Understanding the factors underlying host shifts is a major goal for infectious disease researchers. This effort has been further complicated by the fact that host-parasite interactions are now taking place in a period of unprecedented global climatic warming. We investigated how host shifts are affected by temperature by carrying out experimental infections using an RNA virus across a wide range of related species, at three different temperatures. We find that as temperature increases the most susceptible species become more susceptible, and the least susceptible less so. We found no significant relationship between a species’ susceptibility across temperatures and proxies for thermal optima; critical thermal maximum and minimum or basal metabolic rate. This has important consequences for our understanding of host shift events in a changing climate, and suggests that temperature changes may affect the likelihood of a host shift into certain species.
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