Fig. 2

Desaturation index of blubber fatty acids as a function of latitude for pinnipeds, separated by blubber section used for analyses: whole blubber core (from skin to muscle; n = 6) or only the outer layer (section just beneath the skin; n = 14). Based on phylogenetic generalised least squares (PGLS), the dashed regression line indicates a non-significant correlation for whole blubber fatty acids (y = 0.03(x) + 1.01) whereas the solid line indicates significant correlation for outer blubber fatty acids (y = 0.07(x) − 0.41)