The beneficiary under the joint and survivor annuity elected pursuant to paragraph (3) or (4) of subdivision (b) of Section 26807 or paragraphs (2) to (5), inclusive, of subdivision (a) of Section 26807.5 shall be the person designated by the participant on the application for a retirement benefit under this part, and shall not be changed after the original retirement date unless the beneficiary has predeceased the participant.