 It has been argued that effect macroevolution is reducible to microevolution because both operate through selection on organismic traits, but Grantham demonstrated that effect macroevolution can oppose selection at the organismic level and is therefore not reducible microevolution.Cases in which selection on the same trait has opposing effects at the organismic and the species level have been made in the context of sexual selection, which increases individual fitness but may also increase the extinction risk of the species.Punctuated equilibrium postulates that evolutionary change is concentrated during a geologically short speciation phase, which is followed by evolutionary stasis that persists until the species goes extinct.