Community Relationships of Malaria Parasites and Their Avian Hosts

人类经济的日益全球化、自然栖息地的持续碎片化以及气候的广泛变化为新疾病的出现创造了条件。作为第一步，评估病原体在宿主之间转换的可能性需要了解自然界中疾病有机体的多样性、分布和进化史。物种形成和宿主转换机制是出现新的疾病威胁的基础。该项目使用禽类疟疾病原体(疟原虫和血蛋白)作为研究寄生虫与其宿主之间进化和生态关系的模型系统。虽然疟疾在鸟类中很常见，但令人惊讶的是，人们对这些病原体在自然界中的种类和分布知之甚少。当宿主具有感染性时，可以很容易地在血液样本中检测到这种疾病。由于疟疾是一种毁灭性的人类疾病，人们对疟疾寄生虫进行了深入的研究，使应用分子技术识别感染和DNA测序确定进化谱系成为可能。这项技术将用于西半球22个地区的样本，包括西印度群岛，以评估寄主物种丰富度和地方性、扩散障碍和岛屿大小对寄生虫谱系数量的影响。该项目中获得的数据还将用于阐明禽类疟疾寄生虫的物种形成、种群灭绝和谱系灭绝的模式。禽类疟疾寄生虫的历史和地理反映了过去的传播和宿主转换，这将为了解疾病出现的一般过程提供洞察。

Increased globalization of the human economy, continued fragmentation of natural habitats, and widespread change in climate create conditions for the emergence of new diseases. Evaluating the potential for pathogens to switch between hosts requires, as a first step, an understanding of the diversity, distribution, and evolutionary history of disease organisms in nature. Mechanisms of species formation and host switching are basic to the emergence of new disease threats. This project uses avian malaria pathogens (Plasmodium and Haemoproteus) as a model system for studying evolutionary and ecological relationships between parasites and their hosts. Although malaria is common in birds, surprisingly little is known about the variety and distribution of these pathogens in nature. The disease can be detected readily in a blood sample when the host is infective. Because malaria is a devastating human disease, malaria parasites have been studied intensively, making possible the application of molecular techniques to recognize infections and DNA sequencing to identify evolutionary lineages. This technology will be used with samples from 22 localities in the Western Hemisphere, including the West Indies, to evaluate effects on the number of parasite lineages of host species richness and endemism, barriers to dispersal, and island size. The data obtained in this project also will be used to elucidate patterns of species formation, extirpation of populations, and extinction of lineages in avian malaria parasites. The history and geography of avian malaria parasites reflect spread and host switching in the past, which will provide insights into the general process of disease emergence.