Acknowledgements:
I am grateful to Peter Eklöv, who supported all steps of this project. I further thank Leonie Haferkemper and Holger Villwock who have been an amazing help in the field and lab. Kasparas Bublys conducted the gut content analyses and Jenny Schulz created the map. Richard Svanbäck helped with discussions on individual specialization and Asbjørn Vøllestad gave insights to minnow population structure. Financial support came from the Knut and Alice Wallenberg foundation (grant KAW 2013.0091) and the Olsson Borghs stiftelse.