IRCEB: Host-Pathogen Biology and the Global Decline of Amphibians

[9977063] collins等。我们建议在宿主-病原体生物学中建立一个具有强大解决问题重点的IRCEB，旨在加强合作并鼓励追求超越传统科学学科界限的答案。寄主-病原体相互作用交替地吸引和挫败生物学家。这种魅力源于这些系统提供了在基本层面上理解生物体关系背后复杂机制的模型。这种沮丧源于对这些相互作用的理解不够好，无法预测或应对流行病或动物流行病。生态学家越来越认识到病原体在种群动态和维持多样化群落和生态系统中的作用。然而，我们对病原体如何改变宿主种群动态，病原体如何感染种群中的宿主以及宿主和病原体种群如何共同进化知之甚少。在许多种群中，宿主和病原体共存，每一种种群规模都有规律地增加和减少。然而，有时病原体几乎或完全消灭其宿主种群。我们建议使用两栖动物作为模型系统来测试每种模式的基本机制。大多数两栖动物的种群在个体数量上有规律地波动，但大约从1989年开始，爬虫学家开始对种群甚至物种持续下降，有些濒临灭绝的报告感到震惊。极端的人口波动和下降集中在北美西部科迪勒拉山脉的广阔地区，从萨斯喀彻温南部到哥斯达黎加和巴拿马北部，以及澳大利亚从东南部到昆士兰北部的较高海拔地区。四个主要原因似乎单独、依次或协同作用：栖息地破坏、外来物种、疾病、有毒化学物质引起的人为环境变化、UB辐射或全球气候变化。许多下降的地区都是保护区，保护外来物种和栖息地免受破坏，这表明环境变化或病原体等微妙而复杂的原因在起作用。我们已经组建了一个国际研究小组来回答这个问题：为什么病原体会导致一些两栖动物数量下降，甚至灭绝？有证据表明，一种致病性壶菌导致两栖动物种群数量急剧下降，而另一种病原体虹膜病毒导致两栖动物种群数量波动。拟议的研究将解决以下问题：病原体如何影响宿主种群动态？是这些新引入的两栖动物病原体，还是历史上良性两栖动物的毒性发生了变化？最近的环境变化是否改变了两栖动物与病原体的相互作用？除了一些以人类为宿主的病例（如霍乱、疟疾）外，很少有从分子生物学到种群动力学的宿主-病原体相互作用的剖析。我们的团队将这样做，以推进基本的宿主-病原体生物学，目标是将我们的发现应用于当今我们面临的最重要的全球生物多样性问题之一：为什么两栖动物种群数量在下降？打个比方，日益减少的两栖动物问题就像一个反向的棱镜：它不是分散颜色，而是集中研究学科——生态学、进化论、有机体生物学、遗传学、病理学和免疫学——这样它们就不再是单独出现的。了解宿主-病原体相互作用的基本机制是我们的建议的核心，对于回答为什么两栖动物正在减少的问题至关重要。这个比喻的要点是，虽然光谱可以被“划分”成它的颜色，但变化是连续的——“划分”是人为的，在原点它们消失了。两栖动物是生态系统不可分割的一部分，因此它们处于这个隐喻的核心位置。因此，我们需要学科的多样性和愿意在综合研究项目上合作的研究者的多样性。两栖动物数量的减少是一个令人兴奋的，但不幸的是，探索宿主-病原体生物学边界的机会，现在是时候了解两栖动物数量减少的原因了。我们的IRCEB研究项目的重点是融合不同的学科概念、方法和传统，以促进我们对病原体作为两栖动物衰退因素的理解，这是生物多样性普遍丧失的一个关键例子。

9977063Collins et al. We propose an IRCEB in host-pathogen biology with a strong problem-solving focus designed to enhance collaboration and encourage pursuit of answers beyond the boundaries of traditional scientific disciplines. Host-pathogen interactions alternately fascinate and frustrate biologists. The fascination stems from the opportunities these systems offer as models for understanding at a basic level the complex mechanisms underlying organismal relationships. The frustration stems from not understanding these interactions sufficiently well to anticipate or react to epidemics or epizootics. Ecologists increasingly acknowledge a role for pathogens in population dynamics and in maintaining diverse communities and ecosystems. We have a poor understanding, however, of how pathogens alter host population dynamics, how pathogens infect hosts in a population, and how host and pathogen populations coevolve. In many populations, hosts and pathogens coexist and each shows regular increases and decreases in population size. At times, however, a pathogen nearly or completely decimates its host population. We propose testing the basic mechanisms underlying each of these patterns using amphibians as a model system. Most amphibian populations regularly fluctuate in numbers of individuals, but beginning about 1989 herpetologists became alarmed by reports that populations and even species were persistently declining, some to extinction. Extreme population fluctuations and declines are centered on a broad region of the Cordilleras of western North America from southern Saskatchewan south to Costa Rica and northern Panama, and the higher elevations of Australia from southeastern to north Queensland. Four main causes seem to be acting alone, sequentially, or synergistically: habitat destruction, exotic species, disease, and anthropogeneic environmental change due to toxic chemicals, UB radiation, or global climate change. Many regions with declines are conservation areas protected from exotic species and habitat destruction suggesting subtle, complex causes like environmental change or pathogens are at work. We have assembled an international research team to answer the question: Why are pathogens causing some amphibian populations to decline, even to extinction? The evidence suggests a pathogenic chytrid fungus causes populations to plummet, while another pathogen, an iridovirus causes amphibian populations to fluctuate. The proposed research will address the questions: How do pathogens influence host population dynamics? Are these newly-introduced amphibian pathogens, or has the virulence of historically benign amphibian associates changed? Have recent environmental changes altered amphibian-pathogen interactions? Except for some cases involving humans as hosts (e.g., cholera, malaria), few host-pathogen interactions have been dissected from molecular biology to population dynamics. Our team will do just that to advance basic host-pathogen biology with the goal of applying our findings to one of the most significant global biodiversity problems facing us today: Why are amphibian populations declining? Metaphorically, the declining amphibian problem is like a prism in reverse: instead of dispersing colors, it focuses research disciplines - ecology, evolution, organismal biology, genetics, pathology, and immunology - so that they no longer appear individually. Understanding the basic mechanisms of host-pathogen interactions is central to our proposal and essential for answering the question of why amphibians are declining. The point of this metaphor is that while a spectrum can be "divided" into its colors, the variation is continuous - "divisions" are artificial and at the origin they disappear. Amphibians are integral parts of ecosystems in ways that place them at this metaphorical core. Therefore, we need a diversity of disciplines and a diversity of investigators willing to collaborate on integrative research projects. The declining amphibian case in an exciting, but unfortunate, opportunity to explore the boundaries of host-pathogen biology, and the time is now to understand why amphibians are declining. The point of our IRCEB research program is to meld diverse disciplinary concepts, methods, and traditions in ways that advance our understanding of pathogens as a factor in amphibian declines, a key example of the general loss of biodiversity.