Acknowledgements
We thank Krista Raveala, Mikko Jalo, Pauliina Hyttinen, and Mikko Immonen for assisting in the field work, Laura Häkkinen for assisting in the laboratory work, and Elina Numminen for helping with the use of population database. We also thank Guillaume Blanchet for helpful discussions. This work was funded by the European Research Council (4100097 RESISTANCE) and Academy of Finland (334276) to A-LL, Academy of Finland (321441) to HS, and LUOVA doctoral program fellowship to SS.