Anthropogenic disturbance favours generalist over specialist parasites in bird communities: Implications for risk of disease emergence

Abstract

Niche theory predicts specialists which 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 demonstrate 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 favours parasite communities dominated by generalist versus specialist species. Because generalist parasites are more likely to cause emerging infectious diseases, such biotic homogenisation of parasite communities could increase disease emergence risk in the Anthropocene.

How wild bees find a way in European cities: Pollen metabarcoding unravels multiple feeding strategies and their effects on distribution patterns in four wild bee species

“…Consequently, diet specialization and diet preference are two key traits determining the sensitivity to land‐use changes (e.g. urbanization; Dharmarajan et al., 2021) and the distribution patterns of wild bees (e.g. Fournier et al., 2020).…”

Effects of land use and climate change on functional and phylogenetic diversity of terrestrial vertebrates in a Himalayan biodiversity hotspot

“…Homogenization of the physical environment across the Himalayan landscape may be creating filters allowing only some lineages to persist thus increasing phylogenetic homogenization (decreasing MPD and MNTD in birds) (McKinney, 2006; Sol et al, 2017). This has implications for the health of community structure because closely related lineages are vulnerable to pathogens and diseases which, in turn, increases the risk of disease emergence in human populations (Dharmarajan et al, 2021).…”

An eco‐epidemiological modeling approach to investigate dilution effect in two different tick‐borne pathosystems

“…With regard to tick specialization, this has been observed to follow a pattern of global generalism and local specialism, which needs to be better investigated to better understand the circulation of tick-borne pathogens and exposure risks for humans and livestock (McCoy et al, 2013). Anthropogenic disturbance, and consequent habitat degradation, seems to favor generalist over specialist parasites (just like it has been observed in free living species; Dharmarajan et al, 2021), and this might be the case for vectors and particularly for ticks as well. However, if biotic homogenization of parasite communities usually leads to an increase in disease emergence risk, then pathosystems characterized by generalist ticks could be considered to be the keystone for the dilution effect hypothesis.…”