Global biogeography of bat-associated viruses

Bats (Chiroptera) are one of the most species-rich orders of mammals and harbour a highly diverse virome. Some bat-associated viruses have spilled over to humans, livestock, and other mammals, causing zoonotic diseases. However, a comprehensive overview on the diversity and biogeography of bat-associated viruses is missing, but highly relevant for Planetary Health. Here, we provide a biogeographic overview of global hotspots and biogeographic patterns of bat-associated virus richness in relation to biomes and continents. Publicly available data on bat-associated viruses was combined with data on global bat distribution to identify hotspots and biogeographic patterns of bat-associated virus richness. These patterns were linked to biomes and continents to detect underlying drivers.  In general, bat-associated virus richness increases from the poles to the equator, following bat species α-diversity. Southeast Asia, tropical Africa and Central America form distinct hotspots of bat-associated virus richness. Biogeographic patterns for virus families differed. Rhabdoviridae and Herpesviridae display high richness in the Americas and Coronaviridae richness is highest in Southeast Asia as well as tropical Africa. Moreover, bat-associated Astroviridae richness is highest in Southeast Asia, Paramyxoviridae richness is highest in tropical Africa, and Adenoviridae richness is highest in tropical Africa and Europe. However, biomes and continents as potential underlying drivers only explain a low amount of the observed variance. The here identified hotspots of bat-associated virus richness may harbour potentially zoonotic viruses. However, these hotspots need to be considered with caution due to biases and knowledge gaps. Only 353 out of the 1,449 currently accepted bat species have been associated to viruses. The knowledge gaps on bat-associated viruses are particularly high in tropical regions, which are known hotspots of bat diversity. Therefore, future research efforts – especially in tropical regions – are needed to sharpen our understanding of the bat virome and to identify potential areas at risk for future spillover events. 

Global richness of bat-associated viruses based on current knowledge. Overall, the richness increases from the poles to the equator. However, this pattern may be modified by climatic conditions such as continentality and precipitation regimens, as well as diversity and distribution of bat host species. Regions with the highest richness of known bat-associated viruses are located in Central America, tropical Africa, Southern Europe, and Southeast Asia. Note that deviations from this pattern may result from missing information or incomplete surveys (e.g., New Guinea, Madagascar, India, Amazon basin) whereas Northern America and Europe may be intensely studied.