Dissertation Research: The Role of Pathogens in the Maintenance of Host Genetic Variation

农业作物通常作为基因单一栽培作物种植，以容易生病而臭名昭著。相比之下，自然植物种群很少受到疾病的感染；它们通常也是遗传可变的。最近，生物学家假设，自然种群典型的遗传多样性可能是疾病有机体实施自然选择的产物，但很少有研究检验这一假设。研究人员将通过比较芥菜科亲缘关系密切的物种对锈病的抵抗力来研究疾病在维持宿主遗传多样性方面的作用。这些芥菜品种中的一些没有遗传变异，而另一些物种的遗传变异。为了使疾病能够促进遗传变异，疾病必须对宿主施加强有力的选择；也就是说，它必须减少宿主的存活和/或繁殖，并且必须遗传抗性。这项研究的目标是确定是否满足这些条件，以及确定基因一致的物种是否比遗传可变的物种对疾病的抵抗力更差，以及在有和没有这种疾病的地方自然植被的组成是否不同。

Agricultural crops, which are usually planted as genetic monocultures, are notoriously prone to disease. Natural plant populations, by contrast, are rarely as infected by disease; they are also typically genetically variable. Recently, biologists have postulated that the genetic diversity typical of natural populations may be a product of natural selection exerted by disease organisms, but few studies have tested this hypothesis. The investigators will examine the role of disease in maintaining host genetic variation by comparing resistance of closely related species in the mustard family to a rust disease. Some of these mustard species have no genetic variability, whereas other species are genetically variable. For disease to be capable of promoting genetic variation, the disease must exert strong selection on its hosts; that is, it must decrease survival and/or reproduction of the hosts, and resistance must be inherited. The goals of this study are to determine whether these conditions are met, as well as to determine whether the genetically uniform species are less resistant to disease than the genetically variable species, and whether the composition of natural vegetation is different in places with and without this disease.