Dissertation Research: Eco-Evolutionary Dynamics of the Dilution Effect

生物多样性的一个令人惊讶的效果可能是减少疾病的传播：在存在其他宿主物种的情况下，一个宿主物种的感染率可能会更低。这个？稀释效应？当物种足够相似，以至于它们争夺食物等资源时，通常会出现这种情况。因此，物种多样性的净影响取决于多样性是否更能减少感染，而不是减少资源的可获得性。这个项目将使用两种浮游动物的人工群落、它们都吃的藻类和一种比另一种更容易感染其中一种浮游动物的真菌来研究稀释效应。以前对这些群落的研究表明，不太敏感的浮游动物对更容易受到影响的浮游动物的净影响取决于基因多样性：更容易受到影响的浮游动物的基因多样性越高，越有利于不太容易受到影响的浮游动物的存在。这表明，敏感浮游动物的快速进化是稀释效应发挥作用的必要条件。研究人员现在将测量敏感浮游动物的基因构成如何随着竞争和感染的进行而变化，以及基因变化如何导致浮游动物特征的变化以产生稀释效应。结果应该会增加对生态和进化如何相互影响以及生物多样性如何抗击疾病的理解。这项研究的更广泛影响包括应用于控制野生动物和人类的疾病。稀释效应在莱姆病、西尼罗河病毒、汉坦病毒和血吸虫病等严重疾病中可能很重要。该项目还将为本科生研究人员提供研究经验，包括代表人数不足的群体的成员。

One surprising effect of biological diversity can be to reduce the spread of disease: infection of one host species may be lower in the presence of other host species. This ?dilution effect? is typically seen when the species are similar enough that they compete for resources such as food. The net effect of species diversity then depends on whether diversity reduces infection more than it decreases the availability of resources. This project will investigate the dilution effect using artificial communities of two zooplankton, algae they both eat, and a fungus that infects one of the zooplankton more readily than the other. Previous work with these communities showed that the net effect of the less susceptible zooplankton on the more susceptible one depended on genetic diversity: the higher the genetic diversity of the more susceptible zooplankton, the more beneficial the presence of the less susceptible one. This suggests that rapid evolution of the susceptible zooplankton was required for the dilution effect to operate. Research will now measure how the genetic makeup of the susceptible zooplankton changes as competition and infection proceed, and how the genetic changes result in changes in the traits of the zooplankton to create a dilution effect. Results should increase understanding both of how ecology and evolution can affect each other and how biodiversity can counter disease. The broader impacts of this research include applications to control of disease in wildlife and in humans. Dilution effects may be important in serious diseases such as Lyme disease, West Nile virus, Hantavirus, and schistosomiasis. The project will also provide research experience for undergraduate researchers including members of underrepresented groups.