A female crocodile living in isolation made herself pregnant in what is being hailed as the first known instance for the species.
In findings that stunned scientists, the offspring was found to be 99.9% genetically identical to its mother.
The research was led by biologist Warren Booth from Virginia Tech and recently published in the journal.
The 18-year-old crocodile had been living in a Costa Rica zoo since she was 2 years old and maintained separate from other crocodiles for the entirety of its life.
In 2018, the crocodile produced a clutch of 14 eggs, of which seven appeared to be fertile and were incubated. Six of those eggs were not discernible, but one had a fully-formed non-viable fetus, which scientists used to confirm its exact match to its mother.
Facultative parthenogenesis (FP) is the ability to generate offspring without male contribution, according to the study. While scientists have never before seen FP in crocodiles, it has been documented in birds, fish and reptiles — specifically lizards and snakes.
Researchers have noticed considerable growth in the phenomenon over the past two decades.