Ecological and Evolutionary Impacts of Pesticides on Non-target Organisms: A Focus on Amphibians

该项目侧重于生态环境在确定农药对自然界非目标生物的影响方面所起的作用。这项提案的总体目标是确定长期接触杀虫剂对两栖动物的生态和进化影响，两栖动物是全球保护关注的群体。本研究的第一个目的是检验暴露时间对农药暴露的致死率的影响。为了这个初步目标，八种两栖动物的幼虫将在不同的时间内受到一种常见的杀虫剂西维因的影响。本研究的第二个目的是确定生物和非生物生态环境如何与农药暴露相互作用以影响适应度性状。实验室研究表明，pH值的变化和捕食者线索的存在会使杀虫剂更加致命，但尚不清楚这些戏剧性的影响是否发生在自然条件下。此外，毒理学的重点一直集中在致命效应上，而对非致命效应（如个体特征的变化）的关注较少。然而，我们从生态学研究中知道，性状变化会对个体与其他物种的相互作用产生巨大影响。为了实现第二个目标，研究者将在池塘中饲养两栖动物幼虫，并研究农药、pH值和捕食者线索对个体生存和个体特征的相互作用影响。预计生态条件的自然差异将对农药致害性状和农药致害死亡率产生实质性影响。本研究的第三个目的是研究两栖动物对农药抗性的进化。关于许多害虫物种的进化抗性有大量的文献，但对非目标物种的进化抗性的调查明显缺乏，对两栖动物进化抗性的研究似乎不存在。为了研究两栖动物的抗性进化过程，研究者将采取三管齐下的方法，研究不同历史农药暴露的种群之间的抗性差异，农药抗性的遗传性，以及多代选择实验，以确定暴露于农药的两栖动物是否最终能够进化出对农药的抗性。预计在自然种群中存在农药抗性的遗传变异，暴露于农药将有利于两栖动物抗性的进化。总的来说，这项研究有望表明，生态环境对于理解农药对非目标生物的生态和进化影响至关重要。

This project focuses on the role that ecological context plays in determining the impact of pesticides on non-target organisms in nature. The overall goal of this proposal is to determine the ecological and evolutionary effects of long-term exposure to a pesticide on amphibians, a group of global conservation concern. The first objective of the research is to examine effects of exposure time on lethality of pesticide exposure. For this preliminary objective, eight species of larval amphibians will be subjected to carbaryl, a common pesticide, for varying lengths of time. The second objective of this study is to determine how the biotic and abiotic ecological environment interacts with pesticide exposure to affect fitness traits. Laboratory studies suggest that changes in pH and the presence of predator cues can make pesticides much more deadly, but it is unknown if these dramatic effects occur under natural conditions. Additionally, the toxicological focus has been on lethal effects with less of a focus on nonlethal effects such as changes in individual traits. However, we know from ecological studies that trait changes can have dramatic effects on how an individual interacts with other species. To achieve the second objective, the investigator will rear larval amphibians in pond mesocosms and examine the interacting impacts of pesticides, pH, and predator cues on individual survival and individual traits. It is predicted that the inclusion of natural differences in ecological conditions will have a substantial impact on the pesticide-induced traits and pesticide-caused mortality. The third objective of this study is to examine the evolution of pesticide resistance in amphibians. There is a vast literature on evolved resistance in many pest species, but investigations of evolved resistance in non-target species are noticeably lacking and studies of evolved resistance in amphibians appear to be nonexistent. To investigate the process of evolved resistance in amphibians, the investigator will take a three-pronged approach that examines differences in resistance among populations that differ in historical pesticide exposure, the heritability of pesticide resistance, and a multi-generation selection experiment to determine if amphibians exposed to pesticides can eventually evolve resistance to pesticides. The expectation is that there is genetic variation in pesticide resistance in natural populations and exposure to pesticides will favor the evolution of resistance in amphibians. Collectively, this research is expected to show that ecological context is critical for understanding the ecological and evolutionary impacts of pesticides in non-target organisms.