Figure 3: A phylogenetic tree showing the predicted abundance of disulfide bonding across the archaea. Each leaf of the tree is associated to specific values of the calculated disulfide abundance parameter ( 𝑓 ) and optimal growth temperature, which are depicted in respective circular plots, green (outer ring) and red (inner ring). These values are represented by the properties of the curves, which vary in thickness (and darkness) in proportion to the corresponding quantity. A general correlation is seen between disulfide richness and growth temperature; specifically, disulfide bonding is dominant in the Crenarchaea (blue) and also notable in the subset of thermophilic Euryarchaea that are nonmethanogenic.