Crocodylus_acutus_mexico_02-edit1 By Tomás Castelazo - Own work, CC BY-SA 2.5
Crocodylus_acutus_mexico_02-edit1 By Tomás Castelazo - Own work, CC BY-SA 2.5

First 'virgin birth' seen in crocs

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Peer-reviewed: This work was reviewed and scrutinised by relevant independent experts.

US scientists looked at the DNA of an American crocodile mother, who lived an isolated life, and 12 of her eggs and found that a fully-formed fetus in one egg was genetically identical to its mum, suggesting it had developed without the egg being fertilised by a male croc. This type of reproduction, called facultative parthenogenesis, is known to occur in lots of other species including birds, lizards and snakes, but was not known in crocs before now. Although the eggs didn't hatch, the researchers say it's possible that now-extinct relatives of crocs, including dinosaurs, could reproduce in this way.

Journal/conference: Biology Letters

Research: Paper

Organisation/s: Virginia Polytechnic Institute and State University, USA

Funder: This work was supported by start-up funds provided by the College of Agriculture and Life Sciences at Virginia Polytechnic Institute and State University and the College of Engineering and Natural Sciences at The University of Tulsa to W.B.

Media release

From: The Royal Society

Discovery of Facultative Parthenogenesis in a New World Crocodile

Facultative parthenogenesis has been documented in multiple species of birds, lizards, snakes, and elasmobranch fishes. Nonetheless, questions remain as to its occurrence outside of these lineages; notably in Crocodylia (crocodiles, alligators, and gharials). Using whole-genome sequencing, we provide the first evidence of parthenogenesis in a crocodilian, the American Crocodile. The data support a parthenogenetic mechanism that shares a common evolutionary origin across reptiles, crocodilians, birds, and elasmobranchs. With parthenogenesis documented in the two main branches of extant archosaurs (crocodiles and birds), this discovery offers tantalizing insights into the possible reproductive capabilities of the extinct archosaurian, notably Dinosaurs and Pterosaurs.

Virgin crocs – The first ‘virgin birth’ in crocodiles could give insights into the reproductive capabilities of dinosaurs. One of twelve eggs, found in the enclosure of an isolated female American crocodile, contained a fully formed foetus which was genotypically identical to its mother. Although these eggs didn’t hatch, this case offers ‘tantalising insights’ into the reproductive capabilities of extinct archosaurs. 

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