Global ecosystems are currently exposed to unprecedented environmental change. Although global change is often associated with range contractions or even extinctions (Thomas et al. 2004), some species emerge as profiteers and expand their range into newly emerging habitat (Le Roux and McGeoch 2008). Such expansions are usually interpreted as responses to changing environmental conditions at the range edge (Hickling et al. 2006). Moreover, they could simply be the result of phenotypic plasticity allowing species to exploit changing environmental conditions (Gienapp et al. 2008; Merilä and Hendry 2014) or could even be affected by bacterial infections (Goodacre et al. 2009). However, the potential for a successful expansion is not necessary inherent to a species, but could also be acquired by evolutionary adaptation (Parmesan 2006; Hill et al. 2011). While environmental change could initially trigger range expansions, only the interplay with adaptation to, for example, novel climatic conditions at the range edge may lead to massive expansions as currently observed for many species (Clements and Ditommaso 2011; Franks and Hoffmann 2012). An expanding population might initially be released from selection pressure by competitors, parasites, and predators. This release has been shown in many invasive species and might speed up the population's regrowth and facilitate an adaptation to novel environmental conditions in a new habitat (Keane and Crawley 2002; Menéndez et al. 2008; Phillips et al. 2010). After the evolution of novel phenotypes, for example, increased physiological tolerance, a population can further expand its range, much farther than by environmental change alone (Clements and Ditommaso 2011; Franks and Hoffmann 2012). Indeed, several examples of rapid adaptive divergence during contemporary range expansions and biological invasions have been observed (Huey et al. 2000; Phillips et al. 2006; Colautti and Barrett 2013; Krehenwinkel et al. 2015). Even in the face of considerable ongoing gene flow between expanding and native populations, strong selection can mediate adaptations (Saint‐Laurent et al. 2003). Gene flow and secondary contact might even provide expanding populations with novel variation and facilitate adaptive differentiation (Rius and Darling 2014). In fact, genetic signatures of isolation of populations by environmental conditions appear to be quite frequent and often override simple isolation by distance (Sexton et al. 2014). This suggests an important role of ecological divergence during contemporary range expansions. However, the interplay of different environmental factors, phenotypic plasticity, gene flow, selection, and adaptation remains poorly understood, especially in the initial stages of contemporary range expansions.