Alter Self and Extraordinary Special Qualities

Suppose you are a dwarf and use Alter Self to become a different dwarf. Do you lose your darkvision?

The text of Alter Self states:

You keep all extraordinary special attacks and qualities derived from class levels, but you lose any from your normal form that are not derived from class levels.

Since darkvision is an extraordinary special quality not derived from class levels, it appears you would lose that ability, but this seems very counterintuitive. Would the same be true for Polymorph? Does it require a ninth level spell for you to keep your darkvision when trying to become a different dwarf?