No, the major microspecies is not a "subset" of the major tautomers. In fact, the reverse is true. I mean that when you calculate the major micros. for an input structure, you can select optionally to take into consideration the tautomerization. In this case the major micros. will be calculated for the major tautomer form. But this is not default behaviour.
However, you can take into account the pH effect when you calculate the major tautomer form for a molecule. It means that first you calculate the major tautomer form, and then take its major micro form at the given pH.
I hope this helps.