Daskin Joshua H, Alford Ross A
School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia.
Proc Biol Sci. 2012 Apr 22;279(1733):1457-65. doi: 10.1098/rspb.2011.2276. Epub 2012 Jan 11.
It is well known in ecology, evolution and medicine that both the nature (commensal, parasitic and mutualistic) and outcome (symbiont fitness, survival) of symbiotic interactions are often context-dependent. Less is known about the importance of context-dependence in symbioses involved in wildlife disease. We review variable symbioses, and use the amphibian disease chytridiomycosis to demonstrate how understanding context-dependence can improve the understanding and management of wildlife diseases. In chytridiomycosis, the host-pathogen interaction is context-dependent; it is strongly affected by environmental temperature. Skin bacteria can also modify the interaction; some bacteria reduce amphibians' susceptibility to chytridiomycosis. Augmentation of protective microbes is being considered as a possible management tool, but informed application of bioaugmentation requires understanding of how the interactions between host, beneficial bacteria and pathogen depend upon environmental context. The community-level response of the amphibian skin microbiota to environmental conditions may explain the relatively narrow range of environmental conditions in which past declines have occurred. Environmental context affects virulence and the protection provided by mutualists in other host-pathogen systems, including threatened bats and corals. Increased focus on context-dependence in interactions between wildlife and their symbionts is likely to be crucial to the future investigation and management of emerging diseases of wildlife.
在生态学、进化生物学和医学领域，共生相互作用的性质（共生、寄生和互利共生）及结果（共生体适应性、生存）通常取决于环境，这是广为人知的。然而，关于环境依赖性在野生动物疾病相关共生关系中的重要性，我们了解得较少。我们回顾了可变共生关系，并以两栖动物疾病壶菌病为例，说明理解环境依赖性如何能增进对野生动物疾病的认识与管理。在壶菌病中，宿主与病原体的相互作用取决于环境；它受到环境温度的强烈影响。皮肤细菌也能改变这种相互作用；一些细菌可降低两栖动物对壶菌病的易感性。增加保护性微生物被视为一种可能的管理手段，但明智地应用生物强化需要了解宿主、有益细菌和病原体之间的相互作用如何依赖于环境背景。两栖动物皮肤微生物群对环境条件的群落水平反应，可能解释了过去两栖动物数量下降所发生的相对狭窄的环境条件范围。环境背景会影响其他宿主 - 病原体系统（包括受威胁的蝙蝠和珊瑚）中的毒力和互利共生体提供的保护。更加关注野生动物与其共生体之间相互作用的环境依赖性，可能对未来野生动物新出现疾病的调查和管理至关重要。
