Global patterns in coronavirus diversity

Anthony, Simon J.; Johnson, Christine K.; Greig, Denise J.; Kramer, Sarah; Che, Xiaoyu; Wells, Heather; Hicks, Allison L.; Joly, Damien O.; Wolfe, Nathan D.; Daszak, Peter; Karesh, William; Lipkin, W. I.; Morse, Stephen S.; Mazet, Jonna A. K.; Goldstein, Tracey

Regional variation was also observed in the proportion of host switching events, relative to other evolutionary mechanisms such as co-speciation, duplication, or sharing (see Methods for definitions). Overall, host switching was the dominant mechanism, supporting the general trend observed for CoVs (Vijaykrishna et al. 2007; Woo et al. 2009; Lau et al. 2012 ) as well as similar findings for other viral families, including paramxyoviruses (Melade et al. 2016) , hantaviruses (Ramsden et al. 2009), and arenaviruses (Coulibaly-N'Golo et al. 2011; Irwin et al. 2012) . However, when analyzed by region, there were proportionally fewer events in Latin America compared with Africa or Asia. Given that host switching is the first critical step in zoonotic emergence (Li et al. 2005; Pfefferle et al. 2009; Woo et al. 2012; Azhar et al. 2014) , we suggest this finding could reflect regional differences in the risk of disease emergence.