Some feats have prerequisites. Your character must have the
indicated ability score, class feature, feat, skill, base attack bonus,
or other quality designated in order to select or use that feat. A
character can gain a feat at the same level at which he or she
gains the prerequisite. For example, at 3rd level, Krusk, the halforc
barbarian, could spend 1 skill point on the Ride skill
(gaining his first rank in Ride) and select the Mounted Combat
feat at the same time.
A character can’t use a feat if he or she has lost a prerequisite.
For example, if your character’s Strength drops below 13
because a ray of enfeeblement spell, he or she can’t use the Power
Attack feat until the prerequisite is once again met. A prerequisite
may not be met by use of temporary means, worn, held or spell.