Fig. 5

a Topographic profiles of the two cordilleras separating sampling sites in the Vilcanota region and along the Manu Road (see Fig. 1c). Arrows with red lettering indicate mean migration rates (m) estimated from IMa2 analyses (Table 4). b Bill length differences among the four Cusco localities. Blue represents the two humid sites and brown the two drier sites. Asterisks indicate p-values for the comparisons of bill length between two pairs of adjacent populations in humid and semi-humid environments (* < 0.05; ** < 0.001; *** < 0.0001)