1. Department of Zoology, University of Oxford, Oxford, OX1 3PS, United Kingdom
2. Department of Environmental Sciences, Eidgenössiche Technische Hochschule Zürich, CH‐8092 Zürich, Switzerland
3. Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), CH‐8600 Dübendorf, Switzerland
4. E‐mail:
5. Centre for Immunity, Infection & Evolution, School of Biological Sciences, University of Edinburgh, United Kingdom
6. Biosciences, University of Exeter, Penryn, TR10 9EZ, United Kingdom