Degree of melanism in juvenile common frogs. Boxplot of the raw data from two populations ('North' = Björkliden, 68° 24' N; and 'South' = Tvedöra, 55° 42' N) reared in common garden. The degree of melanism is defined as the proportion of dorsal surface area covered by pigmentation spots large than 1 mm2. The boxes extend from 25th to 75th percentile, and the horizontal bands within the boxes are the medians. The whiskers represent the lowest and highest observation within 1.5 times the interquartile range from the lower and higher quartile, respectively. Labels 'High' and 'Low' describe temperature treatments.
Alho et al. BMC Evolutionary Biology 2010 10:317 doi:10.1186/1471-2148-10-317