IRCEB: The Evolution of a Parasite and its Recently Colonized Host

1994年，一种新的鸣禽疾病出现在马里兰州后院的家雀身上。在这些禽类中观察到的严重的眼睛和呼吸系统疾病是由一种细菌引起的，这种细菌名为鸡毒支原体(MG)，显然是从家禽中跳出来的。自1994年以来，这种疾病已经在北美东部蔓延，估计有1亿只家雀死亡。本研究的重点是该寄生虫与其新定植宿主的共同进化。自1995/6流行年以来，东部雀形体病的发病率一直在稳步下降。这表明，要么是雀类进化出了对该病的遗传抗性，要么是MG进化出了降低毒力的遗传抗性，要么是抗性和毒力的某种组合发生了变化。将结合现场观察、控制感染实验和遗传分析来测试雀类对MG的进化遗传抵抗力，并测试MG毒力的变化。虽然这项研究的重点是一种不会感染人类的疾病，但从对脊椎动物种群和一种新病原体相互作用的研究中可以学到很多东西。我们生活在一个全球化的时代，新的病原体不断在家畜、野生动物和人类种群中传播。了解寄生虫和宿主之间相互作用的动态性质将为我们提供关键信息，帮助我们应对这些新的传染病。

0077804Hill, Roberts & EdwardsIn 1994, a new songbird disease appeared in House Finches in backyards in Maryland. The severe eye and respiratory disease that was observed in these birds was caused by a bacterium, Mycoplasma gallicepticum (MG), which had apparently "jumped" from poultry. Since 1994, this disease has spread throughout eastern North America, killing an estimated 100 million House Finches. This study focuses on the co-evolution of this parasite and its newly colonized host. There has been steady decline in the incidence of mycoplasmosis in eastern House Finches since the epidemic year of 1995/6. This suggests that either finches have evolved genetic resistance to the disease, that MG has evolved reduced virulence, or that some combination of change in resistance and virulence has occurred. A combination of field observations, controlled infection experiments, and genetic analysis will be used to test for evolved genetic resistance to MG in finches and to test for change in virulence in the MG. While this research focuses on a disease that does not infect humans, much can be learned from a study of the interaction of a vertebrate population and a novel pathogen. We live in an age of globalization with new pathogens constantly being spread among populations of domestic animals, wildlife, and humans. Understanding the dynamic nature of interactions between parasites and hosts will provide critical information to help us deal with these new infectious diseases.