The most simple case would be when alpha is zero. This means that there is no quadrupole correction to the energy level and we just see a flatline.
The other case is where alpha is larger than zero. Here we have a contribution to the monopole term which is a split from alpha above the monopole level to 2alpha below that level, as seen in the lecture.
The last case is where the alpha is lower than zero. This would just mean an inversion to the positive alpha case, i.e. 2alpha above the uncorrected monopole level and alpha below the uncorrected monopole level.