School of Biological Sciences, Monash University, Victoria, Australia; Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden.
School of Biological Sciences, Monash University, Victoria, Australia.
Sci Total Environ. 2020 Feb 10;703:134991. doi: 10.1016/j.scitotenv.2019.134991. Epub 2019 Nov 2.
A leading source of endocrine-disrupting chemicals (EDCs) in the environment is run-off of veterinary pharmaceuticals used in agriculture, including hormonal growth promotants (HGPs). Despite being banned in various countries, HGP use is still common in beef production around the world. The androgenic steroid 17β-trenbolone (17β-TB) is a HGP that commonly enters surface waters via livestock effluent run-off. Here, we used a flow-through system to expose wild-caught adult male guppies (Poecilia reticulata) to an environmentally realistic level of 17β-TB (average measured concentration = 2 ng/L) for 21 days. We then compared the response of exposed and unexposed males to sequentially presented large and small stimulus (unexposed) females. Due to a positive size-fecundity relationship, larger females are generally expected to be preferred by males. While we found no evidence that the size of a previously encountered female affected the amount of courtship or coercive 'sneak' mating behaviour performed by males during the second presentation, males from both exposure treatments conducted more frequent courting events towards larger females during both presentations, suggesting an absolute preference for greater female size. Further, across both presentations, 17β-TB exposure caused a shift in male mating strategy towards increased coercive sneaking behaviour, although male sequential investment into mating effort was not impacted at the tested dosage. In combination, our findings demonstrate that exposure to a field-realistic level of a widespread agricultural pollutant alters male mating strategies in fish, and contribute to a growing understanding of sub-lethal impacts of chemical contaminants on complex behaviours in wildlife.
环境中内分泌干扰化学物质（EDCs）的一个主要来源是农业中使用的兽医药品的径流，包括激素生长促进剂（HGPs）。尽管在许多国家被禁止，但 HGP 在世界范围内的牛肉生产中仍然很常见。雄激素类固醇 17β-群勃龙（17β-TB）是一种 HGP，通常通过牲畜废水径流进入地表水。在这里，我们使用流动系统将野生捕获的成年雄性孔雀鱼（Poecilia reticulata）暴露于环境现实水平的 17β-TB（平均测量浓度为 2ng/L）中 21 天。然后，我们比较了暴露和未暴露的雄性对连续呈现的大、小刺激（未暴露）雌性的反应。由于大小与繁殖力呈正相关，通常较大的雌性更受雄性青睐。虽然我们没有发现先前遇到的雌性的大小会影响雄性在第二次出现时进行求偶或强制性“偷偷”交配行为的数量的证据，但来自两种暴露处理的雄性在两次出现期间对较大的雌性进行了更频繁的求偶行为，这表明它们对雌性的大小有绝对的偏好。此外，在两次出现期间，17β-TB 暴露导致雄性交配策略向增加强制性偷偷交配行为转变，尽管在测试剂量下，雄性对交配努力的连续投资没有受到影响。总的来说，我们的研究结果表明，暴露于环境现实水平的广泛农业污染物会改变鱼类的雄性交配策略，并有助于深入了解化学污染物对野生动物复杂行为的亚致死影响。
