Quote Originally Posted by Mendel's Balls
Any idea of which species of monitor lizards have been claimed to show this phenomena?
Species that are commonly raised in groups....Varanus acanthurus sp. and other small monitors. Most people are 'so-so' on their opinions on the topic...some people believe it to be fact, others just a odd observation, and then people that think it is some bad information spread around.

For example, here is an excerpt for a caresheet by Pro-exotics when they touch on the subject
http://www.proexotics.com/care_ackie.html


For those of you wanting "a pair" of Ackies, or a "female" baby, you have to understand that monitors (of all types) are not visually sexable as babies, and there is absolutely no way to guarantee a particular sex when you are selling babies. Anyone who tells you different is trying to deceive you. Sexual characteristics start showing up as early as six months old, and as late as a year. You can look for head shapes, body shapes, hemipenal bulges, and other factors when trying to determine sex, but it is all still educated guess work. Unless a male monitor plainly everts a hemipene in your view, it is so very difficult to be sure of the sex of your animal (females will also evert a similar looking hemiclitoris, only confounding the situation). Some folks may have a "female" monitor for 3 years before it has suddenly everted a hemipene that wasn't thought to have existed in the first place.

However (and with dwarf monitors that’s a pretty BIG however), a pretty interesting and intriguing theory about the social sexing of hatchling dwarf monitors has emerged.

It is generally agreed (among the dwarf monitor breeders in the u.s.) that baby Ackies determine their gender according to social group after hatching. It is believed that one animal becomes a dominant male, and the other animals become female, basically. At this time, we have not had a customer report back to us with a male heavy group of Ackies purchased from Pro Exotics. Seeing as we group these animals immediately after hatching according to customer purchases and configurations, we have always had two Ackies be a pair, three Ackies be a trio (1.2), five Ackies be either 1.4 or 2.3, but not one instance of a heavy male group.
Some monitors are extreamly hard to sex (almost impossible) when they are young. So maybe, people have just assumed that they 'socially determine gender' because the 'gender indicators' are not present until almost adulthood.

I want to say that I have heard of research on the topic....but not to much of the findings.

Like I said, let me know if you come across anything