Male mate choice in the Trinidadian guppy is influenced by the phenotype of audience sexual rivals

In populations with male mate-choice copying, males may mitigate their risk of sexual competition by reducing their preference for a particular female in the presence of sexual rivals (audience). Because of the cost of missed mating opportunities from such an audience effect, males should reduce their mating preference to a greater extent in the presence of more sexually competitive rivals compared with less competitive ones. We tested this hypothesis using the Trinidadian guppy (Poecilia reticulata). We compared a focal male’s baseline mating preference for either of 2 stimulus females, which differed in overall body size, in the absence of any sexual rival to his preference for the same females in the presence of a sexual rival using dichotomous-choice tests. Focal and audience males differed in body length and proportion of their body covered in orange and black pigmentation. In the presence of a larger rival, focal males exhibited a greater reduction in preference for their initiall...在存在雄性配偶选择拷贝（male mate-choice copying）现象的种群中，雄性可通过在性竞争者（即“观众”）在场时降低对特定雌性的偏好，以降低自身面临的性竞争风险。由于此类观众效应（audience effect）会带来错失交配机会的成本，相较于竞争力较弱的性竞争者，当面对竞争力更强的性竞争者时，雄性应更大程度地降低其交配偏好。我们以特立尼达孔雀鱼（Poecilia reticulata）为实验对象检验了这一假说。通过二项选择试验（dichotomous-choice tests），我们比较了焦点雄性（focal male）在无任何性竞争者时，对2只总体体型存在差异的刺激雌性（stimulus females）的基础交配偏好，与存在性竞争者时对同两只雌性的偏好差异。焦点雄性与观众雄性（audience males）在体长、身体橙色与黑色色素占比上存在差异。当面对体型更大的竞争者时，焦点雄性对其初始...