“…Populations in the H. leucophrys complex occurring at high elevations in the Sierra Nevada de Santa Marta (Caro et al, 2013) and the Andes of Ecuador (Dingle et al, 2008(Dingle et al, , 2010 Marta and the Andes, regional differences in factors other than, or in addition to temperature, have led to an absence of convergent evolution in feathers; or (3) populations from different regions may have responded to the challenges of high elevations in different ways (e.g., more insulative plumage vs. greater thermogenic capacity). Alternatively, we speculate that in mountains where a single species exists across a large elevational gradient, high gene flow along mountain slopes (as shown in Linck et al, 2020and Pujolar et al, 2022, but see Polato et al, 2018 may restrict the emergence of adaptive variation in the highlands owing to swamping of locally beneficial alleles by maladaptive variants arriving via dispersal from lower elevations (Bachmann et al, 2020;Bridle et al, 2009;Bridle & Vines, 2007;Polechová & Barton, 2015). In…”