Shaw Allison K, Binning Sandra A
Am Nat. 2016 Apr;187(4):491-501. doi: 10.1086/685386. Epub 2016 Feb 23.
Migration, a widespread animal behavior, can influence how individuals acquire and transmit pathogens. Past work has demonstrated that migration can reduce the costs of pathogen or parasite infection through two processes: migratory escape from infected areas or individuals and migratory culling of infected individuals. Here, we propose a third process: migratory recovery, where infected individuals lose their parasites and recover from infection during migration. Recovery can occur when parasites and/or their intermediate hosts cannot support changes in the migratory host's internal or external environment during migration. Thus, parasite mortality increases with migration. Although migratory recovery is likely widespread across species, it remains challenging to empirically test it as a selective force promoting migration. We develop a model and determine the conditions under which migratory recovery theoretically favors the evolution of migration. We show that incorporating migratory recovery into a model of migratory escape increases the range of biologically realistic conditions favoring migration and leads to scenarios where partial migration can evolve. Motivated by empirical estimates of infection costs, our model shows how recovery from infection could drive the evolution of migration. We suggest a number of future directions for both theoretical and empirical research in this area.
迁徙是一种广泛存在的动物行为，它会影响个体获取和传播病原体的方式。过去的研究表明，迁徙可以通过两个过程降低病原体或寄生虫感染的成本：从受感染区域或个体中迁徙逃离，以及对受感染个体进行迁徙淘汰。在此，我们提出第三个过程：迁徙恢复，即受感染个体在迁徙过程中摆脱寄生虫并从感染中恢复。当寄生虫和/或它们的中间宿主在迁徙过程中无法适应迁徙宿主内部或外部环境的变化时，恢复就可能发生。因此，寄生虫死亡率会随着迁徙而增加。尽管迁徙恢复可能在物种中广泛存在，但要通过实证检验它作为促进迁徙的一种选择力量仍具有挑战性。我们构建了一个模型，并确定了在哪些条件下，从理论上来说迁徙恢复有利于迁徙的进化。我们表明，将迁徙恢复纳入迁徙逃离模型中，会增加有利于迁徙的生物学现实条件的范围，并导致部分迁徙能够进化的情况。基于对感染成本的实证估计，我们的模型展示了从感染中恢复如何推动迁徙的进化。我们为此领域的理论和实证研究提出了一些未来的方向。
