the effects of agonistic acoustic signals on CORT production in this species are maintained by CORT-mediated life history trade-offs; decreased conspicuous signaling in high stress-responsive males potentially increases survival by reducing the likelihood of escalated contests with dominant males and detection by predators. Adoption of alternative non-calling satellite mating tactics may contribute to maintaining individual variation in stress responsiveness by increasing the chances that competitively inferior males acquire mates.1. 循环中应激激素（glucocorticoids，糖皮质激素）的短期升高通常会介导繁殖行为投入的减少，转而偏向于自我维持与生存，但这类效应在性选择与通讯中的意义仍未得到充分探究。 2. 本研究针对绿树蛙（Hyla cinerea），在同性选择与异性选择的背景下探究其急性应激反应。该物种的雄性个体能够产生争斗声学信号，该信号可刺激对手雄性体内应激激素皮质酮（CORT）的升高，这提示皮质酮在雄性间竞争中发挥核心作用。我们提出假说：鸣叫竞赛失败者体内升高的皮质酮水平，会介导分配至自我维持与生存的能量增加，进而削弱求偶信号展示的投入，最终降低对雌性的吸引力。 3. 与该假说一致，本研究结果显示：对正在鸣叫的雄性个体施加皮质酮给药处理，模拟鸣叫竞赛失败者体内的皮质酮分泌水平，会快速缩短其求偶鸣叫的时长并降低鸣唱投入。升高的皮质酮水平还会提升雄性在模拟领地入侵场景下产生攻击鸣叫的倾向，随后会增加其采取不鸣叫"卫星"交配策略的概率。已知皮质酮的这一系列鸣唱行为效应会降低对雌性的吸引力，且该效应与注射皮质酮组与注射生理盐水组雄性的雄激素水平下降或身体状况差异均无关联。 4. 本研究结果表明，种内鸣叫竞赛过程中产生的皮质酮会削弱雄性的吸引力。因此，雄性的鸣叫声可以可靠地反映其近期的竞赛结果和/或自身的应激状态，这提示皮质酮是诚实信号传递的介导因子。我们提出，该物种的争斗声学信号对皮质酮产生的效应，是通过皮质酮介导的生活史权衡（life history trade-offs）得以维持的：高应激响应性雄性的显眼信号展示减少，可通过降低与优势雄性发生升级争斗的概率以及被捕食者发现的概率，从而提升生存几率。采取替代性的不鸣叫卫星交配策略，可通过提升竞争力较弱的雄性获得交配机会的概率，有助于维持应激响应性的个体差异。