“…The two streams in our experiment are separated by approximately 500 m but differ in temperature by 11°C. Dispersal, gene flow and genetic divergence among populations in this species are strongly related to geographic distance (Johansson, Quintela, & Laurila, 2016), and R. balthica are known to disperse slowly, but regularly over short distances (Hoffman et al, 2006;Kappes & Haase, 2012), but rarely over long distances, where such events are usually associated with passive dispersal, for example, via association with vertebrates (Bolotov et al, 2017;Hansson & Akesson, 2014). Thus, our study, over a relatively small spatial scale (500 m), provides insight into how metabolic and resource acquisition traits in closely related natural populations have diverged in response to warming and is therefore directly relevant for understanding the effects of rapid climate change (Keller, Alexander, Holderegger, & Edwards, 2013;Meril€ a & Hendry, 2014;Richter-Boix, Teplitsky, Rogell, & Laurila, 2010).…”