Fig. 1.

Estimates of coevolution. (A) Estimates of coevolution can rely on the number of species (gray squares) two proteins share. On top of that, across species that have both proteins (red-framed squares), one can search for a finer coevolution where the phylogenetic trees of gene pairs are compared either by the phylogeny comparison algorithm or by pair-wise correlation. (B) Our hypothesis was that GPCR−RAMP would show an intermediate degree of coevolution compared with random gene pairs and directly interacting gene pairs.