Interpopulation variation and temperature mediation of the impacts of biological invasions

生态学家在了解外来物种如何入侵生态系统方面取得了实质性进展，但在预测这些物种何时何地会产生重大影响方面却不太成功。预测的一个主要挑战是环境依赖性，在这种情况下，一个非本地物种在不同的生态系统和不同的时间会产生相当不同的影响。我工作的长期目标是：1)确定驱动非本地物种影响时空变化的环境因素，2)将这些因素整合到一般预测模型中。在接下来的五年里，我将研究非本地淡水动物捕食率时空变化的原因。我的实验室将进行实验来验证三个主要假设。第一个假设预测，在种群扩张的前沿个体对食物网的影响更大，因为这些个体被选择为比那些来自高密度核心种群的个体更贪婪、更有竞争力。在入侵前线，动物的行为和体型的差异已经被认识了好几年，我们的实验室已经发现了证据，表明在入侵前线，捕食被放大了。我们将在之前工作的基础上，测试入侵时间对水生入侵物种种群内部和种群之间个体的功能反应（摄食效率）的影响。其次，在这些实验中，我们将操纵环境温度来验证这样一个假设，即变暖增强了入侵捕食者的功能反应，从而增加了猎物数量下降的可能性。第三，我们将通过比较分布在大湖区的鱼类和甲壳类非本土种群的功能响应来研究纬度格局。劳伦斯河流域。我们假设来自高纬度种群的个体比来自低纬度种群的个体具有更强的功能反应（由于更快的生长速度）。总的来说，这项研究将通过确定入侵者在空间和时间上影响变化的环境驱动因素，为理论和风险评估提供信息。特别是，它应该揭示非本地物种对水生生态系统的影响如何受到气候变化的影响的预测信息。

Ecologists have made substantial progress in understanding how nonnative species invade ecosystems, but have been less successful at predicting when and where such species will have significant impacts. A major challenge for prediction is context dependence, in which a nonnative species can have considerably different effects in different ecosystems and at different times. The long-term goals of my work are to i) identify environmental factors that drive spatiotemporal variation in the impact of nonnative species, and ii) integrate these factors into general predictive models. Over the next five years, I will investigate the causes of spatiotemporal variation in rates of prey consumption by nonnative freshwater animals. My lab will conduct experiments to test three overarching hypotheses. The first hypothesis predicts that individuals at the front of a spreading population exert greater impacts on food webs because such individuals are selected to be more voracious and competitive than those from the high-density core of the population. Differences in animal behavior and body size at invasion fronts have been recognized for several years, and our lab has found evidence that predation is amplified at invasion fronts. We will build on our previous work by testing the effect of time-since-invasion on the functional response (feeding efficiency) of individuals within and between populations of aquatic invasive species. Second, in these experiments we will manipulate ambient temperature to test the hypothesis that warming enhances an invasive predator's functional response such that it increases the likelihood of prey population decline. Third, we will investigate latitudinal patterns by comparing functional responses of nonnative populations of fish and crustaceans distributed across the Great Lakes-St. Lawrence River basin. We hypothesize that individuals from higher-latitude populations have stronger functional responses (owing to more rapid growth rates) than those from lower-latitude populations. Overall, this research will inform theory and aid risk assessment by identifying environmental drivers of variation in an invader's impacts across space and time. In particular, it should reveal predictive information on how the impacts of nonnative species in aquatic ecosystems are affected by climate change.