Climate warming triggers the emergence of native viruses in Iberian amphibians

The number of epizootics in amphibian populations caused by viruses of the genus Ranavirus is increasing worldwide. Yet, causes for pathogen emergence are poorly understood. Here, we confirmed that the Common midwife toad virus (CMTV) and Frog virus 3 (FV3) are responsible for mass mortalities in Iberia since the late 1980s. Our results illustrate the Iberian Peninsula as a diversity hotspot for the highly virulent CMTV. Although this pattern of diversity in Europe is consistent with spread by natural dispersal, the exact origin of the emergence of CMTV remains uncertain. Nevertheless, our data allow hypothesizing that the Iberian Peninsula might harbor the ancestral population of CMTVs that could have spread into the rest of Europe. In addition, we found that climate warming could be triggering the CMTV outbreaks, supporting its endemic status in the Iberian Peninsula.
This work was supported by Organismo Autónomo Parques Nacionales of Spain (ref. 2399/2017; PI: JB), Foundation for the Conservation of Salamanders (project ‘‘Monitoring the incidence of emerging pathogens on endemic urodeles from the Cantabrian range, Spain’’; PI: BT), and Fundaçao para a Ciencia e a Tecnologia (Ref. PTDC/BIA-CBI/2434/2021; PI: GMR,Co-PI: JB).