In fact, GC and 5mC levels are positively correlated [50].Table 1: Mammalian species analyzed for GC % and DNA methylation.So, we can observe that, from one side, body temperature is a very strong factor influencing whole genomic methylation of vertebrates, and differences due to it are evident in ranges of 10???15 degrees (such as in the comparisons of tropical/polar fishes mammals/fishes).