Community Relationships of Malaria Parasites and Their Avian Hosts

人类经济的日益全球化、自然栖息地的持续破碎化以及气候的广泛变化为新疾病的出现创造了条件。评估病原体在宿主之间转换的潜力需要，作为第一步，了解自然界中疾病生物的多样性，分布和进化历史。物种形成和宿主转换机制是新疾病威胁出现的基础。该项目使用禽疟疾病原体（疟原虫和血变形杆菌）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。当宿主具有传染性时，这种疾病很容易在血液样本中检测出来。由于疟疾是一种毁灭性的人类疾病，疟疾寄生虫已被深入研究，使分子技术的应用成为可能，以识别感染和DNA测序，以确定进化谱系。这项技术将用于从22个地点在西半球，包括西印度群岛的样本，以评估宿主物种丰富性和特有性，传播障碍，和岛屿大小的寄生虫谱系的数量的影响。本计画所获得的资料也将用来阐明鸟类疟疾寄生虫的物种形成、族群灭绝及谱系灭绝的模式。禽疟疾寄生虫的历史和地理反映了过去的传播和宿主转换，这将为疾病出现的一般过程提供见解。

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.