I thought you meant default as in "Regular vampire power" and etc. Well, we can only believe the Cyrodiilic vampires traveled to Skyrim. They can, I suppose, take over. As in lore, they took over Cyrodiil and ousted their competition, making Cyrodiil their strongold in the Third Era. Since it's the fourth, and the Empire crumbled, I see reason for them to leave to Skyrim. But in the game they are still depicted as fodder.
If that's the case, then Bethesda shouldn't have included mobs listed as Volkihar vampires.
What we have, here, is a half measure. We have two possibilities:
1.) There is only one vampire clan prevalent in Skyrim. If this is the Volkihar, they should NOT share the same traits as the vampires of Cyrodiil. If this is the Cyrodiilic clan, then they should not have any penalties to walking in the daylight during stage 1 vampirism.
2.) Both clans are in the game. If this is the case, then Bethesda should have implemented two forms of Vampirism, or at the very least, made it so that Volkihar vampires cannot infect you, as Volkihar vampires infecting you with the Cyrodiilic strain makes no sense
whatsoever.