Scientists have discovered that a female crocodile that lived alone in a wildlife park for more than 16 years laid more than a dozen eggs in 2018. This process of reproducing by herself is called parthenogenesis, or "virgin birth".
In a paper out Wednesday in the journal Biology Letters, a team of researchers report that the baby crocodile was a parthenogen - the product of a virgin birth, containing only genetic material from its mother. While parthenogenesis has been identified in creatures as diverse as king cobras, sawfish, and California condors, this is the first time it has been found in crocodiles. And because crocodiles fall on the tree of life, it implies that pterosaurs and dinosaurs might also have been capable of such reproductive feats, according to the New York Times.
This is the first instance of crocodile parthenogenesis that has been documented. Although the reason for certain animals' switch is unknown, it is believed to be "a response to when all else fails".
Seven of the 14 eggs laid by the crocodile in Costa Rica, according to the researchers' study, were viable.
These eggs were incubated by zookeepers, but since they didn't hatch, they were opened three months later.
While the contents of six of the eggs were "not discernable," one of them did contain a completely formed but non-viable foetus.
Genetic testing revealed that it was nearly identical to the mother.
The NYT report further explains how a virgin birth happens: As an egg cell matures in its mother's body, it divides repeatedly to generate a final product with exactly half the genes needed for an individual. Three smaller cellular sacs containing chromosomes, known as polar bodies, are formed as byproducts.
Polar bodies usually wither away. But in vertebrates that can perform parthenogenesis, one polar body sometimes fuses with the egg, creating a cell with the necessary complement of chromosomes to form an individual.
