Despite the near-magical nature of some epic level skill uses, all uses of skills are considered exceptional abilities (except if noted otherwise), and thus function normally even within areas of antimagic.
Skill Synergy
Many skills are noted as granting a synergy bonus to the use of another skill when a character has 5 or more ranks in the first skill. This synergy bonus increases by +2 for every additional 20 ranks the character has in the skill.