The investigator talent Alchemist Discovery says
The investigator can select one of the following alchemist discoveries as an investigator talent: combine extracts, concentrate poison, dilution, elixir of life, enhance potion, eternal potion, extend potion, infusion, mutagen, and poison conversion. When selecting an alchemist discovery, he must be high enough level to qualify for that discovery, using his investigator level as his alchemist level to determine if he qualifies. This talent can be selected multiple times; each time grants a new alchemist discovery.
Based on this wording, I wonder if the only prerequisite for alchemist discoveries through this method is the level requirement. For example, if I wanted to pick up the Eternal Potion alchemist discovery from investigator talents, can I avoid the extend potion prerequisite?
That's there because without it the Investigator doesn't qualify for the discovery. It's allowing you to bypass one prerequisite of the discovery (alchemist levels) by replacing it with another (Investigator levels).
So any other prerequisites are still applicable.