Climate Warming’s Alteration of Host-Parasite Dynamics

Abstract

Parasites and pathogens have significant roles in host population control, and thus host-parasite interactions affect biodiversity. The important question reviewed in this paper is how changes in temperature due to climate change affect host-parasite interactions. There is mounting evidence that elevated temperatures have both beneficial and detrimental effects on parasites and independently on hosts. These independent changes result in altered host-parasite dynamics through various mechanisms. If elevated temperatures enhance parasite survival, risk of disease transmission among hosts is enhanced as well. This enhancement is dependent on temperature-induced shifts in the host lifecycle, as asynchrony in host and parasite development can result in decreased infection rate and disrupted disease transmission regardless of the increase in parasite survival and density. Host species differ in their responses to temperature elevation. Increased temperature can alter their susceptibility to parasites through changes in their immune functions. Climate shifts also result in host range shifts. As host ranges expand, they may encounter novel pathogens, increasing the risk of spillovers and resulting in a greater mortality rate. From the point of view of native species, newly arriving host species present the potential danger of introducing novel parasites and diseases, which can be detrimental to native species. For seasonally migratory species whose parasites typically decrease during their absence, any climate-induced increase in their parasites’ survival prior to their return may decrease the effectiveness of migration, shift their lifestyle to become more sedentary and thus reshape host-parasite dynamic. Altered balance of host-parasite interactions produces changes at higher ecological levels, and the efforts to conserve parasites should thus have the same priority as the need to conserve host species.