At a zoo in Costa Rica, the first instance of a crocodile getting pregnant on her own has been discovered.
She gave birth to a child that was 99.9% genetically identical to herself.
There have been instances of so-called “virgin birth” in some bird, fish, and reptile species, but never in crocodiles.
Scientists have discovered the first known occurrence of a crocodile laying eggs without a male mate, an unusual reproductive method that can be traced back to dinosaurs. Over the last two decades, zoologists have gathered further evidence of the extremely unusual vertebrate reproductive strategy of facultative parthenogenesis (FP), in which females lay eggs or give birth to their children without mating.
Until now, many creatures, including birds, non-avian reptiles such as lizards and snakes, and several fishes, including sharks, have been found to reproduce in this unusual method. However, issues have been raised about the existence of this reproduction mechanism outside of these vertebrate lineages, most notably among turtles, crocodiles, alligators, and gharials, according to scientists from Virginia Polytechnic Institute and State University in the United States.
Scientists have been particularly interested in looking for such a unique reproductive strategy in crocodilian species because these organisms lack sex chromosomes and their sex determination is governed by the temperature at which eggs grow and hatch.
“Virgin Birth” reveals the rare reproductive method
Scientists uncovered the first evidence of FP in the American crocodile, Crocodylus acutus, in a new study published on Wednesday in the journal Biology Letters. The most recent study is based on an observation in 2018 of a lone female American crocodile housed in custody for 16 years who deposited a clutch of eggs, one of which contained a detectable fetus, indicating she was a female like her mother.
According to the scientists, the discovery is the “first documentation” of this extremely rare way of reproduction in a crocodile species. Following DNA research, scientists determined that the mother crocodile laid the eggs without the assistance of a male mate, a phenomenon known as “virgin birth.”
While the eggs did not hatch, the discovery has piqued the interest of scientists because it suggests that the unique reproductive method is shared by reptiles, crocodilians, and birds. The findings suggest that extinct cousins of crocodilians and birds, such as dinosaurs and pterosaurs, may have used this unusual breeding technique as well.
“This new evidence offers tantalizing insights into the possible reproductive capabilities of extinct archosaurian relatives of crocodilians, notably the Pterosauria and Dinosauria,” scientists wrote in the study.