On 22 June in a Wrocław terrarium a Komodo egg that had incubated for 202 days hatched a 34-centimetre lizard weighing 115 grams with no father at all, Poland's first, because the mother Flores produced him from an unfertilised egg and Komodo parthenogenesis makes only sons

On 22 June, in the Terrarium at Wrocław Zoo, a Komodo egg that had sat for 202 days split. What came out was about 34 centimetres long and weighed 115 grams. There was no male in the pairing. The mother is Flores. The zoo says this is the first Komodo dragon hatched in Poland, and the first in the garden’s history. Keepers later nicknamed him Florian, Florek for short. He is not on exhibit.

That is the whole job, stated as a count. Two hundred and two days. Thirty-four centimetres. One hundred and fifteen grams. No father. A son.

An egg with no father

Flores laid the eggs and buried them on the exhibit, which is what the species does. The city of Wrocław, working from the zoo’s account, says she then left them. There was no male on the scene and, the zoo says, none involved. The hatchling is genetically very similar to his mother. That is parthenogenesis: an unfertilised egg that still makes an animal.

The zoo did not show him on hatch day. It waited until 16 July, after he had begun to feed on his own, then said he would stay in the back of the Terrarium until he had grown and put on immunity. The body is not the dull armour of an adult. It is banded and spotted, high contrast, the camouflage wild hatchlings use when they go up trees. Adults eat young of their own species. The zoo puts that instinct on the record. This one does not need a tree yet. He needs quiet.

Why the hatchling is a son

Wrocław’s city write-up is blunt about the sex: this way of making a dragon produces exclusively males. That is not a zoo slogan. It is the chromosome arithmetic Phillip Watts and colleagues laid out in Nature in 2006, after two isolated females, Flora at Chester and Sungai at London Zoo, produced sons with no males present.

Komodo females are ZW. Males are ZZ. An unfertilised egg that doubles up one set of the mother’s chromosomes can make ZZ or WW. WW does not live. The survivors are sons. They are not clones. Nature’s news account of that paper says the sons carry half as much genetic variation as the mother, a doubled half, with no second animal in the mix. Wrocław has not published a fingerprinting study of this egg. It has published a hatch with no father, a weight, a length, and a species that, when it does this, makes males.

The 2006 paper also warned zoos that keeping females alone can trigger the trick and shrink the gene pool. Flores still did it. The egg still hatched. The son is 115 grams.

Still behind the glass

None of this is a viewing. The lizard is in the service rooms of the Terrarium. The zoo, with its DODO foundation, funds work at Wae Wuul on Flores, the island that shares the mother’s name. That is a separate ledger. What happened on 22 June is smaller. An egg incubated 202 days. A 34-centimetre animal came out at 115 grams. There was no father. Because this species’ unfertilised eggs only yield sons, Flores produced a male. He is still in the back. The first files of a Polish Komodo are a length, a mass, and an empty sire line.