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 #830761


Krusty
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 Ackies and sex determination phenom.

Have there been any studies launched to determine if, in fact, groups of young ackies do become male and female due to their social interactions? It has been suggested for many years that they do this, but nothing scientific to my knowledge...all heresay. I keep reading this repeatedly from keepers/breeders over the years. I have never stumbled upon a scientific type study.
06/12/06  09:45pm

 #831107


Crocdoc
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   Message To: Krusty   In reference to Message Id: 830761


 Ackies and sex determination phenom.

My guess is that it is entirely a probability thing, so that it ’seems’ like you always get a male and a female (you don’t). Link

You’re not likely to see any scientific study on it for a number of reasons. One of the most basic reasons is that it’s based on an odd premise: That wild hatchling monitors hang around with each other and grow up to be pairs that inbreed and whose inbred offspring then grow up together and further the inbreeding process. The reason this premise came about is because it is known to be easier to have monitors get along in captivity if you raise them together, just as raising kittens and puppies together helps them get along as adults (yet no one suggests that dogs and cats are chummy in the wild).

The problem with captivity is that if monitors don’t get along, there’s nowhere for them to go so they end up damaging each other, something that occurs far more rarely in the wild. In other words, you don’t need pairs to grow up together to get along in the wild, because they’re never forced together - they get together only when they want or need to (ie a male is not going to go through the trouble of searching out a receptive female only to beat up on her, whereas in captivity people throw males and females into enclosures of limited size and hope they get along).

A lot of the odd ’theories’ about monitors that come out of the pet trade are based on what captives do or don’t do, unfortunately, and then attempts are made to extrapolate those behaviours onto wild monitors.



06/13/06  02:20am

 #832370


Krusty
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   Message To: Crocdoc   In reference to Message Id: 831107


 Ackies and sex determination phenom.

Yeah, i understand the basic 50:50 odds with sex chromosomes. But there are examples of lizards that can reproduce parthenogenetically (whiptails) in all female populations, environmental polutants that can convert amphibian populations to all females, TDSD egg development, fish that convert to females with size/age, etc....there are exceptions to the "normal". In all likelihood it is just the odds that of 3 monitors, one or two is likely to be female vs male...and the 50:50 stats are more accurate with a larger sample size. It would be interesting to see with a female ackie producing 50 or so eggs per year, a study that groups them out into 4’s and then watches them to adulthood vs. individually raised. There could be some hormonal basis, possibly, that the dominant animal biologically becomes male and the submissive becomes female. Are their genitals formed at birth such that a necropsy could tell male vs female? Just throwing the rare possibility out there for someone who breeds them to take on a project. P.S. dont slaughter your young for necropsies.
06/13/06  10:22pm

 #832496


Crocdoc
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   Message To: Krusty   In reference to Message Id: 832370


 Ackies and sex determination phenom.

Thanks, I’m well aware of parthenogenesis, temperature dependant sex, sex changes in fishes etc. However, these are all entirely different phenomena than what we are talking about. They also make sense for the biology of the animals in question - except for the anomalies of all female species with parthenogenesis, which in the long run will be a minor glitch on the radar screen of evolution, and man-made pollutant affected amphibians.

For starters, monitors have differentiated sex chromosomes.
Secondly, the biology of their wild counterparts: If it were a dominance/submissive hormonally induced situation (unlikely with differentiated sex chromosomes), why would monitors need to be raised together for it to express itself when they don’t hang around in groups as babies (getting back to our wild siblings growing up male and female just to inbreed being a quick road to extinction).

Before someone spends a lot of time and money researching it, perhaps spend a weekend trying to think of a reasonable scenario in which this sort of gender assignment would make biological sense, considering the natural history of monitors. Once you’ve conquered that, then you’d have a good reason to carry out the research.

By the way, four hatchlings from my first clutch turned out 3:1. Wouldn’t be much good as a sex ratio.
06/13/06  11:57pm

 #832629


Treemonitors
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   Message To: Crocdoc   In reference to Message Id: 832496


 Ackies and sex determination phenom.

If you talk to Joe Lewis, founder of Rare Earth, he will tell you all about the 9 or 10 Varanus pilbarensis hatchlings he purchased from a certain southeastern US breeder, shortly after captive bred individuals of this species first became available to the public (and I’m sure he paid quite a fortune for them back then!). In those 9 or 10 individuals, he ended up with a single female. Fortunate enough, Joe was able to found his entire line of V. pilbarensis (Rare Earth is the largest producer of this species in the country) with this single female.

So much for the "social pairs" theory...



06/14/06  02:21am


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