Before revision:  It is confirmed that T_s negatively correlates with the average of K_a/K_s. Stabilizing mutations are significantly fixed by positive selection, and balance with destabilizing mutations fixed by random drift.
After revision:  It is confirmed that T_s negatively correlates with the mean of K_a/K_s. Stabilizing mutations are significantly fixed by positive selection, and balance with destabilizing mutations fixed by random drift.