(A) Scatterplot showing for each yeast protein the evolutionary distance D to its orthologs in a higher eukaryote as a function of the proteins' number of interactions k. The thin black line corresponds to D ∼ αk with [TeX:] \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({\bar{{\alpha}}}=-0.0072\) \end{document} . (B) By applying logarithmic binning to the horizontal k-axis, we obtain improved correlations of the excess sequence conservation ESC_k on k (〈ESC_k〉 ∼ βlog k, [TeX:] \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({\bar{{\beta}}}=-0.152)\) \end{document} . (C) The orthologous excess retention parameter ER_k shown as a function of logarithmically binned ks indicates a statistically significant monotonic trend toward the conservation of the more connected proteins (ER_k ∼ γlog k, [TeX:] \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({\bar{{\gamma}}}=0.813)\) \end{document} ). In each plot, the symbols correspond to the orthologs of S. cerevisiae identified in the higher organisms listed in the legends box of C.