Resolution:
## Figure 3.
The effects of latitude and body length on the degree of melanism. The figure shows the relationship between a) latitude and the degree of melanism
and b) snout-vent length and the degree of melanism in adult common frogs caught from
the wild. The degree of melanism is defined as the proportion of dorsal surface area
covered by pigmentation spots large than 1 mm^{2}. In figure (a) the circles represent means and vertical bars standard errors of the
means. In figure (b) the circles represent partial residuals after correcting for
population effects and latitude (fixed at the mean of the data, 61°16'N). The curves
in both figures describe the predicted degree of melanism. The prediction curves and
partial residuals are based on a linear mixed model incorporating sex, latitude, snout-vent
length, the interaction of sex and latitude, and the interaction of sex and snout-vent
length as fixed effects, and population as a random effect. The model was fitted to
arcsine transformed data. The curves are back-transformed predictions and hence not
linear.
Alho |