Although visual sexual signals, such as ornamental colors and courtship displays, and large body size in males are attractive to females in numerous species, they may also inadvertently attract the attention of eavesdropping predators and thus may be costly in terms of increasing individual risk of mortality to predation. Theoretically, more color ornamented and larger males should be more predation threat sensitive and suppress their sexual signaling and(or) mating effort relatively more than their less color ornamented and smaller counterparts when under predation hazard. Here, we experimentally tested this hypothesis by quantifying concurrently the rates of alternative mating tactics (courtship displays, sneak mating attempts) expressed by male Trinidadian guppies (Poecilia reticulata) varying in color ornamentation and body size under a staged immediate threat of predation. Males suppressed their overall mating effort in response to the perceived predation threat, decreasing the frequency of their (presumably more conspicuous) courtship displays significantly more on average than the frequency of their sneak mating behavior. Statistically controlling for body length, more color-ornamented males were more threat sensitive in their courtship displays, but not sneak mating attempts, under predation hazard than drabber males. Controlling for body coloration, larger males exhibited lower courtship and sneak mating efforts than smaller males in both predation treatments, but body length only influenced threat sensitivity in sneak mating behavior. These results are consistent with both the threat sensitive hypothesis and asset protection principle and highlight the phenotype dependency and adaptive plasticity of alternative mating tactics in male guppies under varying predation risk.

中文翻译：

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性吸引力特征预测雄性替代交配策略的捕食威胁敏感性

尽管视觉性信号，例如装饰性颜色和求爱展示，以及雄性的大体型对许多物种中的雌性具有吸引力，但它们也可能无意中引起偷听的捕食者的注意，因此在增加个体死亡风险方面可能代价高昂到掠食。从理论上讲，更多颜色装饰和更大的雄性应该对捕食威胁更加敏感，并且在面临捕食危险时，比更少颜色装饰和较小的同类更能抑制它们的性信号和（或）交配努力。在这里，我们通过同时量化雄性特立尼达孔雀鱼（Poecilia reticulata）在面临分阶段的直接捕食威胁时表现出的不同颜色装饰和体型的替代交配策略（求爱展示、偷偷交配尝试）的比率，通过实验检验了这一假设。雄性为了应对感知到的捕食威胁而抑制了整体交配努力，降低了它们（可能更明显的）求偶行为的频率，平均而言明显多于它们偷偷交配行为的频率。从统计数据上控制体长来看，更多颜色装饰的雄性在求偶表现中对威胁更敏感，但在捕食危险下，比单调的雄性对偷偷交配的尝试更敏感。在控制身体颜色的情况下，在两种捕食处理中，较大的雄性表现出比较小的雄性更低的求爱和偷偷交配努力，但体长只影响偷偷交配行为的威胁敏感性。这些结果与威胁敏感假说和资产保护原则一致，并强调了雄性孔雀鱼在不同捕食风险下的表型依赖性和替代交配策略的适应性可塑性。