Table 1:

Ancestral reconstruction studies of specific molecular interactions. For each protein family studied, the cladogram shows the specific biological or biochemical property assayed, its distribution among extant and reconstructed ancestral proteins (circles). Protein families are grouped on the basis of their evolutionary history: de novo evolution of a new specific function after gene duplication (purple), partitioning of functions from a multifunctional ancestor (green), or partitioning of functions from a multifunctional ancestor with refinement of an ancestral activity in one or both lineages (orange). For studies that dissect genetic mechanisms, the number of large-effect replacements necessary to recapitulate the shift in specificity is shown on the lineage on which they occurred. Red letters, major function or activity (high affinity, catalytic efficiency, etc.); gray, minor function (lower affinity, etc.).