“…the independent colonization of high-altitude environments by multiple species) complement insights derived from controlled laboratory experiments. For example, comparative studies have documented that high-altitude rodents often have higher Hb and/or blood O 2 affinities than their lowland relatives (Hall et al, 1936;Bullard et al, 1966;Ostojic et al, 2002;Storz, 2007;Storz et al, 2009Storz et al, , 2010aNatarajan et al, 2013Natarajan et al, , 2015aJensen et al, 2016), and these observations complement the results of experiments demonstrating that increases in blood-O 2 affinity enhance tissue O 2 delivery and measures of physiological performance in rodents subjected to environmental hypoxia (Eaton et al, 1974;Turek et al, 1978a,b;Chappell and Snyder, 1984). Such consilience of evidence from comparative and experimental studies can greatly strengthen conclusions about the adaptive significance of evolutionary changes in Hb-O 2 affinity.…”