To examine whether sexually selected traits are particularly sensitive bioindicators of environmental toxicants, we assessed the effects of exposure to environmentally relevant dietary concentrations of the pollutant methylmercury on pigment coloration in zebra finches (Taeniopygia guttata). First, we tested whether effects of methylmercury on coloration were influenced by timing of exposure. Birds were either exposed developmentally (up to 114 days after hatching), as adults (after reaching sexual maturity), or for their entire life. Bill coloration, which is a carotenoid-based, sexually selected trait, was less red in males with lifetime exposure to methylmercury, compared to controls. Neither adult, nor developmental exposure influenced bill color in adult males, with the possible exception of early exposure of nestlings. Among females, where bill color is not under strong sexual selection, neither lifetime nor adult exposure to methylmercury affected bill color. For males and females, there was no effect of either lifetime or adult methylmercury exposure on coloration of back feathers, which is a non-sexually-dimorphic, melanin-based trait that is not likely the result of sexual selection. This study is a comprehensive experimental test of the proposal that sexually selected traits may be particularly useful bioindicators of the stress imposed by environmental toxins such as methylmercury.

为了检查性选择的特征是否对环境毒物特别敏感，我们评估了与环境相关的饮食中污染物甲基汞的饮食接触对斑马雀（Taeniopygia guttata）色素着色的影响。）。首先，我们测试了甲基汞对着色的影响是否受暴露时间的影响。鸟类或者成年（达到性成熟后）处于发育期（孵化后长达114天）或一生中处于暴露状态。比尔色是一种基于类胡萝卜素的性选择特征，与对照组相比，一生中暴露于甲基汞的男性的红色较少。成年雄性和成年雄性都不受影响，除了雏鸟的早期暴发外，其他情况下的成色都不受影响。在钞票颜色不受强烈性别选择的女性中，一生或成年甲基汞暴露都不会影响钞票颜色。对于雄性和雌性，一生或成年甲基汞暴露对后羽毛的着色都没有影响，后者是非性双态的，基于黑色素的性状，可能不是性选择的结果。这项研究是对提议的一项综合性实验测试，该提议认为性选择的性状可能是环境毒素（例如甲基汞）施加的压力的特别有用的生物指标。