To help mitigate inbreeding depression for two endangered species, the Black-footed ferret(Mustela nigripes), Revive & Restore facilitates on-going efforts to clone individuals from historic cell lines stored at the San Diego Zoo Wildlife Alliance Frozen Zoo. The program seeks to restore genetic variation lost from the living gene pool.
On December 10, 2020, the world's first cloned black-footed ferret was born. This ferret, named Elizabeth Ann, marked the first time a U.S. endangered species was successfully cloned. 
The cells of two 1980s wild-caught black-footed ferrets that never bred in captivity were preserved in the San Diego Wildlife Alliance Frozen Zoo. One of them was cloned to increase genetic diversity in this species in December 2020. More clones of both are planned. They will initially be bred separately from the non-cloned population.