Tolerance as a Parasite Defense in a Colonial Bird

所有生物都必须保护自己免受它们所接触的致病寄生虫和病原体的侵害。这种防御发生的典型方式是抵抗病原体或寄生虫，通常是通过免疫反应。宿主的抵抗力是许多现代医学的基础，其中免疫反应被各种疗法增强或取代。然而，另一种防御是寄生虫或病原体的耐受性，而不产生任何抗性，这（在某些情况下）可能对宿主有益，部分原因是耐受性不需要宿主产生免疫反应的生理成本。众所周知，植物能耐受各种病原体，但动物耐受寄生虫的能力直到最近才被认识到。这个项目记录了一种殖民地鸟类，悬崖燕子，如何快速进化（超过30年）忍受大量吸血寄生虫的能力。通过比较这些寄生虫在20世纪80年代对鸟类的影响与今天的影响，我们将深入了解在群居动物中，作为寄生虫防御的耐受性发展的条件。研究结果将对了解动物（包括人类）如何潜在地减少寄生虫的负面影响以及有时与这些寄生虫有关的疾病具有广泛的相关性。在植物-寄生虫系统中，寄生虫的耐受性是宿主防御的关键，但很少有实证研究探索耐受性在动物宿主-寄生虫关系中的作用。本研究旨在研究群巢崖燕（Petrochelidon pyrrhonota）及其主要寄生物燕子虫（半翅目：蠓科：蠓科：Oeciacus vicarius）对寄生虫的耐受防御策略的生态学和进化。这项工作建立在长期的实地研究和相对较近的岩燕选择新的筑巢地点的基础上，在那里它们与巢中的寄生虫接触更多。在20世纪80年代，昆虫对崖燕的繁殖成功产生了严重影响，但随后的观察表明，在这30年里，这种鸟可能已经进化出了更大的对寄生的耐受性。这项研究旨在确定崖燕现在是否能更好地忍受寄生虫，以及鸟类是如何忍受寄生虫的？因此，抗寄生虫的行为可能会发生变化。这项工作的新颖之处在于，它首次研究了自然种群中耐受性的时间变化。这项研究将涉及本科生和一名博士后科学家，一名社区学院教员的参与将促进城市少数民族学生的参与。因为增强宿主的耐受性在对抗炎症和自身免疫性疾病方面可能比开抗生素（一种促进对寄生虫的抵抗力的策略）更有效，这项研究将鼓励非科学家考虑将耐受性作为一种治疗选择。

All living organisms must defend themselves from disease-causing parasites and pathogens to which they are exposed. The typical way that such defense occurs is by resisting the pathogen or parasite, often through an immune response. Resistance by the host is the basis for much of modern medicine, in which the immune response is enhanced or replaced by various therapies. However, another defense is the tolerance of the parasite or pathogen without mounting any resistance, which (under certain circumstances) can be beneficial to the host, in part because tolerance does not require the host to incur the physiological cost of mounting an immune response. Plants are well known to tolerate various pathogens, but the ability of animals to tolerate parasites has only recently been recognized. This project documents how a colonial bird, the cliff swallow, has rapidly evolved (over 30 years) the ability to tolerate large numbers of blood-feeding parasitic bugs. By comparing the effects of these parasites on the birds in the 1980s versus their effects today, insight into conditions that favor the development of tolerance as a parasite defense in a social animal will be gained. The results will have wide relevance to understanding ways that animals (including humans) can potentially minimize the negative effects of parasites and the diseases sometimes associated with those parasites.Parasite tolerance has been established as a key host defense in plant-parasite systems, but few empirical studies have explored the role of tolerance in animal host-parasite relationships. This research seeks to study the ecology and evolution of tolerance defense strategies against parasites in colonially nesting cliff swallows (Petrochelidon pyrrhonota) and their principal parasite, the swallow bug (Hemiptera: Cimicidae: Oeciacus vicarius). The work builds on a long-term field study and the relatively recent adoption of new nesting sites by cliff swallows where they have come into greater contact with their nest parasites. During the 1980s, bugs exerted severe effects on cliff swallow reproductive success, but subsequent observation suggests that the birds may have evolved greater tolerance to parasitism in the intervening 30 years. This research seeks to establish whether cliff swallows now better tolerate parasites and how the birds? anti-parasite behavior may be changing as a result. The novelty of this work is that it is the first to examine temporal changes in tolerance within a natural population. This research will involve undergraduate students and a postdoctoral scientist, and participation by a community college faculty member will facilitate involvement of urban minority students. Because enhancing tolerance by the host may be more effective in fighting inflammatory and autoimmune diseases than prescribing antibiotics (a strategy that promotes resistance to parasites), this research will encourage non-scientists to think about tolerance as a treatment option.