Linking Host Diversity and Amphibian Disease: Experimental and Field Studies

宿主-寄生虫的相互作用嵌入到动态的、通常是高度干扰的环境中，这可能会急剧改变宿主之间的感染模式和疾病风险。土地利用的变化以及由此引起的生物群落的变化与具有医学和兽医重要性的病原体的出现有关。然而，导致感染增加的生态机制通常仍然是推测的。这项提案研究了湿地周围正在进行的景观变化如何影响到一个新出现的具有保护重要性的问题：两栖动物肢体畸形。扁虫寄生虫Ribeiroia ondatrae依次感染淡水蜗牛、幼虫两栖动物和鸟类，已被认为与两栖动物普遍存在的肢体畸形有关。感染和由此产生的畸形也增加了两栖动物的死亡率，有可能导致两栖动物数量的下降。目前的提案建立在之前资助的NSF研究和生态学理论的基础上，结合了广泛的实地调查和机械实验，以了解土地利用的变化，通过改变宿主密度和宿主多样性，将如何促进或限制Ribeiroia丰度和两栖动物畸形。这项工作将具体寻求查明淡水生态系统中生物多样性的丧失如何影响病原性寄生虫的传播，如里贝罗伊氏菌。考虑到威胁人类健康和野生动物保护的新出现感染的数量不断增加，拟议的努力成果具有广泛的应用潜力。Ribeiroia不仅自身的保护重要性与日俱增，而且是其他具有经济和人类健康意义的寄生虫感染的极好类似物(例如人类血吸虫)。这项提议将进一步支持两栖生物学家和生态学家之间的合作努力，以解决世界各地两栖动物数量持续下降的问题。

Host-parasite interactions are embedded within dynamic, often highly disturbed environments, which can sharply alter patterns of infection and disease risk among hosts. Changes in land use and the resulting shifts in biological communities have been linked to the emergence of pathogens with medical and veterinary importance. However, the ecological mechanisms responsible for increases in infection often remain conjectural. This proposal examines how the ongoing transformation of landscapes surrounding wetlands influences an emerging issue of conservation importance: amphibian limb deformities. The flatworm parasite Ribeiroia ondatrae, which sequentially infects freshwater snails, larval amphibians, and birds, has been linked to widespread limb deformities in amphibians. Infection and the resulting malformations also increase amphibian mortality, potentially causing declines in amphibian populations. Building upon previously funded NSF research and ecological theory, the current proposal combines broad-scale field surveys and mechanistic experiments to understand how land use change, by altering host density and host diversity, will promote or limit Ribeiroia abundance and amphibian malformations. This effort will specifically seek to identify how biodiversity losses in freshwater ecosystems affect the transmission of pathogenic parasites, such as Ribeiroia. Considering the growing number of emerging infections that threaten human health and wildlife conservation, results of the proposed efforts have broad application potential. Ribeiroia is not only growing in conservation importance itself, but is an excellent analog for other parasite infections of economic and human-health significance (e.g., human blood flukes). This proposal would further support cooperative efforts among amphibian biologists and ecologists to address ongoing declines in amphibian populations worldwide.