Spatiotemporal variation in the impacts of biological invasions

在世界范围内，在水生生态系统中发现非土著物种的速度越来越快。其中许多入侵似乎对生态造成了轻微的影响，而另一些入侵则对生物多样性和食物网造成了重大变化。我们预测哪些入侵将产生不良后果的能力受到上下文依赖性的阻碍：在当地环境条件的影响下，入侵者的影响在空间和时间上有所不同。我的研究计划的长期目标是开发模型来解释和预测生物入侵的影响。这一建议的目的是通过测试解释影响的时空变化的假设来探索上下文依赖性。三个主要假说是本提案的重点：1)入侵前沿假说预测，较新的入侵者，如那些在种群扩散的前部的入侵者，将产生与更高的摄食率和更高的攻击性相关的更高的影响，而来自更长的核心种群的个体将不那么贪婪和攻击性；2)环境匹配假说预测，入侵者将在接近其生理最适的非生物环境中产生更强的人均影响；以及3)资源消耗假说预测，最具破坏性的入侵物种比那些没有广泛入侵或影响历史的物种具有更高和更有效的资源消耗率。 我将使用在各种淡水和海洋栖息地对鱼类和甲壳类动物进行的实验室和野外实验相结合的方式作为模型系统。将为入侵捕食者提供猎物丰度增加的治疗，所消耗的猎物数量将与经典功能反应实验中提供的猎物相关，这将使我们能够量化人均影响。将通过比较温度、水化学和水流速度梯度的人均影响来纳入上下文依赖性。这些实验室实验将得到野外中胚层实验的补充，这些实验涉及入侵前沿和入侵者根深蒂固的核心地点之间的相互移植。实地选址将纳入自然环境梯度。 在测试这些假设时，我的实验室将识别和开发一些有价值的模型系统，这些系统可以用来为入侵理论提供信息，我们还将演示如何将环境背景纳入风险评估。

Nonindigenous species are being discovered in aquatic ecosystems at increasing rates worldwide. Many of these invasions appear to have minor ecological effects, while others cause substantial changes to biodiversity and food webs. Our capacity to predict which invasion will have undesirable consequences is impeded by context dependence: invader impacts vary across space and time under the influence of local environmental conditions. The long-term goal of my research program is to develop models that explain and predict the impacts of biological invasions. The aim of this proposal is to explore context dependency by testing hypotheses that explain spatiotemporal variation in impact. Three major hypotheses are the focus of this proposal: 1) the Invasion Front Hypothesis predicts that more recent invaders such as those at the front of a spreading population will exert higher impacts associated with higher feeding rates and heightened aggression, whereas individuals from longer established core populations will be less voracious and aggressive; 2) the Environmental Matching Hypothesis predicts that an invader will produce stronger per capita effects in an abiotic environment that closely matches its physiological optimum; and 3) the Resource Consumption Hypothesis predicts that the most disruptive invasive species have higher and more efficient resource consumption rates than those species without extensive invasion or impact histories. I will use a combination of lab and field experiments on fishes and crustaceans in a variety of freshwater and marine habitats as model systems. Treatments with increasing prey abundances will be offered to invasive predators, and the number of prey consumed will be related to prey supplied in a classical functional response experiment that will allow us to quantify per capita effects. Context dependency will be incorporated by comparing per capita effects across gradients of temperature, water chemistry and water velocity. These lab experiments will be complemented by field mesocosm experiments involving reciprocal transplants between the invasion front and core sites where the invader is well established. Field sites will incorporate natural environmental gradients. In testing these hypotheses, my lab will identify and develop some valuable model systems that can be used to inform invasion theory, and we will demonstrate how environmental context can be incorporated into risk assessment.