Niche theory predicts specialists will be more sensitive to
environmental perturbation compared to generalists, a hypothesis
receiving broad support in free-living species. Based on their niche
breadth, parasites can also be classified as specialists and
generalists, with specialists infecting only a few and generalists a
diverse array of host species. Here, using avian haemosporidian
parasites infecting wild bird populations inhabiting the Western Ghats,
India as a model system, we elucidate how climate, habitat and human
disturbance affects parasite prevalence both directly and indirectly via
their effects on host diversity. Our data demonstrates that
anthropogenic disturbance acts to reduce the prevalence of specialist
parasite lineages, while increasing that of generalist lineages. Thus,
as in free-living species, disturbance favors parasite communities
dominated by generalist vs. specialist species. Because generalist
parasites are more likely to cause emerging infectious diseases, such
biotic homogenization of parasite communities could increase disease
emergence risk in the Anthropocene