Crocodile made herself pregnant at Costa Rica zoo, study says. Here’s how it’s possible
A female crocodile at a zoo in Costa Rica made herself pregnant and laid eggs, according to a recently published study by the Royal Society.
Though this is the first instance of this type of reproduction in a crocodile recorded by researchers, scientists say she’s probably not the only one with this ability, according to the study published June 7.
On Jan. 17, 2018, 14 eggs were discovered in the enclosure of an 18-year-old American crocodile at Parque Reptilandia in Costa Rica, according to the study published in the Royal Society’s Biology Letters.
The female had been at the zoo since she was 2 years old and had been isolated from other crocodiles ever since, according to the study.
Seven of the eggs appeared fertile and were brought to an incubator, the study says. After three months, they didn’t hatch, so scientists opened them to study their contents. One of the eggs contained a fully formed fetus that was determined to be female but non-viable.
The fetus’s genotype was 99.9% identical to its mother, the study says.
The ability to reproduce without the genetic contribution of males has been documented in other animals, such as some species of birds, snakes, lizards and fish, including sharks, rays and sawfish, the study says.
Crocodiles are different from those other species because crocodiles don’t have sex chromosomes, and determination of their sex is controlled by temperature, the study says. Eggs that are incubated at temperatures of about 86 degrees hatch female while eggs that reach temperatures of about 93 degrees hatch male, according to a separate study published by the Royal Society.
Dr. Warren Booth, a researcher at Virginia Tech and main author of the study, told BBC that because the ability to have “virgin births” is present in many different species, he believes it may be an “ancient trait” inherited through evolution. Booth told the outlet dinosaurs may have reproduced this way as their numbers started to decline and they were threatened with extinction.
Booth did not immediately respond to a request for comment from McClatchy News.
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