Crocodile found to have made herself pregnant leaving scientists stunned

A crocodile has made herself pregnant in the first observed case of its kind involving the reptile.

The croc produced a foetus that was 99.9% genetically identical to herself at a zoo in Costa Rica – confirming it had no father.

The so-called “virgin birth” phenomenon has been found in species other reptiles, as well as in fish and birds, but never before in crocodiles.

The egg was laid by an 18-year-old female American crocodile in Parque Reptilania in January 2018, the BBC reports. The foetus inside was fully formed but still born and so did not hatch.

Researchers from Virginia Polytechnic, which specialised in virgin births (or parthenogenesis), say such cases may be more common in crocodiles but they could simply have gone unnoticed.

Writing in the Royal Society journal Biology Letters, the researchers said: “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.

“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”.

The reason which why parthenogenesis occurs in different species is something of a mystery.

One contending theory is that it happens when numbers of a particular species dwindle, and they are on the verge of extinction.

This article by Michael Howie was first published by The Evening Standard on 8 June 2023. Lead Image: PA Media.

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