Actually the Burmese case of producing female offspring was noted as rare. I think more often it's been documented in snakes to produce only males.

Snakes are like birds and exactly opposite of mammals on gender determination. The female snake is zw and the male is zz. So it's the female that has the mixed chromosomes and determines the gender of the offspring with her contribution. Apparently most examples of parthenogenesis in snakes are like that leucistic water moccasin producing males. Not sure but thought I read that for that more common type half of the female's contribution gets doubled up to make a fully homozygous baby right down to the zz (the ww doubled ups don't survive as invalid). It could be that the mother water moccasin is heterozygous for a recessive white snake mutation and that male offspring also got two copies of that mutation doubled up. In the burm example somehow she made eggs that contained a clone of herself with both her halfs of every chromosome pair including the gender chromosomes so all female.

How rare this is we'll probably not know anytime soon because most everyone assumes it’s impossible or very rare and is not looking for it. It might even be no less rare in egg layers than livebearers it's just that most people assume the eggs with no apparent father are bad and throw them out. If by chance they do get properly incubated and hatch it would most likely be explained as retained sperm. Most everyone here is breeding so if you do happen to have a female you didn't pair this year you probably paired her sometime in the past and would expect that to be the source. The people this would likely happen to most would be lone pet owners who wouldn't have an incubator or experience on how to incubate. Without genetic testing there would only be unexpected morph situations that would have a chance to expose this (like if your male was a super pastel and you produced non pastel babies).

Doesn’t seem very likely that we’ll get down to a lone female Burmese in the Everglades anytime soon but I guess this could be an issue if that happens. Until then there is plenty of opportunity for regular reproduction in the one place in the US they can live.

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