Believe it or not, a crocodile made herself pregnant. A rare case of ‘virgin birth’

A crocodile in Costa Rica has made herself pregnant, which is said to be the first recorded instance of a "virgin birth" in the reptile species as scientists have found evidence that female crocodiles can lay eggs without mating. Virgin birth is known as facultative parthenogenesis and it has been documented in fish, lizards and snakes, but this is the first case in crocodiles.

The study mentioned that the mentioned crocodile was kept in captivity in a zoo and had no contact with males. In fact, the crocodile had no contact with males for about 16 years. However, a fully-formed foetus was discovered inside one of her eggs. The foetus was 99.9 per cent genetically identical to the mother.

The study published in Biology Letters — titled "Discovery of facultative parthenogenesis in a new world crocodile" — said that the female crocodile used a strange reproductive strategy, a method which may have its evolutionary roots in the age of the dinosaurs.

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"[T]his discovery offers tantalizing insights into the possible reproductive capabilities of the extinct archosaurian relatives of crocodilians and birds, notably members of Pterosauria and Dinosauria," writes the team of researchers led by evolutionary biologist Warren Booth from Virginia Tech.

Part of the study read the ability of sexually reproducing species to generate offspring without the genetic contributions of males was once considered rare.

But it has been documented across multiple vertebrate lineages, including both avian and non-avian reptiles, and elasmobranch fishes, with notable examples in sharks, rays and sawfish.

The researchers from Virginia Tech have analysed the foetus. The researchers specialise in parthenogenesis and they published their findings in the Royal Society journal Biology Letters.

As quoted by Sky News, they said that the discovery suggests virgin births could be happening in crocodiles without anyone realising it.

"It is not uncommon for captive reptiles to lay clutches of eggs, given the period of isolation from mates, these would normally be considered non-viable and discarded. These findings, therefore, suggest that eggs should be assessed for potential viability when males are absent," they said.

"Furthermore, given that (virgin births) can occur in the presence of potential mates, instances of this may be missed when reproduction occurs in females co-habited with males," they added.

The study found that "genome-wide maternal heterozygosity was 0.349, compared to 0.045 for the offspring, demonstrating a significant reduction in heterozygosity in the offspring when compared to the mother".

"Regardless of the dataset evaluated, the offspring retained approximately 3% of the maternal heterozygosity (table 1), supporting FP through terminal fusion automixis as the mode of reproduction," it added.

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