Department of Biology, Institute for Bird Behavior Studies, William & Mary, Williamsburg, VA, 23187, USA.
Institute for Integrative Conservation, William & Mary, Williamsburg, VA, 23187, USA.
Ecotoxicology. 2020 Oct;29(8):1138-1147. doi: 10.1007/s10646-020-02271-8. Epub 2020 Aug 30.
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.
为了检验性选择特征是否是环境毒物的特别敏感生物指示剂，我们评估了暴露于环境相关饮食浓度的污染物甲基汞对斑马雀（Taeniopygia guttata）的色素着色的影响。首先，我们测试了甲基汞对颜色的影响是否受暴露时间的影响。鸟类要么在发育过程中（孵化后最多 114 天）暴露，要么在成年后（达到性成熟后）暴露，要么终身暴露。与对照组相比，终身暴露于甲基汞的雄性鸟喙颜色较红，而以类胡萝卜素为基础的、有性选择特征的颜色则较浅。成年暴露对成年雄性鸟喙颜色没有影响，除了雏鸟的早期暴露可能有影响。对于雌性，鸟喙颜色不受强烈的性选择影响，终身或成年暴露于甲基汞都不会影响鸟喙颜色。对于雄性和雌性，终身或成年甲基汞暴露对背部羽毛的颜色都没有影响，背部羽毛是一种非性二态、基于黑色素的特征，不太可能是性选择的结果。这项研究是对性选择特征可能是环境毒素（如甲基汞）造成的应激的特别有用的生物指示剂的建议的全面实验检验。
