Global amphibian decline: emerging infectious diseases and local extinctions

灭绝是任何物种的共同命运。然而，确定原因和过程往往是困难的。越来越多的证据表明，两栖动物实际上正面临着全球性的衰退，这为研究灭绝生物学提供了难得的机会。除其他原因外，新出现的传染病与这种下降有关。它们包括一种真菌感染，导致世界各地的物种灭绝，以及另一组两栖动物病原体，ranavirus，已被证明只导致局部死亡，但没有已知的灭绝。虽然这些病原体的生理机制已经被很好地理解，但宿主-病原体关系的生态和遗传成分仍有待研究。了解传染病生态学和进化是对灭绝进行更广泛调查的关键。因此，两栖动物是在野外研究这一过程的极好模型。它们不仅遭受这些新出现的传染病的折磨，而且在许多栖息地还面临着人为和生态的压力。只有在广泛的背景下探索这些疾病的作用，我们才能既测试病原体引起的灭绝，又找到适当的保护解决方案。为此，我将在安大略省北部建立一个长期项目，那里有受干扰和未受干扰的栖息地，最近也有疾病记录。通过实地观察和实验相结合，我将能够调查导致当地种群减少的病原体机制。考虑到目前关于群体遗传学和eid的知识和理论，本应用将测试的假设是：(1)宿主的易感性和死亡率差异具有显著的遗传成分(2)eid不仅在群体内造成大量死亡，而且影响个体发育和(3)环境因素影响疾病的广泛传播和感染的易感性。在全球两栖动物数量下降的背景下，该计划可以被视为连接生态学和遗传学的尝试，以创建一个可能被称为进化保护遗传学的领域。

Extinction is a common fate to any species. However, determining the causes and processes is often difficult. Increasing evidence suggests that amphibians are actually facing a global decline representing a singular opportunity to study the biology of extinction. Among other causes, emerging infectious diseases are involved in this decline. They consist of a fungal infection responsible in extinctions all around the world as well as another group of amphibian pathogens, ranaviruses, which have been shown to only cause local mortality but no known extinction. While the physiological mechanisms of these pathogens are well understood, the ecological and genetic components of the host-pathogen relationship remain to be studied. Understanding infectious disease ecology and evolution is a key to the more general investigation of extinction. Therefore amphibians are an excellent model for studying such a process in the wild. Not only do they suffer from these emerging infectious diseases but they also face anthropogenic and ecological pressure in many of their habitats. Only by exploring the role of these diseases in broad context will we be able to both test pathogen-induced extinctions and address appropriate conservation solutions. To this end, I will establish a long-term program in northern Ontario, where a matrix of disturbed and undisturbed habitats are present, and the diseases have been recently recorded. Using a combination of field observations and experiments, I will be able to investigate the pathogen mechanisms leading to the decline of local populations. Considering the current knowledge and theory on population genetics and EIDs, the hypotheses that will be tested in this application are (1) host differences in susceptibility and mortality have a significant genetic component (2) EIDs are not only causing mass mortalities within populations, but also affect individual development and (3) environmental factors affect the extensive spread of the diseases and the susceptibility of infection. In the context of the global amphibian decline, the program can be viewed as an attempt to bridge ecology and genetics to create a field that might be termed as evolutionary conservation genetics.