Climate refugia and migration requirements in complex landscapes

change events (Alley et al. 2003). Thus, the persistence of the species as a whole also does not imply that all local populations, subject to rapid regional climate changes, were able to survive. The capacity of species to migrate in response to past climate change have been inferred from where and when species appear in the palaeoecological record (Davis 1981, Huntley and Birks 1983, Delcourt and Delcourt 1987, King and Herstrom 1997, Gugger and Sugita 2010, Ordonez and Williams 2013a). However, such approaches are limited by a scarcity of fossil records and cryptic glacial refugia, which could result in overestimates of migration capability assessments (McLachlan et al. 2005, Snell and Cowling 2015). An alternative approach is to estimate past expansion rates based on species distribution models paired with reconstructions of palaeoclimates (Davis 1989, Davis and Zabinski 1992, Schwartz 1992, Iverson and Prasad 2002, Malcolm et al. 2002, Meier et al. 2012, Ordonez and Williams 2013a). Such models assume that all populations within a species range can occupy the entire realised niche of the species, but genetic adaptation to different environments within a species range do, in fact, impose additional constraints (Davis and Shaw 2001). For locally adapted populations to persist through environmental change, they must adapt, migrate, or face local extirpation (Aitken et al. 2008). In common and widespread Ecography 39: 1238–1246, 2016 doi: 10.1111/ecog.01998 © 2016 The Authors. Ecography © 2016 Nordic Society Oikos Subject Editor: John Williams. Editor-in-Chief: Nathan J. Sanders. Accepted 20 January 2016