Data from: Environmental conditions limit attractiveness of a complex sexual signal in the túngara frog

Animals choosing particular display sites often balance sexual and natural selection pressures. Here we assess how physical properties of display sites can alter this balance by influencing signal production and attractiveness of the túngara frog (Physalaemus pustulosus). Males that call from very shallow water bodies (few mm depth) benefit from reduced predation risk, but by manipulating water levels, we show that this comes at a cost of reduced attractiveness to females. Our data show that calling from shallower water reduces a male's ability to float, limits the inflation of his vocal sac, and consequently reduces signal conspicuousness in terms of amplitude and complexity. Our results demonstrate that display site properties can set limits on signal production and attractiveness and may hence influence signal evolution. Signallers may shift between sites or engineer their display location, which can play a crucial role in signal divergence and speciation, particularly in a rapidly changing world.

选择特定展示位点的动物，通常需要在性选择与自然选择的压力之间维持平衡。本研究以湍蛙（túngara frog, Physalaemus pustulosus）为对象，探究展示位点的物理属性如何通过影响信号产生与个体吸引力，进而改变这一平衡。栖息于极浅水域（水深仅数毫米）的雄性个体，捕食风险会有所降低，但我们通过调控水位的实验发现，此举会以降低对雌性的吸引力为代价。实验数据表明，在更浅的水域鸣叫会削弱雄性的漂浮能力，限制其声囊的充气扩张，进而降低信号在振幅与复杂度层面的显著性。本研究结果证实，展示位点的物理属性会对信号产生与个体吸引力构成限制，因此可能会影响信号的演化进程。信号发出者可在不同位点间切换，或是主动改造自身的展示位置，这一过程对信号分化与物种形成至关重要，在当前快速变化的全球环境中尤为如此。